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

[Jorge C. <Jor...@ge...>]

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

__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around
http://mail.yahoo.com


-------------------------------------------------------
SF.Net email is sponsored by: Discover Easy Linux Migration Strategies
from IBM. Find simple to follow Roadmaps, straightforward articles,
informative Webcasts and more! Get everything you need to get up to
speed, fast. http://ads.osdn.com/?ad_id=7477&alloc_id=16492&op=click
_______________________________________________
Simpleweb-Support mailing list
Sim...@li...
https://lists.sourceforge.net/lists/listinfo/simpleweb-support