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From Mark Thomas <ma...@apache.org>
Subject Re: tomcat thread incurring CPU load
Date Mon, 18 Nov 2019 19:28:27 GMT
On 18/11/2019 14:14, Mark Thomas wrote:
> On 18/11/2019 12:06, M. Manna wrote:
>> Mark and others,
>>
>> On Mon, 18 Nov 2019 at 12:01, Mark Thomas <markt@apache.org> wrote:
>>
>>> OK, it looks like I can reproduce this.
>>>
>>> Steps to reproduce:
>>>
>>> - Windows 2016 Server fully patched
>>> - Java 1.8.0u144
>>> - Install Tomcat 8.5.45 from windows installer
>>> - Add tcnative-1.dll (64-bit) from Tomcat Native 1.2.23
>>> - Modify server.xml to use Http11AprProtocol on port 8080
>>> - Make a single request
>>>
>>> I then see 1 core running at 100% until the connection times out after
>>> 20s. Make another request and a core goes back up to 100% for 20s (the
>>> default keep-alive time out).
>>>
>>
>>  I have also successfully reproduced this with making a single request
>> (sorry for not replying in the weekend). Not sure how your graph looked
>> like, but the Jvisualvm showed me a Sinusoidal modulation curve as soon as
>> the request hit the server. and it didn't go down at all.
> 
> I see similar behaviour on Windows 7 but the the CPU usage drops after ~5s.
> 
> A binary search indicates that the issue was introduced with this commit:
> 
> https://github.com/apache/tomcat/commit/fffb08790e642e03f00c5f96a3a61ee09a2c8342
> 
> (this is for 9.0.x - 8.5.x and 7.0.x had similar commits)
> 
> However, that code was removed when APR was switched to a single poll
> set.

Ah ha. It was removed in 9.0.x but not in 8.5.x (only 9.0.x switched to
a single Poller) so it does look like this change is responsible.

Mark

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