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From Jerry Lampi <...@sdsusa.com>
Subject Re: Enabling protocol="org.apache.coyote.http11.Http11NioProtocol" causes tomcat 6.0.36 to load web page elements
Date Wed, 17 Jul 2013 21:39:02 GMT
On 7/17/2013 2:57 PM, Christopher Schultz wrote:
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> Jerry,
>
> On 7/17/13 3:30 PM, Jerry Lampi wrote:
>> On 7/17/2013 2:28 PM, Christopher Schultz wrote: Jerry,
>>
>> On 7/17/13 3:06 PM, Jerry Lampi wrote:
>>>>> Good news.  I previously reported that sendFile was not
>>>>> enabled.
>>>>>
>>>>> As stated below by folks more knowledgeable than I, sendFile
>>>>> is enabled by default.
>>>>>
>>>>> I added this line to my server.xml file Connector:
>>>>> useSendfile="false" and now every page element loads very
>>>>> quickly. Problem solved.
>> That's kind of what I was hoping. Honestly, sendFile *should* be
>> enabled as it should be more efficient, but something is obviously
>> going wrong.
>>
>>>>> So it appears that sendFile became broken (at least in my
>>>>> USS implementation) in version 6.0.36 and beyond.
>>>>>
>>>>> Should I open an issue for this?  In 6.0.35, sendFile seemed
>>>>> fine, in 6.0.36 and beyond (including 7.x), it is not fine.
>> Are you always using the same JVM version when testing these
>> against one another?
>>> Yes.  Same JVM. I had another idea.  I wonder if tomcat 6.0.35
>>> and below were never REALLY asking for sendFile?  That would mean
>>> that the sendFile implementation on the IBM USS mainframe is
>>> faulty, but was not being exercised by tomcat until 6.0.36 and
>>> beyond.  I find that possible, as we have had to debug other
>>> issues on that platform.
> The only related issue I see in the changelog for 6.0.36 is:
>
> https://issues.apache.org/bugzilla/show_bug.cgi?id=52858
Following 52858 led me to 
https://issues.apache.org/bugzilla/show_bug.cgi?id=53138.
It appears that this exact change: 
http://svn.apache.org/viewvc/tomcat/tc6.0.x/trunk/java/org/apache/tomcat/util/net/NioEndpoint.java?r1=1372035&r2=1372034&pathrev=1372035

re-activated sendFile on 6.0.36.  This seems to have caused slow 
(inefficient) code to be run on the IBM USS Mainframe. Specifically, the 
line that was commented out:

//unreg(sk,attachment);//only do this if we do process send file on a separate thread
Now is not:
unreg(sk, attachment, sk.readyOps());

So this issue's description may be summarized better as "The 
implementation of sendFile on the IBM USS Mainframe JVM is slow and 
inefficient".

I am pretty happy with that answer.

Jerry
>
> Since the file-fetches seem to take a really long time, would you be
> able to get a few thread dumps during those times? It might point to
> what operation is stalling.
>
> - -chris
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> =nyis
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