Peter Johnson [https://community.jboss.org/people/peterj] created the discussion

"Re: JBOSS Hanging Problem"

To view the discussion, visit: https://community.jboss.org/message/803855#803855

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That could be caused by one of two problems:

a) You have one or more requests that are "hanging". When they hang, the user 
might close the browser and try again. For example, there might be an infinite 
loop in the code which from that point on consumes processing power (and 
memory, but that usually is not too significant, but that all depends on the 
app). Or there might be some other haning issue such as a database deadlock. A 
thread dump will find this. (I have had people swear that there was no such 
issue in their code, yet while the system was idle - no requests coming in - 
the CPU was running at some high percentage. A thread dump showed exactly where 
the loop was.) Eventually, all of the threads in the http request thread pool 
get used up any no-one can get on the system any more. (Just yesterday I helped 
some colleagues find such an issue in their portal code using a thread dump.)

b) You have a memory leak. Eventually the heap fills up to the point that the 
JVM has to constantly take full garbage collections. You can verify this by 
turning on one of the GC logging options (-verbose:gc should be enough to catch 
a heap problem, also us -Xloggc:xxx to log to a file). One way to find a memory 
leak is to attach JVisualVM to the process and use it to take heap snapshots 
about 10 or 15 minutes apart while the system is busy. Then have it compare the 
heap snapshots and show you the differences. That should tell you which 
object(s) have increased in numbers.
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