[jboss-jira] [JBoss JIRA] (JASSIST-163) RuntimeSupport.find2Methods a perf hotspot when proxy's methods are called at higher concurrency
[
https://issues.jboss.org/browse/JASSIST-163?page=com.atlassian.jira.plugi...
]
Scott Marlow commented on JASSIST-163:
--------------------------------------
{quote}
My interpretation of the new code is the same as what you wrote above. But I am not sure
that the Method object contained in methods[index] is up-to-date when methods[index] is
non null. Is this guaranteed by the memory model? Since a reader thread may not
synchronize before reading methods[index], it may see that methods[index] is non null but
the Method object in methods[index] contains older values than the ones visible to the
writer thread, which sets methods[index].
{quote}
The Method object probably came from Class.getDeclaredMethods() or maybe
Class.getDeclaredMethod(). Since those calls are thread safe, the entire Method object
contents should be in main working memory.
{quote}
Count me biased, but I maintain the approach of eagerly initializing static methods[] -
submitted above is most practical:
{quote}
Would it be possible to support both lazy and eager initialization?
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: 3.15.0-GA, 3.16.1-GA
Environment: hibernate-core 3.6.10.Final
Reporter: Nikita Tovstoles
Assignee: Shigeru Chiba
Fix For: 3.17.0-GA
Attachments: blocked-threads.png, find2methods-hotspot.png,
jassist-163-fix.patch, monitor-backtraces.png, monitor-backtraces.png, Product.java,
Product_$$_javassist_0-post-patch.java, Product_$$_javassist_0.java,
Tomcat-2012-03-28(2).zip
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 of repeatedly executing the above
synchronized statement. Instead, currently, it's being called every time (?) a proxied
method is executed - see *Invocation Count* in this screen shot:
https://issues.jboss.org/secure/attachment/12353025/monitor-backtraces.png
Full [YourKit profile|http://yourkit.com] is [attached as a ZIP
archive|^Tomcat-2012-03-28(2).zip]; key screen shots from the snapshot also attached
separately
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators:
https://issues.jboss.org/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira
