Hi Jess team,
I am not sure whether the email has reached you a month ago. So I start a
second trial here and would be glad if you could take a look on this issue.
Thanks,
Ralf
p.s. ohh, I have send my first email to a single jess-user only :) So actually
this is my first trial ;)
-----Ursprüngliche Nachricht-----
Von: Grube, Ralf
Gesendet: Mittwoch, 23. März 2011 16:00
An: 'jess-u...@sandia.gov'
Betreff: Wrong results if using modules and peers in a multithreaded context
Hi,
we have seen some nondeterministic behavior if executing rules with multiple
threads on different Rete peers. Our rule base is scoped by modules which seems
to cause the problems.
Basically our execution works like this (the System.outs are there to
understand the results below):
<code>
// a Rete peer
Rete rete String threadName
String moduleName
System.out.println(String.format("<<%s, %d>> BeforeSettingModule: %s",
threadName, rete.hashCode(), moduleName));
rete.setFocus(moduleName);
rete.setCurrentModule(moduleName);
moduleName System.out.println(String.format("<<%s,
%d>> AfterSettingModule: %s", threadName, rete.hashCode(), moduleName));
// ... some more non Rete related code that consumes a litte
bit time
moduleName System.out.println(String.format("<<%s,
%d>> BeforeAddingFacts: %s", threadName, rete.hashCode(), moduleName));
for (Object fact : getFacts()) {
rete.add(fact);
}
moduleName System.out.println(String.format("<<%s,
%d>> BeforeRun: %s", threadName, rete.hashCode(), moduleName));
rete.run();
</code>
I have logged the current thread name together with the used Rete hashCode to
show:
1. each thread always works on the same Rete instance
2. each thread uses its own Rete instance
Here is an excerpt of the results:
<<pool-1-thread-13, 3779465>> BeforeSettingModule: 553486623
<<pool-1-thread-13, 3779465>> AfterSettingModule: 553486625
<<pool-1-thread-11, 7866553>> AfterSettingModule: 553486625
<<pool-1-thread-11, 7866553>> BeforeAddingFacts: 553486625
<<pool-1-thread-9, 12910198>> BeforeRun: 553486625
<<pool-1-thread-11, 7866553>> BeforeRun: 553486625
<<pool-1-thread-6, 2780950>> BeforeRun: 553486625
<<pool-1-thread-7, 11541827>> BeforeSettingModule: 553486625
<<pool-1-thread-7, 11541827>> AfterSettingModule: 553486624
<<pool-1-thread-7, 11541827>> BeforeAddingFacts: 553486624
<<pool-1-thread-15, 28571894>> BeforeSettingModule: 553486623
<<pool-1-thread-15, 28571894>> AfterSettingModule: 553486625
<<pool-1-thread-15, 28571894>> BeforeAddingFacts: 553486625
<<pool-1-thread-7, 11541827>> BeforeRun: 553486625
<<pool-1-thread-13, 3779465>> BeforeAddingFacts: 553486625
<<pool-1-thread-11, 7866553>> BeforeSettingModule: 553486625
<<pool-1-thread-11, 7866553>> AfterSettingModule: 553486626
<<pool-1-thread-11, 7866553>> BeforeAddingFacts: 553486626
<<pool-1-thread-1, 15628820>> BeforeRun: 553486625
<<pool-1-thread-13, 3779465>> BeforeRun: 553486626
The erroneous result is produced by 'pool-1-thread-13' here.
As you can see it has currentModule '553486625' before adding the facts and
before running the engine the current module suddenly is '553486626'. In this
example a suspect could be 'pool-1-thread-11' because it changes the module
just before the erroneous log. But this is not verified.
The problem causes round about 1% of our results to be wrong. The error rate
increases if increasing the number of threads.
The problem disappears if replacing the Rete peer by a separate Rete instance
that has its own rule base. So it is only related to Rete.getPeer().
Regards,
Ralf Grube
E-Mail: r.gr...@itcampus.de
Tel: +49. 341. 4 92 87 55
Fax: +49. 341. 4 92 87 01
http://www.itcampus.eu
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