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From Mark Thomas <ma...@apache.org>
Subject Re: Bug that spans tomcat and tomcat-native
Date Fri, 24 Jun 2016 17:25:03 GMT
On 24/06/2016 18:11, therealneworld@gmail.com wrote:
> On Fri, Jun 24, 2016 at 11:18 AM, Mark Thomas <markt@apache.org> wrote:
>> On 24/06/2016 11:17, Rémy Maucherat wrote:
>>> 2016-06-24 12:08 GMT+02:00 Mark Thomas <markt@apache.org>:
>>>
>>>> Thanks.
>>>>
>>>> I'm going to start some local performance testing to confirm I see
>>>> similar results and, assuming I do, I'll start looking at fixing this
>>>> for 1.2.x/9.0.x and back-porting.
>>>>
>>> Hum, the fix that was submitted doesn't make sense IMO since writes can be
>>> async, so I don't see a way besides adding the "error clear" thing after
>>> each operation [and we'll remove it once OpenSSL 1.1 is there if it
>>> actually fixes it]. That's assuming this issue is real [I actually never
>>> noticed anything during my many ab runs and they use a lot of threads, so I
>>> have a hard time believing it is significant enough ;) ].
>>
>> I haven't been able to reproduce anything like this yet. So far I have
>> only been testing with tc-native 1.2.x and Tomcat 9.0.x. I might need to
>> test with 1.1.x and Tomcat 7.0.x, the versions used by the OP.
>>
>> I'm having trouble understanding how this is happening. I could imagine
>> that HashMap becoming a problem if there was a high churn in Threads.
>> I'm thinking of something like bursty traffic levels and an executor
>> aggressively halting spare threads. I need to experiment with that as well.
>>
> 
> I do not understand it either. Using the thread pool there is not much
> thread churn so I am not sure why the problem gets as bad as it does.
> I didn't look into what the hash table actually had in it. I just
> noticed that the majority of a read threads time was spent waiting for
> the lock to access this hash table. Once I added the call to
> ERR_remove_thread_state the waiting basically disappeared.
> 
> For this test the traffic is constant. Each client thread creates one
> connection and just keeps pushing requests for set number of requests,
> so we aren't even creating new connections.

Can you provide the settings you are using for the Executor as well please?

Thanks,

Mark


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