bruno 2003/09/04 01:12:33
Modified: event/src/java/org/apache/excalibur/event/command
TPCThreadManager.java
Log:
* fixed the problem Carsten's committed in the previous version in a
different way (BTW, it isn't servlet-related)
(see comment inline)
* made the keep-alive-time of the PooledExecutor configurable, instead
of taking the sleeptime. This makes the condition that the threadpool
is one below its maximum capacity much less likely to occur.
Default is 5 minutes.
Revision Changes Path
1.43 +26 -3
avalon-excalibur/event/src/java/org/apache/excalibur/event/command/TPCThreadManager.java
Index: TPCThreadManager.java
===================================================================
RCS file:
/home/cvs/avalon-excalibur/event/src/java/org/apache/excalibur/event/command/TPCThreadManager.java,v
retrieving revision 1.42
retrieving revision 1.43
diff -u -r1.42 -r1.43
--- TPCThreadManager.java 3 Sep 2003 13:42:54 -0000 1.42
+++ TPCThreadManager.java 4 Sep 2003 08:12:33 -0000 1.43
@@ -71,6 +71,7 @@
private PooledExecutor m_threadPool;
private int m_processors = -1;
private int m_threadsPerProcessor = 1;
+ private int m_keepAliveTime = 300000;
private boolean m_hardShutdown = false;
/**
@@ -96,6 +97,11 @@
* <td>1000</td>
* </tr>
* <tr>
+ * <td>keep-alive-time</td>
+ * <td>Time (in milliseconds) that idle threads should remain in the
threadpool</td>
+ * <td>300000</td>
+ * </tr>
+ * <tr>
* <td>force-shutdown</td>
* <td>At shutdown time, allow currently queued tasks to finish, or
immediately quit</td>
* <td>false</td>
@@ -113,6 +119,8 @@
m_threadsPerProcessor =
Math.max( parameters.getParameterAsInteger( "threads-per-processor", 1
), 1 );
+ m_keepAliveTime = parameters.getParameterAsInteger("keep-alive-time",
300000);
+
setSleepTime( parameters.getParameterAsLong( "sleep-time", 1000L ) );
m_hardShutdown = ( parameters.getParameterAsBoolean( "force-shutdown",
false ) );
@@ -130,11 +138,26 @@
throw new IllegalStateException( "ThreadManager is already initailized"
);
}
+ final int maxPoolSize = ( m_processors * m_threadsPerProcessor ) + 1;
m_threadPool = new PooledExecutor( m_processors + 1 );
m_threadPool.setMinimumPoolSize( 2 ); // at least two threads
- m_threadPool.setMaximumPoolSize( ( m_processors * m_threadsPerProcessor ) +
1 );
- m_threadPool.setKeepAliveTime( getSleepTime() );
- m_threadPool.discardWhenBlocked();
+ m_threadPool.setMaximumPoolSize( maxPoolSize );
+ m_threadPool.waitWhenBlocked();
+ if (maxPoolSize == 2) {
+ // The PooledExecutor has an inherent race condition between releasing
threads
+ // and adding new tasks (when using the waitWhenBlocked policy):
+ // it could be that a thread is being released while a new
+ // task is being added. That task would then remain waiting to be
picked up by
+ // the next thread that becomes available, but meanwhile the threadpool
is below its maximum capacity.
+ // If the threadpool has a maximum size of 1, then this could leave the
task waiting forever.
+ // Here we check if maxPoolSize == 2 because one of the threads used by
the threadpool will
+ // be used continuously by the ThreadManager itself.
+ // As a solution to this problem, the one available work-thread we have
in this case
+ // is set to never expire.
+ m_threadPool.setKeepAliveTime( -1 );
+ } else {
+ m_threadPool.setKeepAliveTime( m_keepAliveTime );
+ }
if( null == getLogger() )
{
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