[gram-user] Re: [gram-dev] Response time anomalies during job submissions with delegation
smartin at mcs.anl.gov
Fri May 26 11:46:01 CDT 2006
Thank you very much for the investigation and analysis on this. I
created a bug entry based on your findings.
On May 26, 2006, at 8:59 AM, Peter Gardfjäll wrote:
> Apparently Java does not mandate any scheduling order for threads
> for monitor entrance. Hence, this order may vary between different JVM
> implementations and operating systems.
> In my environment, Java 1.5 queues up threads waiting for monitor
> in stack-order, which makes the implementation starvation-prone (if a
> steady stream of threads are attempting to enter the monitor, the
> waiting thread will never be granted monitor entry and will hence be
> starved out). In Java 1.4, however, threads seem to be queued in
> Consequently I restarted my container with Java 1.4 and I haven't
> (yet :)
> observed any of the abnormal response times seen previously.
> As a work-around Sun recommends the use of 'one of the excellent
> "fair" lock constructs in java.util.concurrent.'
> Maybe this approach should be taken by Globus developers in the future
> since the synchronized construct, apparently, cannot be relied upon.
> regards, Peter
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