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From Filip Hanik - Dev Lists <devli...@hanik.com>
Subject Re: svn commit: r467787 - in /tomcat/tc6.0.x/trunk/java/org/apache/tomcat/util/net: NioChannel.java NioEndpoint.java SecureNioChannel.java SocketProperties.java
Date Thu, 26 Oct 2006 22:13:39 GMT
Remy Maucherat wrote:
> fhanik@apache.org wrote:
>> Author: fhanik
>> Date: Wed Oct 25 15:11:10 2006
>> New Revision: 467787
>>
>> URL: http://svn.apache.org/viewvc?view=rev&rev=467787
>> Log:
>> Documented socket properties
>> Added in the ability to cache bytebuffers based on number of channels 
>> or number of bytes
>> Added in nonGC poller events to lower CPU usage during high traffic 
>
> I'm starting to get emails again, so sorry for not replying.
>
> I am testing with the default VM settings, which basically means that 
> excessive GC will have a very visible impact. I am testing to 
> optimize, not to see which connector would be faster in the real world 
> (probably neither unless testing scalability), so I think it's 
> reasonable.
>
> This fixes the paranormal behavior I was seeing on Windows, so the NIO 
> connector works properly now. Great ! However, I still have NIO which 
> is slower than java.io which is slower than APR. It's ok if some 
> solutions are better than others on certain platforms of course.
The NIO implementation seems to be very GC intense, here are a couple of 
graphs from a profiler that shows objects that were collected during a 
test run.

http://www.hanik.com/gc-by-object-count.html
http://www.hanik.com/gc-by-object-size.html

As you can see, the majority is IO related, the rest of it, like the 
ConcurrentLinkedQueue is pretty wasteful as well, and all the HashMap 
and LinkedList are traced to calls from some java IO function. So 
naturally running our JIO connector, we get the same GC behavior.

Filip

>
> Rémy
>
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