Alex Craddock created TAP5-2799:
-----------------------------------
Summary: Thread Lockup when trying to read from a Session Object
Key: TAP5-2799
URL: https://issues.apache.org/jira/browse/TAP5-2799
Project: Tapestry 5
Issue Type: Bug
Components: tapestry-http
Affects Versions: 5.8.7
Reporter: Alex Craddock
I am not 100% sure how to recreate this but one of our servers froze up on the
443 port, when I looked into it and checked a thread dump I noticed 24 threads
all in this stack.
{code:java}
"http-nio-443-exec-25" #95 daemon prio=5 os_prio=0 cpu=6249001.07ms
elapsed=138173.76s tid=0x00007fd974035800 nid=0x6288f waiting on condition
[0x00007fd929edb000]
java.lang.Thread.State: WAITING (parking)
at jdk.internal.misc.Unsafe.park([email protected]/Native Method)
- parking to wait for <0x000000047a350910> (a
java.util.concurrent.locks.ReentrantReadWriteLock$NonfairSync)
at
java.util.concurrent.locks.LockSupport.park([email protected]/LockSupport.java:194)
at
java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt([email protected]/AbstractQueuedSynchronizer.java:885)
at
java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued([email protected]/AbstractQueuedSynchronizer.java:917)
at
java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire([email protected]/AbstractQueuedSynchronizer.java:1240)
at
java.util.concurrent.locks.ReentrantReadWriteLock$WriteLock.lock([email protected]/ReentrantReadWriteLock.java:959)
at
org.apache.tapestry5.http.internal.services.TapestrySessionFactoryImpl$SessionLockImpl.acquireWriteLock(TapestrySessionFactoryImpl.java:110)
at
org.apache.tapestry5.http.internal.services.SessionImpl.getAttribute(SessionImpl.java:50)
at
org.apache.tapestry5.http.internal.services.ClusteredSessionImpl.getAttribute(ClusteredSessionImpl.java:56)
{code}
Which seemed a bit odd to me. When I looked into the code for
"org.apache.tapestry5.http.internal.services.SessionImpl" I noticed this
{code:java}
public Object getAttribute(String name) {
this.lock.acquireWriteLock();
return this.session.getAttribute(name);
}
public List<String> getAttributeNames() {
this.lock.acquireReadLock();
return InternalUtils.toList(this.session.getAttributeNames());
}
public void setAttribute(String name, Object value) {
this.lock.acquireWriteLock();
this.session.setAttribute(name, value);
} {code}
I am not sure why, but I think it's a bug that when you are calling
getAttribute, that it should only apply a read lock rather than a write lock.
Not sure if this will solve my issue but I think this should be looked into.
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