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From "Emmanuel Lecharny (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FELIX-2434) DispatchQueue, StartLevel and PacakageAdmin threads holding VM up.
Date Tue, 10 May 2011 17:18:48 GMT

    [ https://issues.apache.org/jira/browse/FELIX-2434?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13031263#comment-13031263
] 

Emmanuel Lecharny commented on FELIX-2434:
------------------------------------------

It's a bit more complex than that :)

We don't requires our users to call felix.start(). In fact, our API is either loaded by an
OSGi capable application, and we don't start felix at all, or we detect that the user does
not use a OSGi container, and in this case, when he opens the very first connection to a LDAP
server, we then start felix (but the user does not know about it). We do that only once, as
a user may create as many connection as he wants.

Now, when the user is done with his connections, he can close them, but that does not stop
felix (who knows, he might create a new connection again, send a new LDAP requests later).

So here we are : we have to ask the user to call some strange method to stop something the
user does not even know is started, when he is done with his program. 

Here is an example of what a user can do :

  public static void main(String[] args) throws Exception
  {
    LdapNetworkConnection lc = new LdapNetworkConnection();

    lc.bind();
    lc.add( <an entry> );
    lc.close();

    System.out.println( "So long, folks..." );
  }

but he gets stuck for ever here.

This is why we would like to be able to modify the Dispatcher thread programatically through
a Felix option to make it a daemon thread.

And trust me, here, we *know* what we are doing :)

> DispatchQueue, StartLevel and PacakageAdmin threads holding VM up.
> ------------------------------------------------------------------
>
>                 Key: FELIX-2434
>                 URL: https://issues.apache.org/jira/browse/FELIX-2434
>             Project: Felix
>          Issue Type: Bug
>          Components: Framework
>    Affects Versions: framework-2.0.5
>         Environment: Linux (RHEL 4 32Bit), java 1.6 server vm (14-b08)
> Linux (RHEL 5 32bit & 64Bit) java 1.6 server vm (13)
>            Reporter: Martin Ritchie
>             Fix For: framework-4.0.0
>
>         Attachments: FELIX-EventDispatcher-setDaemon.patch
>
>
> Hi, In Qpid we started using Felix more for managing our broker plugins. However we are
having random lockups occur during our test broker shutdown.
> Our PluginManager (https://svn.apache.org/repos/asf/qpid/trunk/qpid/java/broker/src/main/java/org/apache/qpid/server/plugins/PluginManager.java)
is shutdown via a VM ShutdownHook where it closes Service Trackers and then calls stop() on
Felix followed by a waitForStop().
> We are frequently seeing the following three Felix threads in a WAITING state that could
be holding the VM up. Looking at the 2.0.5 code the EventDispatcher does not use a Daemon
thread could this be what is holding our VM open?
> Name: FelixDispatchQueue
> State: WAITING on java.util.ArrayList@dc904a
> Total blocked: 21  Total waited: 22
> Stack trace: 
> java.lang.Object.wait(Native Method)
> java.lang.Object.wait(Object.java:485)
> org.apache.felix.framework.util.EventDispatcher.run(EventDispatcher.java:917)
> org.apache.felix.framework.util.EventDispatcher.access$000(EventDispatcher.java:54)
> org.apache.felix.framework.util.EventDispatcher$1.run(EventDispatcher.java:106)
> java.lang.Thread.run(Thread.java:619)
> Name: FelixStartLevel
> State: WAITING on java.util.ArrayList@1c68b20
> Total blocked: 7  Total waited: 8
> Stack trace: 
> java.lang.Object.wait(Native Method)
> java.lang.Object.wait(Object.java:485)
> org.apache.felix.framework.StartLevelImpl.run(StartLevelImpl.java:242)
> java.lang.Thread.run(Thread.java:619)
> Name: FelixPackageAdmin
> State: WAITING on org.apache.felix.framework.PackageAdminImpl@1d4ab05
> Total blocked: 0  Total waited: 1
> Stack trace: 
> java.lang.Object.wait(Native Method)
> java.lang.Object.wait(Object.java:485)
> org.apache.felix.framework.PackageAdminImpl.run(PackageAdminImpl.java:316)
> java.lang.Thread.run(Thread.java:619)

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