Hello Alan,
I currently don't have an appropriate setup here, so just the principle method
:.
Use "top - H" or htop to identify the tomcat threads with highest CPU usage.
Write down thread ids.
Create Java stack of tomcat, e. G. use jstack, kill - 3 or
jvisualvm.
Within the stack trace there is a tid which identifies the thread. Maybe you
need to convert between decimal and hex to find the right Thread.
Hope this helps,
Thomas
Von: Alan F
Gesendet: Freitag, 4. Februar 2022 13:00:29
An: Tomcat Users List
Betreff: RE: help with high cpu usage
Hello Thomas,
Thanks for your input here, what's your weapon of choice to identify this
thread bar thread dump? I just downloaded jvmtop from github but that didn't
seem to give me any clue at all about independent threads.
Cheers
Alan
-Original Message-
From: Thomas Hoffmann (Speed4Trade GmbH)
Sent: 04 February 2022 09:18
To: Tomcat Users List
Subject: AW: help with high cpu usage
Hello,
when I encounter high CPU usage, it's best to identify the thread Id which is
eating CPU.
Making a thread dump, you can then search for the thread id within this dump.
This works good for long lasting threads. If the CPU eating thread changes
quickly, it's harder to figure out.
Greetings,
Thomas
Von: Alan F
Gesendet: Freitag, 4. Februar 2022 00:02:49
An: Tomcat Users List
Betreff: Re: help with high cpu usage
John thanks so much !! Will pass this on tomorrow. Cheers.
From: john.e.gr...@wellsfargo.com.INVALID
Sent: 03 February 2022 22:45
To: users@tomcat.apache.org
Subject: RE: help with high cpu usage
Alan,
> -Original Message-
> From: Alan F
> Sent: Thursday, February 03, 2022 2:51 PM
> To: Tomcat Users List
> Subject: RE: help with high cpu usage
>
> My bad here are the correct dumps 10 secs apart
>
> https://urldefense.com/v3/__https://fastthread.io/my-thread-
> report.jsp?p=c2hhcmVkLzIwMjIvMDIvMy8tLWFwaS0zNzY2ZmZmNy0wZDgyL
> TRhZTItYmE3Mi0zMWQyYTYwN2M1ZjgudHh0&__;!!F9svGWnIaVPGSwU!-
> fDbBdZmwXsUn9QT9ftL8f4PTLoASDZOXCeB4UEo7qKgcIHhANQVT6VMoGvG
> st67ghaaLsg$
>
>
> https://urldefense.com/v3/__https://fastthread.io/my-thread-
> report.jsp?p=c2hhcmVkLzIwMjIvMDIvMy8tLWFwaS00NTE3MWUxNy1jYWRi
> LTRkY2UtODBlNS1lMDk0YTJjNTg1OGEudHh0&__;!!F9svGWnIaVPGSwU!-
> fDbBdZmwXsUn9QT9ftL8f4PTLoASDZOXCeB4UEo7qKgcIHhANQVT6VMoGvG
> st67j-3O5xU$
>
>
>
>
> -Original Message-
> From: john.e.gr...@wellsfargo.com.INVALID
>
> Sent: 03 February 2022 19:33
> To: users@tomcat.apache.org
> Subject: RE: help with high cpu usage
>
> Alan,
>
>
> > -Original Message-
> > From: Alan F
> > Sent: Thursday, February 03, 2022 12:19 PM
> > To: Tomcat Users List
> > Subject: help with high cpu usage
> >
> > Had some issues today with one prod host. One is fine the other has
> > stuck around 80%Cpu.
> > Ive taken a thread dump from both hosts and would appreciate someone
> > give a once over what it may be before I kill and restart. They are
> > clustered nodes so running identical apps and loadbalanced by a
> > hardware
> balancer.
> >
> > Node1 is ok (relatively!)
> > https://urldefense.com/v3/__https://fastthread.io/my-thread-
> >
> report.jsp?p=c2hhcmVkLzIwMjIvMDIvMy8tLWFwaS1hODllYzBkZS01OGJjLTQ
> >
> 2ZDQtYWRhNS1kYjkxZjM2NjI1ZTAudHh0&__;!!F9svGWnIaVPGSwU!91fvMc
> > RzcMYr95RrClT-eCrcDNp3fKUDpupDSNtn-mDKbTl_dmUSa0LaAolXlhipl-
> > Fk2pQ$
> >
> >
> > Node 2 still has high CPU usage
> > https://urldefense.com/v3/__https://fastthread.io/my-thread-
> >
> report.jsp?p=c2hhcmVkLzIwMjIvMDIvMy8tLWFwaS0yN2I0YWY4Mi05OWFhL
> >
> TQ3YjYtOGQ2My0wMDMwZjlkNDQzNjMudHh0&__;!!F9svGWnIaVPGSwU!9
> > 1fvMcRzcMYr95RrClT-eCrcDNp3fKUDpupDSNtn-
> > mDKbTl_dmUSa0LaAolXlhipkmLFr3E$
>
> Taking thread dumps was a good idea but I see very little activity on node 2.
> It looks like two threads are in Hibernate's
> EntityEntryContext.downgradeLocks() method, one is taking the thread
> dump itself, and another is reading a request from a client, I think.
> I would not expect this to add up to 80% CPU usage unless one of those
> threads is stuck in a loop. Comparing multiple thread dumps taken
> 5-10 seconds apart would help answer this question. How much GC is
> there? Could these Hibernate queries be pulling a huge amount of data
> from the DB, thus causing a lot of GC activity?
>
> Node 1 looks idle except for the thread taking the thread dump.
>
> Do you know for sure that it's the Tomcat process that is using the CPU?
Of the 3 dumps from the same node, the first two are 3 hours apart, yet the two
query threads seem to still be doing the s
