[Mono-osx] Massive(!) ReaderWriterLock bottleneck

[Rodrigo Kumpera]

Mono's RWLock uses CLR monitors, so it's not trivial to improve over it.


On Thu, Sep 24, 2009 at 1:19 PM, LKeene <lionel.keene at gmail.com> wrote:

>
> Hello fellow Mono+Mac coders.
>
> I've had a couple of posts in the MacOS section of the Mono forum inquiring
> about any known bottlenecks in Mono on OSX. This was due to some strange
> behavior my WinForms app was delivering when running on Mac, whereas on
> Windows and Linux all was well. I've finally tracked down the source and it
> seems to be Mono's implementation of the ReaderWriterLock class. I'm using
> an asynchronous strategy to read/process binary files...essentially I have
> one thread reading chunks from the disk and then passing it off to a
> cluster
> of worker threads that process the data. While the worker threads process
> the data, the read thread goes ahead and reads the next chunk, etc. I use
> the ReaderWriterLock to synchronize the operation.
>
> This method is working very well on Windows and Linux i.e. I am able to
> completely hide the processing time "inside" the latency of the read
> operation on my Core i7. To process my entire binary test file takes
> approx.
> 0.4 seconds on Win/Linux. The problem arises when running the same app on
> Mac. The time goes from 0.4 sec to 12+ seconds. After looking everywhere
> else for the bottleneck, out of desperation I dropped the number of worker
> threads to 1 (now using 1 read thread and 1 worker thread, same
> synchronization). The execution time on Win/Linux remains very similar
> (around 0.4 secs) but the execution time on Mac drops from 12 secs to 0.5
> secs. Increasing the number of worker threads to 7 bumps up the execution
> time to 12+ seconds again.
>
> I don't know what is causing this, but for now I would recommend anyone
> trying to use the ReaderWriterLock class to consider "rolling their own"
> via
> synchronization primitives.
>
> Anyone else see this behavior?
>
> -L
> --
> View this message in context:
> http://www.nabble.com/Massive%28%21%29-ReaderWriterLock-bottleneck-tp25577788p25577788.html
> Sent from the Mono - OSX mailing list archive at Nabble.com.
>
> _______________________________________________
> Mono-osx mailing list
> Mono-osx at lists.ximian.com
> http://lists.ximian.com/mailman/listinfo/mono-osx
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.ximian.com/pipermail/mono-osx/attachments/20091017/716c4a76/attachment.html