DO NOT REPLY [Bug 52999] New: Performance issue with locking in ContainerBase.fireContainerEvent()

[bu...@apache.org]

https://issues.apache.org/bugzilla/show_bug.cgi?id=52999

             Bug #: 52999
           Summary: Performance issue with locking in
                    ContainerBase.fireContainerEvent()
           Product: Tomcat 7
           Version: 7.0.26
          Platform: PC
        OS/Version: Windows XP
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: Catalina
        AssignedTo: dev@tomcat.apache.org
        ReportedBy: knst.kolinko@gmail.com
    Classification: Unclassified


This was reported on dev list [1]:

> 2) org.apache.catalina.core.ContainerBase.fireContainerEvent;
> That method contains critical section:
>  synchronized (listeners) {
>        list = listeners.toArray(list);
> }
>
> Is is called pretty often with every put operation into request or
> session map. That code in tomcat looks like a candidate for
> CopyOnWriteArrayList
>

I confirm that I see fireContainerEvent() calls in many places in
StandardSession.

Moreover those are two nested loops:  a loop in StandardSession over array
of context.getApplicationEventListeners(); x copying the list of container
listeners inside into array in context.fireContainerEvent().

I cannot confirm reported problem with request attributes - I do not see
anything in the code that would send events from that access.

Is it possible to solve it with a ReadWriteLock?
Or it would be better to have a helper class that avoids copying the array over
on every access (the said copy-on-write one)?

I classify this as an enhancement request.

[1] Thread "Two performance problems (found during myfaces testing)" on dev
list, starting on 2012-03-08,
- http://tomcat.markmail.org/thread/7bbvzmkvyvryvn44
- http://marc.info/?t=133124021200002&r=1&w=2

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[Bug 52999] Performance issue with locking in ContainerBase.fireContainerEvent()

[bu...@apache.org]

https://issues.apache.org/bugzilla/show_bug.cgi?id=52999

Mark Thomas <ma...@apache.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #1 from Mark Thomas <ma...@apache.org> ---
The OP may have meant context attributes rather than request attributes.

I'm tempted to remove those container events for performance reasons.

I'm in favour of the ReadWriteLock since there is less copying and therefore
fewer objects and hence less GC.

Fixed in trunk and 7.0.x and will be included in 7.0.28 onwards.

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