Benjamin Rogge created FELIX-4523:
-------------------------------------
Summary: Deadlock in URLHandlers when Felix.init and Felix.stop
are called concurrently
Key: FELIX-4523
URL: https://issues.apache.org/jira/browse/FELIX-4523
Project: Felix
Issue Type: Bug
Components: Framework
Affects Versions: framework-4.2.1
Environment: linux, junittests
Reporter: Benjamin Rogge
>From time to time we are experiencing a deadlock in the URLHandlers Class in
>Apache Felix. We are using Felix as an embedded OSGi Container and instantiate
>the Felix Framework via ServiceLoader and Framework Factory ourselves. The
>situation is as follows: When Felix.stop and Felix.init are called by
>different threads, eventually
>URLHandlers.unregisterFrameworkListsForContextSearch and
>URLHandlers.registerFrameworkInstance are called by the threads. There are two
>locks: m_frameworks and the Class Object of URL (URL.class).
>registerFrameworkInstance tries to aquire m_frameworks first and via the
>constructor of URLHanders URL.class after that.
>unregisterFrameworkListsForContextSearch tries to aquire URL.class first and
>m_frameworks after that. This is a classic deadlock situation. The situation
>arises in unittests where we frequently start and stop the felix framework.
Stacktracke log:
{code}
Found one Java-level deadlock:
=============================
"FelixShutdown":
waiting to lock monitor 0x0000000000ff7710 (object 0x00000007ff33e7f0, a
java.util.ArrayList),
which is held by "main"
"main":
waiting to lock monitor 0x00000000022c4a08 (object 0x0000000783b06b18, a
java.lang.Class),
which is held by "FelixShutdown"
Java stack information for the threads listed above:
===================================================
"FelixShutdown":
at
org.apache.felix.framework.URLHandlers.unregisterFrameworkListsForContextSearch(URLHandlers.java:315)
- waiting to lock <0x00000007ff33e7f0> (a java.util.ArrayList)
- locked <0x00000007ff33e840> (a java.util.HashMap)
- locked <0x0000000783b06b18> (a java.lang.Class for java.net.URL)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at
org.apache.felix.framework.util.SecureAction.invoke(SecureAction.java:840)
at
org.apache.felix.framework.URLHandlers.unregisterFrameworkInstance(URLHandlers.java:635)
at
org.apache.felix.framework.URLHandlersActivator.stop(URLHandlersActivator.java:76)
at
org.apache.felix.framework.util.SecureAction.stopActivator(SecureAction.java:667)
at
org.apache.felix.framework.Felix$SystemBundleActivator.stop(Felix.java:4715)
at
org.apache.felix.framework.util.SecureAction.stopActivator(SecureAction.java:667)
at org.apache.felix.framework.Felix.stopBundle(Felix.java:2530)
at org.apache.felix.framework.Felix$2.run(Felix.java:959)
at java.lang.Thread.run(Thread.java:724)
"main":
at org.apache.felix.framework.URLHandlers.<init>(URLHandlers.java:150)
- waiting to lock <0x0000000783b06b18> (a java.lang.Class for
java.net.URL)
at
org.apache.felix.framework.URLHandlers.registerFrameworkInstance(URLHandlers.java:600)
- locked <0x00000007ff33e7f0> (a java.util.ArrayList)
at
org.apache.felix.framework.URLHandlersActivator.start(URLHandlersActivator.java:71)
at
org.apache.felix.framework.util.SecureAction.startActivator(SecureAction.java:645)
at
org.apache.felix.framework.Felix$SystemBundleActivator.start(Felix.java:4634)
at
org.apache.felix.framework.util.SecureAction.startActivator(SecureAction.java:645)
at org.apache.felix.framework.Felix.init(Felix.java:783)
{code}
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