On Sep 26, 2010, at 10:11 AM, Dov Rosenberg wrote:
> We have a couple of WO/EOF based applications that use project wonder
> deployed as servlets in Tomcat. One of the apps is a classic WO app that uses
> WO components and a standard WO request/response loop. Our other 2 apps
> don’t use WOComponents but do use EOF. Consequently the other 2 apps do not
> use the regular WO request/response loop.
>
> I have a couple of questions:
>
>
> 1. Looking into ERXEC it appears that when a new ERXEC is created it is
> bound into the ThreadLocal variable. If that thread makes additional calls to
> newEditingContext() it appears to always return the same ERXEC – is that
> true/by design? It doesn’t seem to get a new ERXEC.
Not true according to ERXEC.DefaultFactory._createEditingContext(...)
/**
* Actual EC creation bottleneck. Override this to return other
* subclasses.
*/
protected EOEditingContext _createEditingContext(EOObjectStore
parent) {
return new ERXEC(parent == null ?
EOEditingContext.defaultParentObjectStore() : parent);
}
> 2. When using an ERXEC in a thread we typically do something like:
>
> ERXEC ec = ERXEC.newEditingContext();
> ec.lock();
> try {
> ...
> } finally {
> ec.unlock();
> }
>
> Should we call ec.dispose() when we are done with the ec we created in
> the scope of the method? Will that prevent the ec from being reused in
> subsequent calls to the method by the same thread?
you don't have to call ec.dispose(), but you can if you want. If you do, it is
a useful practice to make ec = null; immediately after calling ec.dispose()
>
> 3. Will the built in autolocking/unlocking work correctly if the WO
> request/response loop is not used? Should we disable the autolocking
> functionality if we are not using the WO request/response loop? Are there
> other settings that should be set if we do not use autolocking?
Auto lock/unlock is turned on/off by properties. Auto lock/unlock works by
virtue of the fact that touching an ERXEC that isn't locked will cause it to be
locked and the unlocking is performed automatically at the end of the request
by the method: ERXEC.unlockAllContextsForCurrentThread(), which is called at
the end of a request by ERXApplication._endRequest()
>
> The reason I am asking these questions is that I am have some hanging issues
> in the apps that do not use the WO request/response functionality. Tracing
> the ERXEC locking behavior I can see there are cases where there are an
> UNEQUAL number of lock and unlock operations. Usually the hung threads have
> an extra lock operation. I suspect that is the root cause of my hung threads.
> It seems that the reuse of editing contexts within a thread causes the
> mismatch in the number of locks/unlocks.
For apps that don't have any requests, you can just turn off autolocking. You
can call ERXEC.unlockAllContextsForCurrentThread() yourself at the end of a
background thread task as safety net for unbalanced locks, however it is
advised to use the construct above ec.lock()/try/finally/ec.unlock() in
background threads always.
If you are familiar with java.util.concurrent, you can use
ERXExecutorService.executorService() to submit Callables and Runnable for
background execution and at the end of your task,
ERXEC.unlockAllContextsForCurrentThread() is called for automatically.
http://download.oracle.com/javase/1.5.0/docs/api/java/util/concurrent/ExecutorService.html
HTH, Kieran
>
> Thanks in advance for any insights you can provide
>
> Dov Rosenberg
>
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