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From Mark Thomas <ma...@apache.org>
Subject Re: cpu spike after upgrade from tomcat 6.0.36 to tomcat 7.0.57
Date Tue, 18 Aug 2015 17:46:48 GMT
On 18/08/2015 18:16, Christopher Schultz wrote:
> Musafir,
> 
> On 8/18/15 1:08 PM, Mark Thomas wrote:
>> On 18/08/2015 17:10, musafir wrote:
>>> On Tue, Aug 18, 2015 at 11:57 AM, Mark Thomas <markt@apache.org>
>>> wrote:
>>>
>>>> On 18/08/2015 16:50, musafir wrote:
>>>>> Hello, ugraded tomcat from 6.0.36(jdk 6) to tomcat7.0.57
>>>>> (jdk7).. os:centos 6.6 ...seeing high cpu spike after
>>>>> upgrade.... doing top and  thread dump shows  only thread
>>>>> that is always using cpu is:
>>>>
>>>> How have you matched the thread using CPU in top with the
>>>> thread in the thread dump?
>>>>
>>>> Mark
>>>>
>>>>
>>>>> "ContainerBackgroundProcessor[StandardEngine[Catalina]]"
>>>>> daemon prio=10 tid=0x00007ff8fc599800 nid=0xc1d2e waiting on
>>>>> condition [0x00007ff803ffe000] java.lang.Thread.State:
>>>>> TIMED_WAITING (sleeping) at java.lang.Thread.sleep(Native
>>>>> Method) at
>>>> org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.
> run(ContainerBase.java:1513)
>>>>>
>>>>
> at java.lang.Thread.run(Thread.java:745)
>>>>>
>>>>> disabled  backgroundProcessorDelay
>>>>> (backgroundProcessorDelay=-1) ..don't see any thread that is
>>>>> always using cpu..
>>>>>
>>>>> Q: why backgroundProcessorDelay will cause cpu spike. Is this
>>>>> disabled in tomcat6 by default? Q: will  disabling
>>>>> backgroundProcessorDelay cause any other performance issues
>>>>> with tomcat7.
>>>>>
>>>>>
>>>>> Thanks for Help!!
>>>>>
>>>>> Regards
>>>>>
>>>>
>>>> Hi Mark pid java
>>>>
>>>> top -H -p  pid for thread id   cpu eating thread
>>>>
>>>> kill -3  pid for thread dump
>>>>
>>>> and hexa nid for thread id
> 
>> Then it looks like you did something wrong because the thread you 
>> identified is sleeping. It won't be using any CPU.
> 
> Assuming that the thread has been mis-identified, could it be this?
> 
> https://bz.apache.org/bugzilla/show_bug.cgi?id=58151
> 
> That bug was filed/fixed against trunk/8.0. Any chance there is a
> similar bug in Tomcat 7?

It doesn't look like it. That bug was introduced when the non-blocking
I/O support was added in Tomcat 8. The reads in Tomcat 7 look OK.

top + lwp id + thread dump is the way to get to the bottom of this.
Something isn't right in the description above.

Mark

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