[jboss-jira] [JBoss JIRA] (JASSIST-163) RuntimeSupport.find2Methods a perf hotspot when proxy's methods are called at higher concurrency

[Nikita Tovstoles (JIRA)]

Nikita Tovstoles created JASSIST-163:
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             Summary: RuntimeSupport.find2Methods a perf hotspot when proxy's methods are called at higher concurrency
                 Key: JASSIST-163
                 URL: https://issues.jboss.org/browse/JASSIST-163
             Project: Javassist
          Issue Type: Enhancement
    Affects Versions: 3.16.1-GA, 3.15.0-GA
         Environment: hibernate-core 3.6.10.Final
            Reporter: Nikita Tovstoles
            Assignee: Shigeru Chiba


We've been profiling our Hibernate 3.6.10-based app and noticed a perf bottleneck in javassist.util.proxy.RuntimeSupport.find2methods. Unfortunately, this method, which has a synch. block, is being called on
every invocation of every proxied entity method (see javassist.util.proxy.ProxyFactory.makeForwarder(), called indirectly by
ProxyFactory.createClass()).

In our testing, the result is that our service call's latency increases from 33 to 55, 260, 400ms as concurrency increases
1-10-20-30 users on a 4-core CPU. At 20 and 30 users 51% of CPU time is spent contending for a monitor in RuntimeSupport.find2methods:
{code}
        synchronized (methods) {
            if (methods[index] == null) {
                methods[index + 1] = thisMethod == null ? null
                                     : findMethod(self, thisMethod, desc);
                methods[index] = findSuperMethod(self, superMethod, desc);
            }
        }
{code} 

Since find2methods merely interrogates class metadata, seems like its return values should be cached (in a ConcurrentMap?) instead repeatedly executing the above synchronized statement.

Full [YourKit profiler|http://yourkit.com] is attached, salient screen shots also attached separately

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