Commons POOL Version 1.4 
                                 RELEASE NOTES
      
This is a maintenance release including numerous bug fixes. This release is 
source and binary compatible with version 1.3 of commons pool, but there are 
some behavior changes introduced to resolve bugs, remove ambiguity or improve 
robustness. Among these are the change in default behavior of 
GenericObjectPool and GenericKeyedObjectPool from FIFO back to LIFO queues (as 
in 1.2 and earlier). The LIFO/FIFO behavior is now configurable. Some of the 
extra synchronization included in version 1.3 was removed / refactored to 
improve performance. The javadoc has also been made more complete and 
explicit. See the detailed list of changes below for specifics on fixed bugs 
and behavior changes in Commons Pool 1.4. This version of Commons Pool depends 
only on JDK version 1.3 or higher. Classes implementing pools are all intended 
to be threadsafe. 
      
                             SUMMARY OF CHANGES

BUG FIXES

o Fixed constructor which was ignoring maxTotal parameter: 
  GenericKeyedObjectPool(KeyedPoolableObjectFactory factory, int maxActive, 
  byte whenExhaustedAction, long maxWait, int maxIdle, int maxTotal, boolean 
  testOnBorrow, boolean testOnReturn, long timeBetweenEvictionRunsMillis, int 
  numTestsPerEvictionRun, long minEvictableIdleTimeMillis, boolean 
  testWhileIdle) 
o Changed StackKeyedObjectPool to discard stalest, not freshest, idle object 
  when maxSleeping is reached. 
o Allowed blocked threads in GenericObjectPool borrowObject to be 
  interrupted. Issue: POOL-102. Thanks to John Sumsion. 
o Fixes to address idle object eviction and LIFO/FIFO behavior reported in 
  POOL-86. Made LIFO/FIFO behavior configurable for GenericObjectPool and 
  GenericKeyedObjectPool, with default set back to LIFO (reverting to 1.2 
  behavior). Fixed GOP, GKOP evict method and added tests to ensure objects 
  are visited in oldest-to-youngest order. Changed backing store for GOP, 
  GKOP pools back to Commons Collections CursorableLinkedList (brought this 
  class in, repackaged with package scope). Issue: POOL-86. 
o Changed the default setting for Config.softMinEvictableIdleTimeMillis to 
  GenericObjectPool.DEFAULT_SOFT_MIN_EVICTABLE_IDLE_TIME_MILLIS (was being 
  incorrectly defaulted to DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS). Issue: 
  POOL-110. Thanks to Alexander Pogrebnyak. 
o Added a wrapper for the shared idle object eviction timer for all pools. 
  The wrapper class wraps the Timer and keeps track of how many pools are 
  using it. If no pools are using the timer, it is canceled. This prevents a 
  thread being left running which, in application server environments, can 
  lead to memory leaks and/or prevent applications from shutting down or 
  reloading cleanly. Issue: POOL-97. Thanks to Mark Thomas. 
o Reduced synchronization in GenericObjectPool, GenericKeyedObjectPool. 
  Factory method activations within synchronized blocks were causing 
  performance problems in DBCP and other applications where factory methods 
  could block. Fixes both POOL-93 and POOL-108. Issue: POOL-93. Thanks to 
  Mark Thomas. 
o Made _testOnBorrow, _testOnReturn volatile and removed synchronization in 
  associated getters and setters in GenericObjectPool, 
  GenericKeyedObjectPool. Made getNumIdle synchronized in 
  StackKeyedObjectPool. Issue: POOL-113. 
o Fixed an error in the GenericKeyedObjectPool constructor that takes a 
  Config instance as a parameter. The minIdle setting in the Config was being 
  ignored by the constructor. Issue: POOL-116. 
o Made behavior on instance validation failure consistent across pools, 
  eliminating possible infinite loops in StackObjectPool, 
  StackKeyedObjectPool, SoftReferenceObjectPool when factory fails to create 
  valid objects. Issue: POOL-117. 

BEHAVIOR CHANGES

o When no factory has been defined, addObject now throws 
  IllegalStateExecption instead of NullPointerException for all pools. 
o SoftReferenceObjectPool. Improved the accuracy of getNumIdle by "pruning" 
  references to objects that have been garbage collected. 
o GenericObjectPool, GenericKeyedObjectPool, SoftReferenceObjectPool, 
  StackObjectPool. Eliminated IllegalStateExceptions when the following 
  operations are attempted on a closed pool: getNumActive, getNumIdle, 
  returnObject, invalidateObject. In each case, the operation is allowed to 
  proceed, reporting the state of the pool that is being shut down, or 
  destroying objects returning to the closed pool. 
o StackObjectPool, SoftReferenceObjectPool, GenericKeyedObjectPool. Allowed 
  borrowObject to continue (either examining additional idle instances or 
  with makeObject) when an exception is encountered activating an idle object 
  instead of propagating the exception to the client. Also made addObject 
  propagate (not swallow) exceptions when passivating newly created 
  instances. 
o StackKeyedObjectPool. Added validation check for objects returned from 
  borrowObject. 
o BaseObjectPool, BaseKeyedObjectPool. Instead of throwing 
  UnsupportedOperationException, the base class implementations of getNumIdle 
  and getNumActive return negative values. The base implementation of close 
  in BaseObjectPool no longer throws IllegalStateException when invoked on an 
  already closed pool. 

For more information on Commons Pool, see
http://commons.apache.org/pool/