cocoon-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Carsten Ziegeler" <cziege...@s-und-n.de>
Subject RE: [SHOWSTOPPER?] cocoon sources no longer thread-safe
Date Wed, 04 Dec 2002 08:03:00 GMT
Hi,

there were some problems with multi-threading and the environment
stack which should be fixed by last monday - at least that's
what I thought.

However, there is one subtle thing to keep in mind:
ThreadLocal and InheritableThreadLocal variables!
The current environment stack uses a InheritableThreadLocal
variable - so you have to make sure that if you
create/use a different thread that this InheritableThreadLocal
variable is initialized correctly.

Especially when you use thread-pools you have to
manually set this variable (contained in the
CocoonComponentManager) whenever you take a thread
out of the pool and use it.

Is it possible, that your problems are related to this?

HTH
Carsten

Carsten Ziegeler
Open Source Group, S&N AG



-----Original Message-----
From: Greg Weinger [mailto:gweinger@itmedicine.net]
Sent: Wednesday, December 04, 2002 4:23 AM
To: cocoon-dev
Subject: [SHOWSTOPPER?] cocoon sources no longer thread-safe


THE PROBLEM
----------------
In 2.0.3 and before you could execute multiple cocoon:/  uris using the
following code in a thread-safe manner:

         Source  source = resolver.resolve(src);
         source.toSAX(contentHandler);
         source.recycle();

We have an AsynchronousCIncludeTransformer that executes multiple pipelines
this way.  Multiple threads from a pool use the same SourceResolver (from
the initial request), to resolve and execute sources concurrently.

This no longer works in the current 2.0.3branch.



MORE DETAIL
--------------------
I believe that this has something to do with the Environment.  The recent
fixes to the environment stack made things much better, but there is still
some subtle issue that hasn't been resolved (so to speak).

Actually, it works correctly the first time I use our code, but Source
resolving breaks on subsequent attempts.  It seems that some subtle aspect
of the environment isn't being reset correctly.

We get this error attempting to resolve the source:
cocoon:/process?ds=demographics&id=1_1

java.lang.NullPointerException
    at
org.apache.coyote.tomcat4.CoyoteRequestFacade.getQueryString(CoyoteRequestFa
cade.java:325)
    at
org.apache.cocoon.environment.http.HttpRequest.getQueryString(HttpRequest.ja
va:178)
    at
org.apache.cocoon.environment.wrapper.RequestWrapper.<init>(RequestWrapper.j
ava:110)
    at
org.apache.cocoon.environment.wrapper.EnvironmentWrapper.<init>(EnvironmentW
rapper.java:149)
    at
org.apache.cocoon.components.source.SitemapSource.<init>(SitemapSource.java:
204)
    at
org.apache.cocoon.components.source.CocoonSourceFactory.getSource(CocoonSour
ceFactory.java:91)
    at
org.apache.cocoon.components.source.SourceHandlerImpl.getSource(SourceHandle
rImpl.java:176)
    at
org.apache.cocoon.environment.AbstractEnvironment.resolve(AbstractEnvironmen
t.java:368)
    at
dataserver.asynchronous.AsynchronousProcessorImpl.executeSource(Asynchronous
ProcessorImpl.java:414)
    at
dataserver.asynchronous.AsynchronousProcessorImpl$1.run(AsynchronousProcesso
rImpl.java:345)
    at dataserver.asynchronous.PooledThread.run(PooledThread.java:43

I've tried catching the exception in the EnvironmentWrapper, to no avail --
the Request that's passed along is no good.



MY QUESTION
-----------------------------
1) Is any of this ringing a bell?   Any clues?  Sylvain?


I know this is difficult to test without a sample.  My hope is that the
problem is significant enough to you committers to warrant fixing now.  I
would be happy to put together a test case and example for you to debug on
your own system.

Also, I would love to donate the AsynchronousCIncludeTransformer.  It's
slightly over-componentized at the moment, but I'll send it to anyone
interested.

Thanks,
Greg


---------------------------------------------------------------------
To unsubscribe, e-mail: cocoon-dev-unsubscribe@xml.apache.org
For additional commands, email: cocoon-dev-help@xml.apache.org


Mime
View raw message