https://issues.apache.org/bugzilla/show_bug.cgi?id=53450
Priority: P2
Bug ID: 53450
Assignee: dev@tomcat.apache.org
Summary: Deployment of an application with 'ROOT' context hangs
forever
Severity: normal
Classification: Unclassified
Reporter: violet...@apache.org
Hardware: PC
Status: NEW
Version: 7.0.28
Component: Catalina
Product: Tomcat 7
Hi,
The scenario is the following:
- I have running Tomcat 7.0.28
- I deploy an application with 'ROOT' context
- The deployment hangs forever. When taking a tread dump, the following is
suspicious:
"localhost-startStop-2" daemon prio=6 tid=0x0000000006607800 nid=0x2560 waiting
on condition [0x0000000009ebf000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000007d80f0108> (a
java.util.concurrent.locks.ReentrantReadWriteLock$NonfairSync)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:158)
at
java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:811)
at
java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:842)
at
java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1178)
at
java.util.concurrent.locks.ReentrantReadWriteLock$WriteLock.lock(ReentrantReadWriteLock.java:807)
at
org.apache.catalina.core.ContainerBase.removeContainerListener(ContainerBase.java:1071)
at
org.apache.catalina.core.StandardEngine$AccessLogListener.uninstall(StandardEngine.java:463)
at
org.apache.catalina.core.StandardEngine$AccessLogListener.containerEvent(StandardEngine.java:505)
at
org.apache.catalina.core.ContainerBase.fireContainerEvent(ContainerBase.java:1431)
at
org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:907)
at
org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:875)
at
org.apache.catalina.core.StandardHost.addChild(StandardHost.java:618)
at
org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1100)
at
org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:1618)
at
java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at
java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
As you can see
- A read lock is acquired at
org.apache.catalina.core.ContainerBase.fireContainerEvent(ContainerBase.java:1425)
- Then every listener is invoked to process the container event
- Then AccessLogListener is invoked
org.apache.catalina.core.StandardEngine$AccessLogListener.uninstall(StandardEngine.java:463)
- The latter causes a call for a write lock
org.apache.catalina.core.ContainerBase.removeContainerListener(ContainerBase.java:1071)
- Unfortunately in the ReentrantReadWriteLock it is stated that upgrade from
read to write lock is not possible
"Reentrancy also allows downgrading from the write lock to a read lock, by
acquiring the write lock, then the read lock and then releasing the write lock.
However, upgrading from a read lock to the write lock is not possible."
Regards
Violeta Georgieva
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