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Posted to dev@uima.apache.org by "Timo Boehme (JIRA)" <de...@uima.apache.org> on 2010/10/22 10:00:18 UTC
[jira] Created: (UIMA-1906) Daemon thread prevents CPE exit
Daemon thread prevents CPE exit
-------------------------------
Key: UIMA-1906
URL: https://issues.apache.org/jira/browse/UIMA-1906
Project: UIMA
Issue Type: Bug
Components: Collection Processing
Affects Versions: 2.3
Reporter: Timo Boehme
If a daemon thread was started within an AE and keeps running independent of the AE processing (e.g. bound to a static variable) it prevents exiting of the CPE.
Simple test:
add following class to a AE:
static class DaemonThread implements Runnable {
private static volatile Thread threadInstance;
/** Creates a daemon thread if it not already exists. */
public synchronized static void startThread() {
if ( threadInstance == null ) {
threadInstance = new Thread( new DaemonThread(), "TestDaemon" );
threadInstance.setDaemon( true );
threadInstance.start();
}
}
@Override
public void run() {
while ( true ) {
try { Thread.sleep( 2000 ); } catch ( InterruptedException ie ) {}
}
}
}
and call DaemonThread.startThread(); within the process() method.
After CPE signals collectionProcesscomplete() the application does not exit.
The reason: in org.apache.uima.collection.impl.cpm.engine.CPMEngine a threadGroupDestroyer thread is created (line 2522) which waits for threads to die. Since it does not check for daemon threads it counts them as normal threads to wait for and thus it waits forever (this can be seen with kill -3 PID to get a JAVA stack trace of all threads under UNIX).
A workaround would be to put the daemon thread in another ThreadGroup. In the example if you create the tread with
ThreadGroup parent = Thread.currentThread().getThreadGroup();
while ( parent.getParent() != null )
parent = parent.getParent();
threadInstance = new Thread( parent, new DaemonThread(), "TestDaemon" );
(in the top most thread group) the CPE exits normally.
However this is not possible with closed source libraries.
Thus the threadGroupDestroyer must test for daemon threads. Furthermore the used group.activeCount() (in org.apache.uima.collection.impl.cpm.engine.CPMEngine) should only be used for information purposes - as the javadoc states - not for relying on it as a loop parameter.
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[jira] Commented: (UIMA-1906) Daemon thread prevents CPE exit
Posted by "Marshall Schor (JIRA)" <de...@uima.apache.org>.
[ https://issues.apache.org/jira/browse/UIMA-1906?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12923847#action_12923847 ]
Marshall Schor commented on UIMA-1906:
--------------------------------------
Thanks, Timo. Can you provide a patch for this?
> Daemon thread prevents CPE exit
> -------------------------------
>
> Key: UIMA-1906
> URL: https://issues.apache.org/jira/browse/UIMA-1906
> Project: UIMA
> Issue Type: Bug
> Components: Collection Processing
> Affects Versions: 2.3
> Reporter: Timo Boehme
>
> If a daemon thread was started within an AE and keeps running independent of the AE processing (e.g. bound to a static variable) it prevents exiting of the CPE.
> Simple test:
> add following class to a AE:
> static class DaemonThread implements Runnable {
> private static volatile Thread threadInstance;
> /** Creates a daemon thread if it not already exists. */
> public synchronized static void startThread() {
> if ( threadInstance == null ) {
> threadInstance = new Thread( new DaemonThread(), "TestDaemon" );
> threadInstance.setDaemon( true );
> threadInstance.start();
> }
> }
> @Override
> public void run() {
> while ( true ) {
> try { Thread.sleep( 2000 ); } catch ( InterruptedException ie ) {}
> }
> }
> }
> and call DaemonThread.startThread(); within the process() method.
> After CPE signals collectionProcesscomplete() the application does not exit.
> The reason: in org.apache.uima.collection.impl.cpm.engine.CPMEngine a threadGroupDestroyer thread is created (line 2522) which waits for threads to die. Since it does not check for daemon threads it counts them as normal threads to wait for and thus it waits forever (this can be seen with kill -3 PID to get a JAVA stack trace of all threads under UNIX).
> A workaround would be to put the daemon thread in another ThreadGroup. In the example if you create the tread with
> ThreadGroup parent = Thread.currentThread().getThreadGroup();
> while ( parent.getParent() != null )
> parent = parent.getParent();
> threadInstance = new Thread( parent, new DaemonThread(), "TestDaemon" );
> (in the top most thread group) the CPE exits normally.
> However this is not possible with closed source libraries.
> Thus the threadGroupDestroyer must test for daemon threads. Furthermore the used group.activeCount() (in org.apache.uima.collection.impl.cpm.engine.CPMEngine) should only be used for information purposes - as the javadoc states - not for relying on it as a loop parameter.
--
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[jira] Commented: (UIMA-1906) Daemon thread prevents CPE exit
Posted by "Timo Boehme (JIRA)" <de...@uima.apache.org>.
[ https://issues.apache.org/jira/browse/UIMA-1906?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12923886#action_12923886 ]
Timo Boehme commented on UIMA-1906:
-----------------------------------
In one or two weeks I may get time to provide a patch for this.
> Daemon thread prevents CPE exit
> -------------------------------
>
> Key: UIMA-1906
> URL: https://issues.apache.org/jira/browse/UIMA-1906
> Project: UIMA
> Issue Type: Bug
> Components: Collection Processing
> Affects Versions: 2.3
> Reporter: Timo Boehme
>
> If a daemon thread was started within an AE and keeps running independent of the AE processing (e.g. bound to a static variable) it prevents exiting of the CPE.
> Simple test:
> add following class to a AE:
> static class DaemonThread implements Runnable {
> private static volatile Thread threadInstance;
> /** Creates a daemon thread if it not already exists. */
> public synchronized static void startThread() {
> if ( threadInstance == null ) {
> threadInstance = new Thread( new DaemonThread(), "TestDaemon" );
> threadInstance.setDaemon( true );
> threadInstance.start();
> }
> }
> @Override
> public void run() {
> while ( true ) {
> try { Thread.sleep( 2000 ); } catch ( InterruptedException ie ) {}
> }
> }
> }
> and call DaemonThread.startThread(); within the process() method.
> After CPE signals collectionProcesscomplete() the application does not exit.
> The reason: in org.apache.uima.collection.impl.cpm.engine.CPMEngine a threadGroupDestroyer thread is created (line 2522) which waits for threads to die. Since it does not check for daemon threads it counts them as normal threads to wait for and thus it waits forever (this can be seen with kill -3 PID to get a JAVA stack trace of all threads under UNIX).
> A workaround would be to put the daemon thread in another ThreadGroup. In the example if you create the tread with
> ThreadGroup parent = Thread.currentThread().getThreadGroup();
> while ( parent.getParent() != null )
> parent = parent.getParent();
> threadInstance = new Thread( parent, new DaemonThread(), "TestDaemon" );
> (in the top most thread group) the CPE exits normally.
> However this is not possible with closed source libraries.
> Thus the threadGroupDestroyer must test for daemon threads. Furthermore the used group.activeCount() (in org.apache.uima.collection.impl.cpm.engine.CPMEngine) should only be used for information purposes - as the javadoc states - not for relying on it as a loop parameter.
--
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You can reply to this email to add a comment to the issue online.