GenericObjectPool (Apache Tomcat 7.0.109 API Documentation)

java.lang.Object
- org.apache.tomcat.dbcp.pool.BaseObjectPool<T>
- - org.apache.tomcat.dbcp.pool.impl.GenericObjectPool<T>

Type Parameters:
T - the type of objects held in this pool

All Implemented Interfaces:

ObjectPool<T>

Direct Known Subclasses:

AbandonedObjectPool
```
public class GenericObjectPool<T>
extends BaseObjectPool<T>
```
A configurable ObjectPool implementation.
When coupled with the appropriate PoolableObjectFactory, GenericObjectPool provides robust pooling functionality for arbitrary objects.
A GenericObjectPool provides a number of configurable parameters:
- maxActive controls the maximum number of objects that can be allocated by the pool (checked out to clients, or idle awaiting checkout) at a given time. When non-positive, there is no limit to the number of objects that can be managed by the pool at one time. When maxActive is reached, the pool is said to be exhausted. The default setting for this parameter is 8.
- maxIdle controls the maximum number of objects that can sit idle in the pool at any time. When negative, there is no limit to the number of objects that may be idle at one time. The default setting for this parameter is 8.
- whenExhaustedAction specifies the behavior of the borrowObject() method when the pool is exhausted:
  - When whenExhaustedAction is WHEN_EXHAUSTED_FAIL, borrowObject() will throw a NoSuchElementException
  - When whenExhaustedAction is WHEN_EXHAUSTED_GROW, borrowObject() will create a new object and return it (essentially making maxActive meaningless.)
  - When whenExhaustedAction is WHEN_EXHAUSTED_BLOCK, borrowObject() will block (invoke Object.wait()) until a new or idle object is available. If a positive maxWait value is supplied, then borrowObject() will block for at most that many milliseconds, after which a NoSuchElementException will be thrown. If maxWait is non-positive, the borrowObject() method will block indefinitely.
  The default whenExhaustedAction setting is WHEN_EXHAUSTED_BLOCK and the default maxWait setting is -1. By default, therefore, borrowObject will block indefinitely until an idle instance becomes available.
- When testOnBorrow is set, the pool will attempt to validate each object before it is returned from the borrowObject() method. (Using the provided factory's PoolableObjectFactory.validateObject(T) method.) Objects that fail to validate will be dropped from the pool, and a different object will be borrowed. The default setting for this parameter is false.
- When testOnReturn is set, the pool will attempt to validate each object before it is returned to the pool in the returnObject(T) method. (Using the provided factory's PoolableObjectFactory.validateObject(T) method.) Objects that fail to validate will be dropped from the pool. The default setting for this parameter is false.
Optionally, one may configure the pool to examine and possibly evict objects as they sit idle in the pool and to ensure that a minimum number of idle objects are available. This is performed by an "idle object eviction" thread, which runs asynchronously. Caution should be used when configuring this optional feature. Eviction runs contend with client threads for access to objects in the pool, so if they run too frequently performance issues may result. The idle object eviction thread may be configured using the following attributes:
- timeBetweenEvictionRunsMillis indicates how long the eviction thread should sleep before "runs" of examining idle objects. When non-positive, no eviction thread will be launched. The default setting for this parameter is -1 (i.e., idle object eviction is disabled by default).
- minEvictableIdleTimeMillis specifies the minimum amount of time that an object may sit idle in the pool before it is eligible for eviction due to idle time. When non-positive, no object will be dropped from the pool due to idle time alone. This setting has no effect unless timeBetweenEvictionRunsMillis > 0. The default setting for this parameter is 30 minutes.
- testWhileIdle indicates whether or not idle objects should be validated using the factory's PoolableObjectFactory.validateObject(T) method. Objects that fail to validate will be dropped from the pool. This setting has no effect unless timeBetweenEvictionRunsMillis > 0. The default setting for this parameter is false.
- softMinEvictableIdleTimeMillis specifies the minimum amount of time an object may sit idle in the pool before it is eligible for eviction by the idle object evictor (if any), with the extra condition that at least "minIdle" object instances remain in the pool. When non-positive, no objects will be evicted from the pool due to idle time alone. This setting has no effect unless timeBetweenEvictionRunsMillis > 0. and it is superceded by minEvictableIdleTimeMillis (that is, if minEvictableIdleTimeMillis is positive, then softMinEvictableIdleTimeMillis is ignored). The default setting for this parameter is -1 (disabled).
- numTestsPerEvictionRun determines the number of objects examined in each run of the idle object evictor. This setting has no effect unless timeBetweenEvictionRunsMillis > 0. The default setting for this parameter is 3.
The pool can be configured to behave as a LIFO queue with respect to idle objects - always returning the most recently used object from the pool, or as a FIFO queue, where borrowObject always returns the oldest object in the idle object pool.
- lifo determines whether or not the pool returns idle objects in last-in-first-out order. The default setting for this parameter is true.
GenericObjectPool is not usable without a PoolableObjectFactory. A non-null factory must be provided either as a constructor argument or via a call to setFactory(org.apache.tomcat.dbcp.pool.PoolableObjectFactory<T>) before the pool is used.
Implementation note: To prevent possible deadlocks, care has been taken to ensure that no call to a factory method will occur within a synchronization block. See POOL-125 and DBCP-44 for more information.
Since:

Pool 1.0

Author:

Rodney Waldhoff, Dirk Verbeeck, Sandy McArthur

See Also:
GenericKeyedObjectPool

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static class GenericObjectPool.Config
A simple "struct" encapsulating the configuration information for a GenericObjectPool.

Nested Classes
Modifier and Type	Class and Description
`static class`	`GenericObjectPool.Config` A simple "struct" encapsulating the configuration information for a `GenericObjectPool`.

Field Summary

Fields
Modifier and Type	Field and Description
`static boolean`	`DEFAULT_LIFO` The default LIFO status.
`static int`	`DEFAULT_MAX_ACTIVE` The default cap on the total number of active instances from the pool.
`static int`	`DEFAULT_MAX_IDLE` The default cap on the number of "sleeping" instances in the pool.
`static long`	`DEFAULT_MAX_WAIT` The default maximum amount of time (in milliseconds) the `borrowObject()` method should block before throwing an exception when the pool is exhausted and the `"when exhausted" action` is `WHEN_EXHAUSTED_BLOCK`.
`static long`	`DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS` The default value for `getMinEvictableIdleTimeMillis()`.
`static int`	`DEFAULT_MIN_IDLE` The default minimum number of "sleeping" instances in the pool before before the evictor thread (if active) spawns new objects.
`static int`	`DEFAULT_NUM_TESTS_PER_EVICTION_RUN` The default number of objects to examine per run in the idle object evictor.
`static long`	`DEFAULT_SOFT_MIN_EVICTABLE_IDLE_TIME_MILLIS` The default value for `getSoftMinEvictableIdleTimeMillis()`.
`static boolean`	`DEFAULT_TEST_ON_BORROW` The default "test on borrow" value.
`static boolean`	`DEFAULT_TEST_ON_RETURN` The default "test on return" value.
`static boolean`	`DEFAULT_TEST_WHILE_IDLE` The default "test while idle" value.
`static long`	`DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS` The default "time between eviction runs" value.
`static byte`	`DEFAULT_WHEN_EXHAUSTED_ACTION` The default "when exhausted action" for the pool.
`static byte`	`WHEN_EXHAUSTED_BLOCK` A "when exhausted action" type indicating that when the pool is exhausted (i.e., the maximum number of active objects has been reached), the `borrowObject()` method should block until a new object is available, or the `maximum wait time` has been reached.
`static byte`	`WHEN_EXHAUSTED_FAIL` A "when exhausted action" type indicating that when the pool is exhausted (i.e., the maximum number of active objects has been reached), the `borrowObject()` method should fail, throwing a `NoSuchElementException`.
`static byte`	`WHEN_EXHAUSTED_GROW` A "when exhausted action" type indicating that when the pool is exhausted (i.e., the maximum number of active objects has been reached), the `borrowObject()` method should simply create a new object anyway.

Constructor Summary

Constructors
Constructor and Description
`GenericObjectPool()` Create a new `GenericObjectPool` with default properties.
`GenericObjectPool(PoolableObjectFactory<T> factory)` Create a new `GenericObjectPool` using the specified factory.
`GenericObjectPool(PoolableObjectFactory<T> factory, GenericObjectPool.Config config)` Create a new `GenericObjectPool` using the specified values.
`GenericObjectPool(PoolableObjectFactory<T> factory, int maxActive)` Create a new `GenericObjectPool` using the specified values.
`GenericObjectPool(PoolableObjectFactory<T> factory, int maxActive, byte whenExhaustedAction, long maxWait)` Create a new `GenericObjectPool` using the specified values.
`GenericObjectPool(PoolableObjectFactory<T> factory, int maxActive, byte whenExhaustedAction, long maxWait, boolean testOnBorrow, boolean testOnReturn)` Create a new `GenericObjectPool` using the specified values.
`GenericObjectPool(PoolableObjectFactory<T> factory, int maxActive, byte whenExhaustedAction, long maxWait, int maxIdle)` Create a new `GenericObjectPool` using the specified values.
`GenericObjectPool(PoolableObjectFactory<T> factory, int maxActive, byte whenExhaustedAction, long maxWait, int maxIdle, boolean testOnBorrow, boolean testOnReturn)` Create a new `GenericObjectPool` using the specified values.
`GenericObjectPool(PoolableObjectFactory<T> factory, int maxActive, byte whenExhaustedAction, long maxWait, int maxIdle, boolean testOnBorrow, boolean testOnReturn, long timeBetweenEvictionRunsMillis, int numTestsPerEvictionRun, long minEvictableIdleTimeMillis, boolean testWhileIdle)` Create a new `GenericObjectPool` using the specified values.
`GenericObjectPool(PoolableObjectFactory<T> factory, int maxActive, byte whenExhaustedAction, long maxWait, int maxIdle, int minIdle, boolean testOnBorrow, boolean testOnReturn, long timeBetweenEvictionRunsMillis, int numTestsPerEvictionRun, long minEvictableIdleTimeMillis, boolean testWhileIdle)` Create a new `GenericObjectPool` using the specified values.
`GenericObjectPool(PoolableObjectFactory<T> factory, int maxActive, byte whenExhaustedAction, long maxWait, int maxIdle, int minIdle, boolean testOnBorrow, boolean testOnReturn, long timeBetweenEvictionRunsMillis, int numTestsPerEvictionRun, long minEvictableIdleTimeMillis, boolean testWhileIdle, long softMinEvictableIdleTimeMillis)` Create a new `GenericObjectPool` using the specified values.
`GenericObjectPool(PoolableObjectFactory<T> factory, int maxActive, byte whenExhaustedAction, long maxWait, int maxIdle, int minIdle, boolean testOnBorrow, boolean testOnReturn, long timeBetweenEvictionRunsMillis, int numTestsPerEvictionRun, long minEvictableIdleTimeMillis, boolean testWhileIdle, long softMinEvictableIdleTimeMillis, boolean lifo)` Create a new `GenericObjectPool` using the specified values.

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`addObject()` Create an object, and place it into the pool.
`T`	`borrowObject()` Borrows an object from the pool.
`void`	`clear()` Clears any objects sitting idle in the pool by removing them from the idle instance pool and then invoking the configured `PoolableObjectFactory.destroyObject(Object)` method on each idle instance.
`void`	`close()` Closes the pool.
`void`	`evict()` Perform `numTests` idle object eviction tests, evicting examined objects that meet the criteria for eviction.
`boolean`	`getLifo()` Whether or not the idle object pool acts as a LIFO queue.
`int`	`getMaxActive()` Returns the maximum number of objects that can be allocated by the pool (checked out to clients, or idle awaiting checkout) at a given time.
`int`	`getMaxIdle()` Returns the cap on the number of "idle" instances in the pool.
`long`	`getMaxWait()` Returns the maximum amount of time (in milliseconds) the `borrowObject()` method should block before throwing an exception when the pool is exhausted and the `"when exhausted" action` is `WHEN_EXHAUSTED_BLOCK`.
`long`	`getMinEvictableIdleTimeMillis()` Returns the minimum amount of time an object may sit idle in the pool before it is eligible for eviction by the idle object evictor (if any).
`int`	`getMinIdle()` Returns the minimum number of objects allowed in the pool before the evictor thread (if active) spawns new objects.
`int`	`getNumActive()` Return the number of instances currently borrowed from this pool.
`int`	`getNumIdle()` Return the number of instances currently idle in this pool.
`int`	`getNumTestsPerEvictionRun()` Returns the max number of objects to examine during each run of the idle object evictor thread (if any).
`long`	`getSoftMinEvictableIdleTimeMillis()` Returns the minimum amount of time an object may sit idle in the pool before it is eligible for eviction by the idle object evictor (if any), with the extra condition that at least "minIdle" amount of object remain in the pool.
`boolean`	`getTestOnBorrow()` When `true`, objects will be `validated` before being returned by the `borrowObject()` method.
`boolean`	`getTestOnReturn()` When `true`, objects will be `validated` before being returned to the pool within the `returnObject(T)`.
`boolean`	`getTestWhileIdle()` When `true`, objects will be `validated` by the idle object evictor (if any).
`long`	`getTimeBetweenEvictionRunsMillis()` Returns the number of milliseconds to sleep between runs of the idle object evictor thread.
`byte`	`getWhenExhaustedAction()` Returns the action to take when the `borrowObject()` method is invoked when the pool is exhausted (the maximum number of "active" objects has been reached).
`void`	`invalidateObject(T obj)` Invalidates an object from the pool.
`void`	`returnObject(T obj)` Returns an object instance to the pool.
`void`	`setConfig(GenericObjectPool.Config conf)` Sets my configuration.
`void`	`setFactory(PoolableObjectFactory<T> factory)` Deprecated. to be removed in version 2.0
`void`	`setLifo(boolean lifo)` Sets the LIFO property of the pool.
`void`	`setMaxActive(int maxActive)` Sets the cap on the number of objects that can be allocated by the pool (checked out to clients, or idle awaiting checkout) at a given time.
`void`	`setMaxIdle(int maxIdle)` Sets the cap on the number of "idle" instances in the pool.
`void`	`setMaxWait(long maxWait)` Sets the maximum amount of time (in milliseconds) the `borrowObject()` method should block before throwing an exception when the pool is exhausted and the `"when exhausted" action` is `WHEN_EXHAUSTED_BLOCK`.
`void`	`setMinEvictableIdleTimeMillis(long minEvictableIdleTimeMillis)` Sets the minimum amount of time an object may sit idle in the pool before it is eligible for eviction by the idle object evictor (if any).
`void`	`setMinIdle(int minIdle)` Sets the minimum number of objects allowed in the pool before the evictor thread (if active) spawns new objects.
`void`	`setNumTestsPerEvictionRun(int numTestsPerEvictionRun)` Sets the max number of objects to examine during each run of the idle object evictor thread (if any).
`void`	`setSoftMinEvictableIdleTimeMillis(long softMinEvictableIdleTimeMillis)` Sets the minimum amount of time an object may sit idle in the pool before it is eligible for eviction by the idle object evictor (if any), with the extra condition that at least "minIdle" object instances remain in the pool.
`void`	`setTestOnBorrow(boolean testOnBorrow)` When `true`, objects will be `validated` before being returned by the `borrowObject()` method.
`void`	`setTestOnReturn(boolean testOnReturn)` When `true`, objects will be `validated` before being returned to the pool within the `returnObject(T)`.
`void`	`setTestWhileIdle(boolean testWhileIdle)` When `true`, objects will be `validated` by the idle object evictor (if any).
`void`	`setTimeBetweenEvictionRunsMillis(long timeBetweenEvictionRunsMillis)` Sets the number of milliseconds to sleep between runs of the idle object evictor thread.
`void`	`setWhenExhaustedAction(byte whenExhaustedAction)` Sets the action to take when the `borrowObject()` method is invoked when the pool is exhausted (the maximum number of "active" objects has been reached).
`protected void`	`startEvictor(long delay)` Start the eviction thread or service, or when delay is non-positive, stop it if it is already running.

Methods inherited from class org.apache.tomcat.dbcp.pool.BaseObjectPool
assertOpen, isClosed

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - WHEN_EXHAUSTED_FAIL
```
public static final byte WHEN_EXHAUSTED_FAIL
```
    A "when exhausted action" type indicating that when the pool is exhausted (i.e., the maximum number of active objects has been reached), the borrowObject() method should fail, throwing a NoSuchElementException.
    
    See Also:
    WHEN_EXHAUSTED_BLOCK, WHEN_EXHAUSTED_GROW, setWhenExhaustedAction(byte), Constant Field Values
  - WHEN_EXHAUSTED_BLOCK
```
public static final byte WHEN_EXHAUSTED_BLOCK
```
    A "when exhausted action" type indicating that when the pool is exhausted (i.e., the maximum number of active objects has been reached), the borrowObject() method should block until a new object is available, or the maximum wait time has been reached.
    
    See Also:
    WHEN_EXHAUSTED_FAIL, WHEN_EXHAUSTED_GROW, setMaxWait(long), getMaxWait(), setWhenExhaustedAction(byte), Constant Field Values
  - WHEN_EXHAUSTED_GROW
```
public static final byte WHEN_EXHAUSTED_GROW
```
    A "when exhausted action" type indicating that when the pool is exhausted (i.e., the maximum number of active objects has been reached), the borrowObject() method should simply create a new object anyway.
    
    See Also:
    WHEN_EXHAUSTED_FAIL, WHEN_EXHAUSTED_GROW, setWhenExhaustedAction(byte), Constant Field Values
  - DEFAULT_MAX_IDLE
```
public static final int DEFAULT_MAX_IDLE
```
    The default cap on the number of "sleeping" instances in the pool.
    
    See Also:
    getMaxIdle(), setMaxIdle(int), Constant Field Values
  - DEFAULT_MIN_IDLE
```
public static final int DEFAULT_MIN_IDLE
```
    The default minimum number of "sleeping" instances in the pool before before the evictor thread (if active) spawns new objects.
    
    See Also:
    getMinIdle(), setMinIdle(int), Constant Field Values
  - DEFAULT_MAX_ACTIVE
```
public static final int DEFAULT_MAX_ACTIVE
```
    The default cap on the total number of active instances from the pool.
    
    See Also:
    getMaxActive(), Constant Field Values
  - DEFAULT_WHEN_EXHAUSTED_ACTION
```
public static final byte DEFAULT_WHEN_EXHAUSTED_ACTION
```
    The default "when exhausted action" for the pool.
    
    See Also:
    WHEN_EXHAUSTED_BLOCK, WHEN_EXHAUSTED_FAIL, WHEN_EXHAUSTED_GROW, setWhenExhaustedAction(byte), Constant Field Values
  - DEFAULT_LIFO
```
public static final boolean DEFAULT_LIFO
```
    The default LIFO status. True means that borrowObject returns the most recently used ("last in") idle object in the pool (if there are idle instances available). False means that the pool behaves as a FIFO queue - objects are taken from the idle object pool in the order that they are returned to the pool.
    
    Since:
    
    1.4
    
    See Also:
    setLifo(boolean), Constant Field Values
  - DEFAULT_MAX_WAIT
```
public static final long DEFAULT_MAX_WAIT
```
    The default maximum amount of time (in milliseconds) the borrowObject() method should block before throwing an exception when the pool is exhausted and the "when exhausted" action is WHEN_EXHAUSTED_BLOCK.
    
    See Also:
    getMaxWait(), setMaxWait(long), Constant Field Values
  - DEFAULT_TEST_ON_BORROW
```
public static final boolean DEFAULT_TEST_ON_BORROW
```
    The default "test on borrow" value.
    
    See Also:
    getTestOnBorrow(), setTestOnBorrow(boolean), Constant Field Values
  - DEFAULT_TEST_ON_RETURN
```
public static final boolean DEFAULT_TEST_ON_RETURN
```
    The default "test on return" value.
    
    See Also:
    getTestOnReturn(), setTestOnReturn(boolean), Constant Field Values
  - DEFAULT_TEST_WHILE_IDLE
```
public static final boolean DEFAULT_TEST_WHILE_IDLE
```
    The default "test while idle" value.
    
    See Also:
    getTestWhileIdle(), setTestWhileIdle(boolean), getTimeBetweenEvictionRunsMillis(), setTimeBetweenEvictionRunsMillis(long), Constant Field Values
  - DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS
```
public static final long DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS
```
    The default "time between eviction runs" value.
    
    See Also:
    getTimeBetweenEvictionRunsMillis(), setTimeBetweenEvictionRunsMillis(long), Constant Field Values
  - DEFAULT_NUM_TESTS_PER_EVICTION_RUN
```
public static final int DEFAULT_NUM_TESTS_PER_EVICTION_RUN
```
    The default number of objects to examine per run in the idle object evictor.
    
    See Also:
    getNumTestsPerEvictionRun(), setNumTestsPerEvictionRun(int), getTimeBetweenEvictionRunsMillis(), setTimeBetweenEvictionRunsMillis(long), Constant Field Values
  - DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS
```
public static final long DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS
```
    The default value for getMinEvictableIdleTimeMillis().
    
    See Also:
    getMinEvictableIdleTimeMillis(), setMinEvictableIdleTimeMillis(long), Constant Field Values
  - DEFAULT_SOFT_MIN_EVICTABLE_IDLE_TIME_MILLIS
```
public static final long DEFAULT_SOFT_MIN_EVICTABLE_IDLE_TIME_MILLIS
```
    The default value for getSoftMinEvictableIdleTimeMillis().
    
    See Also:
    getSoftMinEvictableIdleTimeMillis(), setSoftMinEvictableIdleTimeMillis(long), Constant Field Values
- Constructor Detail
  - GenericObjectPool
```
public GenericObjectPool()
```
    Create a new GenericObjectPool with default properties.
  - GenericObjectPool
```
public GenericObjectPool(PoolableObjectFactory<T> factory)
```
    Create a new GenericObjectPool using the specified factory.
    
    Parameters:
    factory - the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects
  - GenericObjectPool
```
public GenericObjectPool(PoolableObjectFactory<T> factory,
                 GenericObjectPool.Config config)
```
    Create a new GenericObjectPool using the specified values.
    
    Parameters:
    factory - the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects
    config - a non-null GenericObjectPool.Config describing my configuration
  - GenericObjectPool
```
public GenericObjectPool(PoolableObjectFactory<T> factory,
                 int maxActive)
```
    Create a new GenericObjectPool using the specified values.
    
    Parameters:
    factory - the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects
    maxActive - the maximum number of objects that can be borrowed from me at one time (see setMaxActive(int))
  - GenericObjectPool
```
public GenericObjectPool(PoolableObjectFactory<T> factory,
                 int maxActive,
                 byte whenExhaustedAction,
                 long maxWait)
```
    Create a new GenericObjectPool using the specified values.
    
    Parameters:
    factory - the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects
    maxActive - the maximum number of objects that can be borrowed from me at one time (see setMaxActive(int))
    whenExhaustedAction - the action to take when the pool is exhausted (see getWhenExhaustedAction())
    maxWait - the maximum amount of time to wait for an idle object when the pool is exhausted an and whenExhaustedAction is WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see getMaxWait())
  - GenericObjectPool
```
public GenericObjectPool(PoolableObjectFactory<T> factory,
                 int maxActive,
                 byte whenExhaustedAction,
                 long maxWait,
                 boolean testOnBorrow,
                 boolean testOnReturn)
```
    Create a new GenericObjectPool using the specified values.
    
    Parameters:
    factory - the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects
    maxActive - the maximum number of objects that can be borrowed at one time (see setMaxActive(int))
    whenExhaustedAction - the action to take when the pool is exhausted (see getWhenExhaustedAction())
    maxWait - the maximum amount of time to wait for an idle object when the pool is exhausted an and whenExhaustedAction is WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see getMaxWait())
    testOnBorrow - whether or not to validate objects before they are returned by the borrowObject() method (see getTestOnBorrow())
    testOnReturn - whether or not to validate objects after they are returned to the returnObject(T) method (see getTestOnReturn())
  - GenericObjectPool
```
public GenericObjectPool(PoolableObjectFactory<T> factory,
                 int maxActive,
                 byte whenExhaustedAction,
                 long maxWait,
                 int maxIdle)
```
    Create a new GenericObjectPool using the specified values.
    
    Parameters:
    factory - the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects
    maxActive - the maximum number of objects that can be borrowed at one time (see setMaxActive(int))
    whenExhaustedAction - the action to take when the pool is exhausted (see getWhenExhaustedAction())
    maxWait - the maximum amount of time to wait for an idle object when the pool is exhausted and whenExhaustedAction is WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see getMaxWait())
    maxIdle - the maximum number of idle objects in my pool (see getMaxIdle())
  - GenericObjectPool
```
public GenericObjectPool(PoolableObjectFactory<T> factory,
                 int maxActive,
                 byte whenExhaustedAction,
                 long maxWait,
                 int maxIdle,
                 boolean testOnBorrow,
                 boolean testOnReturn)
```
    Create a new GenericObjectPool using the specified values.
    
    Parameters:
    factory - the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects
    maxActive - the maximum number of objects that can be borrowed at one time (see setMaxActive(int))
    whenExhaustedAction - the action to take when the pool is exhausted (see getWhenExhaustedAction())
    maxWait - the maximum amount of time to wait for an idle object when the pool is exhausted and whenExhaustedAction is WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see getMaxWait())
    maxIdle - the maximum number of idle objects in my pool (see getMaxIdle())
    testOnBorrow - whether or not to validate objects before they are returned by the borrowObject() method (see getTestOnBorrow())
    testOnReturn - whether or not to validate objects after they are returned to the returnObject(T) method (see getTestOnReturn())
  - GenericObjectPool
```
public GenericObjectPool(PoolableObjectFactory<T> factory,
                 int maxActive,
                 byte whenExhaustedAction,
                 long maxWait,
                 int maxIdle,
                 boolean testOnBorrow,
                 boolean testOnReturn,
                 long timeBetweenEvictionRunsMillis,
                 int numTestsPerEvictionRun,
                 long minEvictableIdleTimeMillis,
                 boolean testWhileIdle)
```
    Create a new GenericObjectPool using the specified values.
    
    Parameters:
    factory - the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects
    maxActive - the maximum number of objects that can be borrowed at one time (see setMaxActive(int))
    whenExhaustedAction - the action to take when the pool is exhausted (see setWhenExhaustedAction(byte))
    maxWait - the maximum amount of time to wait for an idle object when the pool is exhausted and whenExhaustedAction is WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see setMaxWait(long))
    maxIdle - the maximum number of idle objects in my pool (see setMaxIdle(int))
    testOnBorrow - whether or not to validate objects before they are returned by the borrowObject() method (see setTestOnBorrow(boolean))
    testOnReturn - whether or not to validate objects after they are returned to the returnObject(T) method (see setTestOnReturn(boolean))
    timeBetweenEvictionRunsMillis - the amount of time (in milliseconds) to sleep between examining idle objects for eviction (see setTimeBetweenEvictionRunsMillis(long))
    numTestsPerEvictionRun - the number of idle objects to examine per run within the idle object eviction thread (if any) (see setNumTestsPerEvictionRun(int))
    minEvictableIdleTimeMillis - the minimum number of milliseconds an object can sit idle in the pool before it is eligible for eviction (see setMinEvictableIdleTimeMillis(long))
    testWhileIdle - whether or not to validate objects in the idle object eviction thread, if any (see setTestWhileIdle(boolean))
  - GenericObjectPool
```
public GenericObjectPool(PoolableObjectFactory<T> factory,
                 int maxActive,
                 byte whenExhaustedAction,
                 long maxWait,
                 int maxIdle,
                 int minIdle,
                 boolean testOnBorrow,
                 boolean testOnReturn,
                 long timeBetweenEvictionRunsMillis,
                 int numTestsPerEvictionRun,
                 long minEvictableIdleTimeMillis,
                 boolean testWhileIdle)
```
    Create a new GenericObjectPool using the specified values.
    
    Parameters:
    factory - the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects
    maxActive - the maximum number of objects that can be borrowed at one time (see setMaxActive(int))
    whenExhaustedAction - the action to take when the pool is exhausted (see setWhenExhaustedAction(byte))
    maxWait - the maximum amount of time to wait for an idle object when the pool is exhausted and whenExhaustedAction is WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see setMaxWait(long))
    maxIdle - the maximum number of idle objects in my pool (see setMaxIdle(int))
    minIdle - the minimum number of idle objects in my pool (see setMinIdle(int))
    testOnBorrow - whether or not to validate objects before they are returned by the borrowObject() method (see setTestOnBorrow(boolean))
    testOnReturn - whether or not to validate objects after they are returned to the returnObject(T) method (see setTestOnReturn(boolean))
    timeBetweenEvictionRunsMillis - the amount of time (in milliseconds) to sleep between examining idle objects for eviction (see setTimeBetweenEvictionRunsMillis(long))
    numTestsPerEvictionRun - the number of idle objects to examine per run within the idle object eviction thread (if any) (see setNumTestsPerEvictionRun(int))
    minEvictableIdleTimeMillis - the minimum number of milliseconds an object can sit idle in the pool before it is eligible for eviction (see setMinEvictableIdleTimeMillis(long))
    testWhileIdle - whether or not to validate objects in the idle object eviction thread, if any (see setTestWhileIdle(boolean))
  - GenericObjectPool
```
public GenericObjectPool(PoolableObjectFactory<T> factory,
                 int maxActive,
                 byte whenExhaustedAction,
                 long maxWait,
                 int maxIdle,
                 int minIdle,
                 boolean testOnBorrow,
                 boolean testOnReturn,
                 long timeBetweenEvictionRunsMillis,
                 int numTestsPerEvictionRun,
                 long minEvictableIdleTimeMillis,
                 boolean testWhileIdle,
                 long softMinEvictableIdleTimeMillis)
```
    Create a new GenericObjectPool using the specified values.
    
    Parameters:
    factory - the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects
    maxActive - the maximum number of objects that can be borrowed at one time (see setMaxActive(int))
    whenExhaustedAction - the action to take when the pool is exhausted (see setWhenExhaustedAction(byte))
    maxWait - the maximum amount of time to wait for an idle object when the pool is exhausted and whenExhaustedAction is WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see setMaxWait(long))
    maxIdle - the maximum number of idle objects in my pool (see setMaxIdle(int))
    minIdle - the minimum number of idle objects in my pool (see setMinIdle(int))
    testOnBorrow - whether or not to validate objects before they are returned by the borrowObject() method (see setTestOnBorrow(boolean))
    testOnReturn - whether or not to validate objects after they are returned to the returnObject(T) method (see setTestOnReturn(boolean))
    timeBetweenEvictionRunsMillis - the amount of time (in milliseconds) to sleep between examining idle objects for eviction (see setTimeBetweenEvictionRunsMillis(long))
    numTestsPerEvictionRun - the number of idle objects to examine per run within the idle object eviction thread (if any) (see setNumTestsPerEvictionRun(int))
    minEvictableIdleTimeMillis - the minimum number of milliseconds an object can sit idle in the pool before it is eligible for eviction (see setMinEvictableIdleTimeMillis(long))
    testWhileIdle - whether or not to validate objects in the idle object eviction thread, if any (see setTestWhileIdle(boolean))
    softMinEvictableIdleTimeMillis - the minimum number of milliseconds an object can sit idle in the pool before it is eligible for eviction with the extra condition that at least "minIdle" amount of object remain in the pool. (see setSoftMinEvictableIdleTimeMillis(long))
    Since:
    
    Pool 1.3
  - GenericObjectPool
```
public GenericObjectPool(PoolableObjectFactory<T> factory,
                 int maxActive,
                 byte whenExhaustedAction,
                 long maxWait,
                 int maxIdle,
                 int minIdle,
                 boolean testOnBorrow,
                 boolean testOnReturn,
                 long timeBetweenEvictionRunsMillis,
                 int numTestsPerEvictionRun,
                 long minEvictableIdleTimeMillis,
                 boolean testWhileIdle,
                 long softMinEvictableIdleTimeMillis,
                 boolean lifo)
```
    Create a new GenericObjectPool using the specified values.
    
    Parameters:
    factory - the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects
    maxActive - the maximum number of objects that can be borrowed at one time (see setMaxActive(int))
    whenExhaustedAction - the action to take when the pool is exhausted (see setWhenExhaustedAction(byte))
    maxWait - the maximum amount of time to wait for an idle object when the pool is exhausted and whenExhaustedAction is WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see setMaxWait(long))
    maxIdle - the maximum number of idle objects in my pool (see setMaxIdle(int))
    minIdle - the minimum number of idle objects in my pool (see setMinIdle(int))
    testOnBorrow - whether or not to validate objects before they are returned by the borrowObject() method (see setTestOnBorrow(boolean))
    testOnReturn - whether or not to validate objects after they are returned to the returnObject(T) method (see setTestOnReturn(boolean))
    timeBetweenEvictionRunsMillis - the amount of time (in milliseconds) to sleep between examining idle objects for eviction (see setTimeBetweenEvictionRunsMillis(long))
    numTestsPerEvictionRun - the number of idle objects to examine per run within the idle object eviction thread (if any) (see setNumTestsPerEvictionRun(int))
    minEvictableIdleTimeMillis - the minimum number of milliseconds an object can sit idle in the pool before it is eligible for eviction (see setMinEvictableIdleTimeMillis(long))
    testWhileIdle - whether or not to validate objects in the idle object eviction thread, if any (see setTestWhileIdle(boolean))
    softMinEvictableIdleTimeMillis - the minimum number of milliseconds an object can sit idle in the pool before it is eligible for eviction with the extra condition that at least "minIdle" amount of object remain in the pool. (see setSoftMinEvictableIdleTimeMillis(long))
    lifo - whether or not objects are returned in last-in-first-out order from the idle object pool (see setLifo(boolean))
    Since:
    
    Pool 1.4
- Method Detail
  - getMaxActive
```
public int getMaxActive()
```
    Returns the maximum number of objects that can be allocated by the pool (checked out to clients, or idle awaiting checkout) at a given time. When non-positive, there is no limit to the number of objects that can be managed by the pool at one time.
    
    Returns:
    the cap on the total number of object instances managed by the pool.
    See Also:
    setMaxActive(int)
  - setMaxActive
```
public void setMaxActive(int maxActive)
```
    Sets the cap on the number of objects that can be allocated by the pool (checked out to clients, or idle awaiting checkout) at a given time. Use a negative value for no limit.
    
    Parameters:
    maxActive - The cap on the total number of object instances managed by the pool. Negative values mean that there is no limit to the number of objects allocated by the pool.
    See Also:
    getMaxActive()
  - getWhenExhaustedAction
```
public byte getWhenExhaustedAction()
```
    Returns the action to take when the borrowObject() method is invoked when the pool is exhausted (the maximum number of "active" objects has been reached).
    
    Returns:
    one of WHEN_EXHAUSTED_BLOCK, WHEN_EXHAUSTED_FAIL or WHEN_EXHAUSTED_GROW
    See Also:
    setWhenExhaustedAction(byte)
  - setWhenExhaustedAction
```
public void setWhenExhaustedAction(byte whenExhaustedAction)
```
    Sets the action to take when the borrowObject() method is invoked when the pool is exhausted (the maximum number of "active" objects has been reached).
    
    Parameters:
    whenExhaustedAction - the action code, which must be one of WHEN_EXHAUSTED_BLOCK, WHEN_EXHAUSTED_FAIL, or WHEN_EXHAUSTED_GROW
    See Also:
    getWhenExhaustedAction()
  - getMaxWait
```
public long getMaxWait()
```
    Returns the maximum amount of time (in milliseconds) the borrowObject() method should block before throwing an exception when the pool is exhausted and the "when exhausted" action is WHEN_EXHAUSTED_BLOCK. When less than or equal to 0, the borrowObject() method may block indefinitely.
    
    Returns:
    maximum number of milliseconds to block when borrowing an object.
    See Also:
    setMaxWait(long), setWhenExhaustedAction(byte), WHEN_EXHAUSTED_BLOCK
  - setMaxWait
```
public void setMaxWait(long maxWait)
```
    Sets the maximum amount of time (in milliseconds) the borrowObject() method should block before throwing an exception when the pool is exhausted and the "when exhausted" action is WHEN_EXHAUSTED_BLOCK. When less than or equal to 0, the borrowObject() method may block indefinitely.
    
    Parameters:
    maxWait - maximum number of milliseconds to block when borrowing an object.
    See Also:
    getMaxWait(), setWhenExhaustedAction(byte), WHEN_EXHAUSTED_BLOCK
  - getMaxIdle
```
public int getMaxIdle()
```
    Returns the cap on the number of "idle" instances in the pool.
    
    Returns:
    the cap on the number of "idle" instances in the pool.
    See Also:
    setMaxIdle(int)
  - setMaxIdle
```
public void setMaxIdle(int maxIdle)
```
    Sets the cap on the number of "idle" instances in the pool. If maxIdle is set too low on heavily loaded systems it is possible you will see objects being destroyed and almost immediately new objects being created. This is a result of the active threads momentarily returning objects faster than they are requesting them them, causing the number of idle objects to rise above maxIdle. The best value for maxIdle for heavily loaded system will vary but the default is a good starting point.
    
    Parameters:
    maxIdle - The cap on the number of "idle" instances in the pool. Use a negative value to indicate an unlimited number of idle instances.
    See Also:
    getMaxIdle()
  - setMinIdle
```
public void setMinIdle(int minIdle)
```
    Sets the minimum number of objects allowed in the pool before the evictor thread (if active) spawns new objects. Note that no objects are created when numActive + numIdle >= maxActive. This setting has no effect if the idle object evictor is disabled (i.e. if timeBetweenEvictionRunsMillis <= 0).
    If the configured value of minIdle is greater than the configured value for maxIdle then the value of maxIdle will be used instead.
    
    Parameters:
    minIdle - The minimum number of objects.
    See Also:
    getMinIdle(), getTimeBetweenEvictionRunsMillis()
  - getMinIdle
```
public int getMinIdle()
```
    Returns the minimum number of objects allowed in the pool before the evictor thread (if active) spawns new objects. (Note no objects are created when: numActive + numIdle >= maxActive)
    If the configured value of minIdle is greater than the configured value for maxIdle then the value of maxIdle will be used instead.
    
    Returns:
    The minimum number of objects.
    See Also:
    setMinIdle(int)
  - getTestOnBorrow
```
public boolean getTestOnBorrow()
```
    When true, objects will be validated before being returned by the borrowObject() method. If the object fails to validate, it will be dropped from the pool, and we will attempt to borrow another.
    
    Returns:
    true if objects are validated before being borrowed.
    See Also:
    setTestOnBorrow(boolean)
  - setTestOnBorrow
```
public void setTestOnBorrow(boolean testOnBorrow)
```
    When true, objects will be validated before being returned by the borrowObject() method. If the object fails to validate, it will be dropped from the pool, and we will attempt to borrow another.
    
    Parameters:
    testOnBorrow - true if objects should be validated before being borrowed.
    See Also:
    getTestOnBorrow()
  - getTestOnReturn
```
public boolean getTestOnReturn()
```
    When true, objects will be validated before being returned to the pool within the returnObject(T).
    
    Returns:
    true when objects will be validated after returned to returnObject(T).
    See Also:
    setTestOnReturn(boolean)
  - setTestOnReturn
```
public void setTestOnReturn(boolean testOnReturn)
```
    When true, objects will be validated before being returned to the pool within the returnObject(T).
    
    Parameters:
    testOnReturn - true so objects will be validated after returned to returnObject(T).
    See Also:
    getTestOnReturn()
  - getTimeBetweenEvictionRunsMillis
```
public long getTimeBetweenEvictionRunsMillis()
```
    Returns the number of milliseconds to sleep between runs of the idle object evictor thread. When non-positive, no idle object evictor thread will be run.
    
    Returns:
    number of milliseconds to sleep between evictor runs.
    See Also:
    setTimeBetweenEvictionRunsMillis(long)
  - setTimeBetweenEvictionRunsMillis
```
public void setTimeBetweenEvictionRunsMillis(long timeBetweenEvictionRunsMillis)
```
    Sets the number of milliseconds to sleep between runs of the idle object evictor thread. When non-positive, no idle object evictor thread will be run.
    
    Parameters:
    timeBetweenEvictionRunsMillis - number of milliseconds to sleep between evictor runs.
    See Also:
    getTimeBetweenEvictionRunsMillis()
  - getNumTestsPerEvictionRun
```
public int getNumTestsPerEvictionRun()
```
    Returns the max number of objects to examine during each run of the idle object evictor thread (if any).
    
    Returns:
    max number of objects to examine during each evictor run.
    See Also:
    setNumTestsPerEvictionRun(int), setTimeBetweenEvictionRunsMillis(long)
  - setNumTestsPerEvictionRun
```
public void setNumTestsPerEvictionRun(int numTestsPerEvictionRun)
```
    Sets the max number of objects to examine during each run of the idle object evictor thread (if any).
    When a negative value is supplied, ceil(getNumIdle())/abs(getNumTestsPerEvictionRun()) tests will be run. That is, when the value is -n, roughly one nth of the idle objects will be tested per run. When the value is positive, the number of tests actually performed in each run will be the minimum of this value and the number of instances idle in the pool.
    
    Parameters:
    numTestsPerEvictionRun - max number of objects to examine during each evictor run.
    See Also:
    getNumTestsPerEvictionRun(), setTimeBetweenEvictionRunsMillis(long)
  - getMinEvictableIdleTimeMillis
```
public long getMinEvictableIdleTimeMillis()
```
    Returns the minimum amount of time an object may sit idle in the pool before it is eligible for eviction by the idle object evictor (if any).
    
    Returns:
    minimum amount of time an object may sit idle in the pool before it is eligible for eviction.
    See Also:
    setMinEvictableIdleTimeMillis(long), setTimeBetweenEvictionRunsMillis(long)
  - setMinEvictableIdleTimeMillis
```
public void setMinEvictableIdleTimeMillis(long minEvictableIdleTimeMillis)
```
    Sets the minimum amount of time an object may sit idle in the pool before it is eligible for eviction by the idle object evictor (if any). When non-positive, no objects will be evicted from the pool due to idle time alone.
    
    Parameters:
    minEvictableIdleTimeMillis - minimum amount of time an object may sit idle in the pool before it is eligible for eviction.
    See Also:
    getMinEvictableIdleTimeMillis(), setTimeBetweenEvictionRunsMillis(long)
  - getSoftMinEvictableIdleTimeMillis
```
public long getSoftMinEvictableIdleTimeMillis()
```
    Returns the minimum amount of time an object may sit idle in the pool before it is eligible for eviction by the idle object evictor (if any), with the extra condition that at least "minIdle" amount of object remain in the pool.
    
    Returns:
    minimum amount of time an object may sit idle in the pool before it is eligible for eviction.
    Since:
    
    Pool 1.3
    
    See Also:
    setSoftMinEvictableIdleTimeMillis(long)
  - setSoftMinEvictableIdleTimeMillis
```
public void setSoftMinEvictableIdleTimeMillis(long softMinEvictableIdleTimeMillis)
```
    Sets the minimum amount of time an object may sit idle in the pool before it is eligible for eviction by the idle object evictor (if any), with the extra condition that at least "minIdle" object instances remain in the pool. When non-positive, no objects will be evicted from the pool due to idle time alone.
    
    Parameters:
    softMinEvictableIdleTimeMillis - minimum amount of time an object may sit idle in the pool before it is eligible for eviction.
    Since:
    
    Pool 1.3
    
    See Also:
    getSoftMinEvictableIdleTimeMillis()
  - getTestWhileIdle
```
public boolean getTestWhileIdle()
```
    When true, objects will be validated by the idle object evictor (if any). If an object fails to validate, it will be dropped from the pool.
    
    Returns:
    true when objects will be validated by the evictor.
    See Also:
    setTestWhileIdle(boolean), setTimeBetweenEvictionRunsMillis(long)
  - setTestWhileIdle
```
public void setTestWhileIdle(boolean testWhileIdle)
```
    When true, objects will be validated by the idle object evictor (if any). If an object fails to validate, it will be dropped from the pool.
    
    Parameters:
    testWhileIdle - true so objects will be validated by the evictor.
    See Also:
    getTestWhileIdle(), setTimeBetweenEvictionRunsMillis(long)
  - getLifo
```
public boolean getLifo()
```
    Whether or not the idle object pool acts as a LIFO queue. True means that borrowObject returns the most recently used ("last in") idle object in the pool (if there are idle instances available). False means that the pool behaves as a FIFO queue - objects are taken from the idle object pool in the order that they are returned to the pool.
    
    Returns:
    true if the pool is configured to act as a LIFO queue
    Since:
    
    1.4
  - setLifo
```
public void setLifo(boolean lifo)
```
    Sets the LIFO property of the pool. True means that borrowObject returns the most recently used ("last in") idle object in the pool (if there are idle instances available). False means that the pool behaves as a FIFO queue - objects are taken from the idle object pool in the order that they are returned to the pool.
    
    Parameters:
    lifo - the new value for the LIFO property
    Since:
    
    1.4
  - setConfig
```
public void setConfig(GenericObjectPool.Config conf)
```
    Sets my configuration.
    
    Parameters:
    conf - configuration to use.
    See Also:
    GenericObjectPool.Config
  - borrowObject
```
public T borrowObject()
               throws Exception
```
    Borrows an object from the pool.
    
    If there is an idle instance available in the pool, then either the most-recently returned (if lifo == true) or "oldest" (lifo == false) instance sitting idle in the pool will be activated and returned. If activation fails, or testOnBorrow is set to true and validation fails, the instance is destroyed and the next available instance is examined. This continues until either a valid instance is returned or there are no more idle instances available.
    
    If there are no idle instances available in the pool, behavior depends on the maxActive and (if applicable) whenExhaustedAction and maxWait properties. If the number of instances checked out from the pool is less than maxActive, a new instance is created, activated and (if applicable) validated and returned to the caller.
    
    If the pool is exhausted (no available idle instances and no capacity to create new ones), this method will either block (WHEN_EXHAUSTED_BLOCK), throw a NoSuchElementException (WHEN_EXHAUSTED_FAIL), or grow (WHEN_EXHAUSTED_GROW - ignoring maxActive). The length of time that this method will block when whenExhaustedAction == WHEN_EXHAUSTED_BLOCK is determined by the maxWait property.
    
    When the pool is exhausted, multiple calling threads may be simultaneously blocked waiting for instances to become available. As of pool 1.5, a "fairness" algorithm has been implemented to ensure that threads receive available instances in request arrival order.
    
    Specified by:
    
    borrowObject in interface ObjectPool<T>
    
    Specified by:
    
    borrowObject in class BaseObjectPool<T>
    
    Returns:
    object instance
    
    Throws:
    
    NoSuchElementException - if an instance cannot be returned
    
    Exception - if an instance cannot be obtained from the pool
  - invalidateObject
```
public void invalidateObject(T obj)
                      throws Exception
```
    Invalidates an object from the pool.
    
    By contract, obj must have been obtained using borrowObject.
    
    This method should be used when an object that has been borrowed is determined (due to an exception or other problem) to be invalid.
    
    Activation of this method decrements the active count and attempts to destroy the instance.
    
    Specified by:
    
    invalidateObject in interface ObjectPool<T>
    
    Specified by:
    
    invalidateObject in class BaseObjectPool<T>
    
    Parameters:
    obj - a borrowed instance to be disposed.
    
    Throws:
    
    Exception - if the configured PoolableObjectFactory throws an exception destroying obj
  - clear
```
public void clear()
```
    Clears any objects sitting idle in the pool by removing them from the idle instance pool and then invoking the configured PoolableObjectFactory.destroyObject(Object) method on each idle instance.
    Implementation notes:
    - This method does not destroy or effect in any way instances that are checked out of the pool when it is invoked.
    - Invoking this method does not prevent objects being returned to the idle instance pool, even during its execution. It locks the pool only during instance removal. Additional instances may be returned while removed items are being destroyed.
    - Exceptions encountered destroying idle instances are swallowed.
    Specified by:
    
    clear in interface ObjectPool<T>
    
    Overrides:
    
    clear in class BaseObjectPool<T>
  - getNumActive
```
public int getNumActive()
```
    Return the number of instances currently borrowed from this pool.
    
    Specified by:
    
    getNumActive in interface ObjectPool<T>
    
    Overrides:
    
    getNumActive in class BaseObjectPool<T>
    
    Returns:
    the number of instances currently borrowed from this pool
  - getNumIdle
```
public int getNumIdle()
```
    Return the number of instances currently idle in this pool.
    
    Specified by:
    
    getNumIdle in interface ObjectPool<T>
    
    Overrides:
    
    getNumIdle in class BaseObjectPool<T>
    
    Returns:
    the number of instances currently idle in this pool
  - returnObject
```
public void returnObject(T obj)
                  throws Exception
```
    Returns an object instance to the pool.
    
    If maxIdle is set to a positive value and the number of idle instances has reached this value, the returning instance is destroyed.
    
    If testOnReturn == true, the returning instance is validated before being returned to the idle instance pool. In this case, if validation fails, the instance is destroyed.
    
    Note: There is no guard to prevent an object being returned to the pool multiple times. Clients are expected to discard references to returned objects and ensure that an object is not returned to the pool multiple times in sequence (i.e., without being borrowed again between returns). Violating this contract will result in the same object appearing multiple times in the pool and pool counters (numActive, numIdle) returning incorrect values.
    
    Specified by:
    
    returnObject in interface ObjectPool<T>
    
    Specified by:
    
    returnObject in class BaseObjectPool<T>
    
    Parameters:
    obj - instance to return to the pool
    
    Throws:
    
    Exception
  - close
```
public void close()
           throws Exception
```
    Closes the pool. Once the pool is closed, borrowObject() will fail with IllegalStateException, but returnObject(Object) and invalidateObject(Object) will continue to work, with returned objects destroyed on return.
    
    Destroys idle instances in the pool by invoking clear().
    
    Specified by:
    
    close in interface ObjectPool<T>
    
    Overrides:
    
    close in class BaseObjectPool<T>
    
    Throws:
    
    Exception
  - setFactory
```
@Deprecated
public void setFactory(PoolableObjectFactory<T> factory)
                throws IllegalStateException
```
    Deprecated. to be removed in version 2.0
    
    Sets the factory this pool uses to create new instances. Trying to change the factory while there are borrowed objects will throw an IllegalStateException. If there are instances idle in the pool when this method is invoked, these will be destroyed using the original factory.
    
    Specified by:
    
    setFactory in interface ObjectPool<T>
    
    Overrides:
    
    setFactory in class BaseObjectPool<T>
    
    Parameters:
    factory - the PoolableObjectFactory used to create new instances.
    
    Throws:
    
    IllegalStateException - when the factory cannot be set at this time
  - evict
```
public void evict()
           throws Exception
```
    Perform numTests idle object eviction tests, evicting examined objects that meet the criteria for eviction. If testWhileIdle is true, examined objects are validated when visited (and removed if invalid); otherwise only objects that have been idle for more than minEvicableIdletimeMillis are removed.
    
    Successive activations of this method examine objects in in sequence, cycling through objects in oldest-to-youngest order.
    
    Throws:
    
    Exception - if the pool is closed or eviction fails.
  - addObject
```
public void addObject()
               throws Exception
```
    Create an object, and place it into the pool. addObject() is useful for "pre-loading" a pool with idle objects.
    
    Specified by:
    
    addObject in interface ObjectPool<T>
    
    Overrides:
    
    addObject in class BaseObjectPool<T>
    
    Throws:
    
    Exception - when PoolableObjectFactory.makeObject() fails.
    
    IllegalStateException - after ObjectPool.close() has been called on this pool.
    
    UnsupportedOperationException - when this pool cannot add new idle objects.
  - startEvictor
```
protected void startEvictor(long delay)
```
    Start the eviction thread or service, or when delay is non-positive, stop it if it is already running.
    
    Parameters:
    delay - milliseconds between evictor runs.

Class GenericObjectPool<T>

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class org.apache.tomcat.dbcp.pool.BaseObjectPool

Methods inherited from class java.lang.Object

Field Detail

WHEN_EXHAUSTED_FAIL

WHEN_EXHAUSTED_BLOCK

WHEN_EXHAUSTED_GROW

DEFAULT_MAX_IDLE

DEFAULT_MIN_IDLE

DEFAULT_MAX_ACTIVE

DEFAULT_WHEN_EXHAUSTED_ACTION

DEFAULT_LIFO

DEFAULT_MAX_WAIT

DEFAULT_TEST_ON_BORROW

DEFAULT_TEST_ON_RETURN

DEFAULT_TEST_WHILE_IDLE

DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS

DEFAULT_NUM_TESTS_PER_EVICTION_RUN

DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS

DEFAULT_SOFT_MIN_EVICTABLE_IDLE_TIME_MILLIS

Constructor Detail

GenericObjectPool

GenericObjectPool

GenericObjectPool

GenericObjectPool

GenericObjectPool

GenericObjectPool

GenericObjectPool

GenericObjectPool

GenericObjectPool

GenericObjectPool

GenericObjectPool

GenericObjectPool

Method Detail

getMaxActive

setMaxActive

getWhenExhaustedAction

setWhenExhaustedAction

getMaxWait

setMaxWait

getMaxIdle

setMaxIdle

setMinIdle

getMinIdle

getTestOnBorrow

setTestOnBorrow

getTestOnReturn

setTestOnReturn

getTimeBetweenEvictionRunsMillis

setTimeBetweenEvictionRunsMillis

getNumTestsPerEvictionRun

setNumTestsPerEvictionRun

getMinEvictableIdleTimeMillis

setMinEvictableIdleTimeMillis

getSoftMinEvictableIdleTimeMillis

setSoftMinEvictableIdleTimeMillis

getTestWhileIdle

setTestWhileIdle

getLifo

setLifo

setConfig

borrowObject

invalidateObject

clear

getNumActive

getNumIdle

returnObject

close

setFactory

evict

addObject

startEvictor