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https://issues.apache.org/jira/browse/FELIX-3761?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13507152#comment-13507152
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Richard S. Hall commented on FELIX-3761:
----------------------------------------
Just to follow up with a little more detail as to why I think the lock is
necessary...
It is true that we check if the bundle is in the correct state in
BundleContextImpl.registerService(), but if we don't prevent the bundle's state
from changing then the bundle could technically be stopped in between when the
validity check occurs in BundleContextImpl and when we acquire the service
registry lock in Felix.registerService(). This is appears to be a typical
check-then-act scenario.
> When a bundle registers a service, the bundle lock is obtained without any
> real purpose
> ---------------------------------------------------------------------------------------
>
> Key: FELIX-3761
> URL: https://issues.apache.org/jira/browse/FELIX-3761
> Project: Felix
> Issue Type: Bug
> Affects Versions: framework-4.0.2
> Reporter: Guillaume Nodet
>
> It leads to the following kind of deadlocks:
> {code}
> "Felix WebConsole worker" Id=170 in WAITING on
> lock=[Ljava.lang.Object;@108a93d9
> at java.lang.Object.wait(Native Method)
> at java.lang.Object.wait(Object.java:485)
> at org.apache.felix.framework.Felix.acquireBundleLock(Felix.java:5203)
> at org.apache.felix.framework.Felix.registerService(Felix.java:3452)
> at
> org.apache.felix.framework.BundleContextImpl.registerService(BundleContextImpl.java:346)
> at
> org.apache.felix.framework.BundleContextImpl.registerService(BundleContextImpl.java:320)
> at
> org.apache.felix.webconsole.internal.core.BundlesServlet.activate(BundlesServlet.java:132)
> at
> org.apache.felix.webconsole.internal.servlet.PluginHolder$InternalPlugin.doGetConsolePlugin(PluginHolder.java:752)
> at
> org.apache.felix.webconsole.internal.servlet.PluginHolder$Plugin.getConsolePlugin(PluginHolder.java:535)
> at
> org.apache.felix.webconsole.internal.servlet.PluginHolder.getPlugin(PluginHolder.java:205)
> at
> org.apache.felix.webconsole.internal.servlet.OsgiManager.initInternalPlugins(OsgiManager.java:1016)
> at
> org.apache.felix.webconsole.internal.servlet.OsgiManager.doUpdateConfiguration(OsgiManager.java:981)
> at
> org.apache.felix.webconsole.internal.servlet.OsgiManager$6.run(OsgiManager.java:930)
> at
> org.apache.felix.webconsole.internal.servlet.Executor$Worker.run(Executor.java:67)
> "FelixFrameworkWiring" Id=168 in WAITING on lock=java.lang.Object@3d6bca49
> at java.lang.Object.wait(Native Method)
> at java.lang.Object.wait(Object.java:485)
> at
> org.apache.felix.webconsole.internal.servlet.Executor.shutdown(Executor.java:45)
> - locked org.apache.felix.webconsole.internal.servlet.Executor@21875b11
> at
> org.apache.felix.webconsole.internal.servlet.OsgiManager.dispose(OsgiManager.java:407)
> at
> org.apache.felix.webconsole.internal.KarafOsgiManagerActivator.stop(KarafOsgiManagerActivator.java:52)
> at
> org.apache.felix.framework.util.SecureAction.stopActivator(SecureAction.java:667)
> at org.apache.felix.framework.Felix.stopBundle(Felix.java:2604)
> at org.apache.felix.framework.Felix$RefreshHelper.stop(Felix.java:4961)
> at org.apache.felix.framework.Felix.refreshPackages(Felix.java:4203)
> at
> org.apache.felix.framework.FrameworkWiringImpl.run(FrameworkWiringImpl.java:172)
> at java.lang.Thread.run(Thread.java:680)
> {code}
> There's really no need to grab the bundle lock because the bundle is
> necessarily starting / active / stopping, else an exception would have been
> thrown when calling the registerService because the BundleContext object
> would have been invalidated, and the registry itself is synchronized.
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