Re: [Simpleweb-Support] FIX: Simple stops responding

[Andrew M. <and...@ya...>]

I wonder why the queue uses an array and not a linked list?

Niall Gallagher wrote:

>Hi Jorge,
>
>Apologies for contacting you directly. However, I
>think I have found a solution, but I don't want to be
>too hasty. What triggered this is when you said that
>at least 35 threads had to be involved. 
>
>So, I downloaded the simple-test.tar.gz and resized
>the ProcessQueue, this caused a deadlock with the very
>same test case. So if you could be so kind as to check
>to see if this works for you! In the file
>ProcessQueue.java change the following line.
>
>this.ready = new ObjectQueue(size);
>
>to 
>
>this.ready = new ObjectQueue(100);
>
>Making sure that you dont resize beyond 100. I think
>the problem is that the ProcessQueue.resize does not
>resize the ObjectQueue. This seems to work for my
>tests?
>
>Niall
>
>
>
>--- Jorge CAMPOS <Jor...@ge...> wrote:
>
>  
>
>>Hi everybody!
>>
>>From our tests with our application, it seems that
>>Simple hangs only when
>>using at least 35 threads in parallel (we're testing
>>in a 4Way Xeon with HT
>>running SuSE SLES 9.0 and JDK 1.5.0_04). From the
>>thread dump and some
>>printlns in the code it seems that one thread
>>(dequeuer) blocks because
>>there are no more requests to be processed. After
>>that everything starts
>>piling up (all the dequeuers wait for the first one
>>and the enqueuers too).
>>I know it sound a bit weird, but it could be related
>>to the locking queue
>>implementation.
>>
>>I've tried to reproduce the problem using the demo
>>server and I didn't
>>succeed. I guess the context is different (to
>>simulate some load I've put
>>one sleep and some printlns). This made me look
>>again at our thread dump...
>>and I can't see anything related to our application
>>(it seems that Simple
>>blocks within its code).
>>
>>One question Andrew: what are the specs of your
>>machine?
>>
>>I'm asking this, because I've seen some locking
>>problems in applications
>>running with HyperThreading ON.
>>
>>We will test the application running with
>>HyperThreading off and in another
>>machine to see if we can reproduce the problem.
>>
>>All your support is greatly appreciated.
>>
>>Ah, one more thing. Since in our thread dump it
>>seems all the threads are
>>still alive, I don't think this particular case
>>relates to a out of memory
>>exception (also there are no exceptions in the logs)
>>
>>
>>Jorge
>>
>>-----Original Message-----
>>From: sim...@li...
>>
>>    
>>
>[mailto:sim...@li...]On
>  
>
>>Behalf Of Niall
>>Gallagher
>>Sent: Wednesday, August 03, 2005 10:21 AM
>>To: sim...@li...
>>Subject: Re: [Simpleweb-Support] FIX: Simple stops
>>responding
>>
>>
>>Hi,
>>
>>I have taken note of the last two comments with
>>regard
>>to the server freezing! In response to the queue
>>implementation, I think that the implementation of
>>the
>>Scheduler, ObjectQueue, and ProcessQueue involved in
>>dispatching requests is fine. There are no problems
>>here.
>>
>>However, the simple.http.connect implementation may
>>be
>>at fault, and I have no doubt whatsoever that the
>>java.lang.OutOfMemory error will cause the server to
>>stop responding under very heavy load.
>>
>>I have uploaded my test framework for anyone wishing
>>to  use it to see if it will freeze their server. If
>>it does then great! let me know what happened.
>>However, I have put through well over a 100 million
>>requests using my test framework today alone and,
>>with
>>the catch(Throwable) amendments there is no
>>deadlock,
>>not even a lost thread.
>>
>>The test framework can be downloaded at
>>http://simpleweb.sf.net/simple-test.tar.gz.
>>
>>So, in conclusion, the application is thread safe
>>and
>>working properly with catch(Throwable) amendments.
>>However, the TCP related issues have not been
>>thought
>>out carefully! And I believe the simple.http.connect
>>package needs to be reworked! I will release all the
>>bug fixes as soon as I am convinced everything is
>>working.
>>
>>Thanks for the bug reports, if anyone thinks the
>>freeze is related to somthing else please let me
>>know
>>so that I can explore it!
>>
>>Niall
>>
>>
>>Niall Gallagher
>>
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>Niall Gallagher
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