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From Yogesh Patel <yogesh.r.pa...@highq.com>
Subject Re: Regarding StuckThreadDetectionValve
Date Mon, 05 Oct 2015 10:28:13 GMT
Hi Thomas ,
                  Please see this image ...have a look at Time column


‚Äč

On 5 October 2015 at 14:50, Mark Thomas <markt@apache.org> wrote:

> On 05/10/2015 10:09, Yogesh Patel wrote:
> > Hi Thomas,
> >
> > Connector configuration is like :
> > <Connector port="10004" protocol="AJP/1.3" redirectPort="8443" />
>
> That means you are using the BIO AJP connector.
>
> You don't have a problem with long running requests.
>
> You have a problem with thread starvation.
>
> AJP uses persistent connections.
>
> BIO requires one thread per connection, regardless of whether or nor
> that connection is processing a request or waiting for the next one.
>
> httpd will (eventually, assuming mostly default config) create one AJP
> connection for each httpd thread. If you have more httpd threads than
> Tomcat threads you will eventually reach the point where httpd can't
> create a Tomcat thread it requires and at that point it will appear to
> hang.
>
> There are several possible fixes:
> a) disable connection re-use in httpd for AJP connections
> b) use the NIO AJP connector in Tomcat
> c) increase maxThreads in Tomcat so it is > max threads in httpd
>
> For more explanation read this:
>
> http://people.apache.org/~markt/presentations/2015-04-15-Tomcat-clustering-part-1-reverse-proxies.pdf
>
> from slide 29 to 33
>
> Mark
>
>
>
> >
> > On 5 October 2015 at 14:17, Mark Thomas <markt@apache.org> wrote:
> >
> >> On 05/10/2015 09:07, Yogesh Patel wrote:
> >>> Thanks Mark Thomas ,
> >>>
> >>>    Our application is access by Apache TO Tomcat using AJP Connector.
> >>
> >> OK. That answers one of the questions I asked. However, you haven't
> >> provided the connector configuration.
> >>
> >>>     Problem :
> >>>     Our application was mostly hanged,after looking at tomcat manager
> it
> >>> shown there are so many long running threads shown.
> >>
> >> The Tomcat Manager app does not show long running threads. It does show
> >> you how many requests are busy but again, a busy thread is not
> >> necessarily processing a request.
> >>
> >>>     We want to recognize why so many threads are running since long
> time.
> >>
> >> Threads are always "running". The key question is are those threads
> >> 'idle' or 'busy'. An idle thread is waiting to be allocated work. A busy
> >> thread has been allocated work but the manager application can't
> >> distinguish if that work is 'wait for a request to process' or
> >> 'processing a request'.
> >>
> >>>     We want to detect such thread and want to kill these stucked
> thread.
> >>
> >> You continue to make the (increasingly unlikely) assumption that 200
> >> busy threads mean you have 200 threads processing long running requests.
> >> Had you provided the connector configuration I asked for (by that I mean
> >> the <Connector ... /> elements in server.xml) then I'd be in a better
> >> position to tell you what is wrong.
> >>
> >> If you do have 200 long running requests then the
> >> StuckThreadDetectionValve is how you detect them. That fact that that
> >> valve is not reporting any long running requests should be a big clue
> >> that your assumptions about what is going on are not correct.
> >>
> >> If, and it is a big if, you did have 200 concurrent long running
> >> requests then there is no guaranteed way to stop them. If your
> >> application checks for interrupts (most don't) then the
> >> StuckThreadDetectionValve can interrupt them which should terminate the
> >> processing of that request but the time it would take to code the
> >> application to handle that properly would normally be better spent
> >> fixing the root cause of the long running request.
> >>
> >> Mark
> >>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>> On 5 October 2015 at 13:11, Mark Thomas <markt@apache.org> wrote:
> >>>
> >>>> On 05/10/2015 07:54, Yogesh Patel wrote:
> >>>>>         We are facing issues with long running thread in tomcat
. we
> >> are
> >>>>> using Tomcat-7.0.47.Tomcat manager shows Current busy threads :
200,
> >>>>> application  gets stucked due to these long running threads.
> >>>>
> >>>> What makes you think you have issues with long running threads? A busy
> >>>> thread isn't necessarily processing a request. Configuration errors
> >>>> leading to thread starvation are a more typical cause of the symptom
> you
> >>>> describe rather than long running threads in the application.
> >>>>
> >>>>>          We implemented StuckThreadDetectionValve in server.xml(
> <Valve
> >>>>>
> >>>>>     className="org.apache.catalina.valves.StuckThreadDetectionValve"
> >>>>>
> >>>>>     threshold="60" />), but it  could not help out.
> >>>>
> >>>> Why not? Again, this suggests that long running threads aren't the
> >> problem.
> >>>>
> >>>>>        So we implemented custom StuckThreadDetectionValve by
> extending
> >>>>> StuckThreadDetectionValve from
> >>>>> catalina, it only goes to "constructor","initInternal",and in
> >>>> "invoke"(when
> >>>>> action fires), it does not go to function "getStuckThreadNames()"
> even
> >>>>> after threshold time.How to achieve the same.Is there any way to
> detect
> >>>>> stucked thread and kill them?
> >>>>
> >>>> First of all your invoke() method fails to call super.invoke() so the
> >>>> Valve is never going to do anything.
> >>>>
> >>>> Secondly, if the original valve didn't work adding a bunch of
> >>>> System.out.println() lines isn't going to magically make it work.
> >>>>
> >>>> Thirdly, getStuckThreadNames() is never called by any Tomcat code so
> it
> >>>> is no surprise that you never see a call to that method. That method
> is
> >>>> intended for use via JMX.
> >>>>
> >>>> I suggest you start again and tell us more about the problem you are
> >>>> trying to solve (lack of response) and your configuration. In
> particular
> >>>> we need to know your connector configuration and how users access the
> >>>> application. Do they connect directly to Tomcat or do they go via a
> >>>> reverse proxy?
> >>>>
> >>>> Mark
> >>>>
> >>>>
> >>>>>
> >>>>>   My custom Valve is like following :
> >>>>>
> >>>>> public class StuckThreadDetection extends StuckThreadDetectionValve
> >>>>> {
> >>>>> StuckThreadDetection stuckThreadDetection;
> >>>>>
> >>>>> public StuckThreadDetection()
> >>>>> {
> >>>>> System.out.println("in StuckThreadDetection constructor");
> >>>>>
> >>>>> }
> >>>>>
> >>>>> public void invoke(Request request, Response response) throws
> >>>> IOException,
> >>>>> ServletException
> >>>>> {
> >>>>> System.out.println("in invoke...");
> >>>>>
> >>>>> getNext().invoke(request, response);
> >>>>> }
> >>>>>
> >>>>> @Override
> >>>>> protected void initInternal() throws LifecycleException
> >>>>> {
> >>>>> System.out.println("In initInternal");
> >>>>> super.initInternal();
> >>>>> }
> >>>>>
> >>>>> @Override
> >>>>> public String[] getStuckThreadNames()
> >>>>> {
> >>>>> System.out.println("in getStuckThreadNames...");
> >>>>> String[] listStuckedThread = this.getStuckThreadNames();
> >>>>>
> >>>>> for (String threadName : listStuckedThread)
> >>>>> {
> >>>>> System.out.println(threadName);
> >>>>> }
> >>>>>
> >>>>> return listStuckedThread;
> >>>>>
> >>>>> }
> >>>>>
> >>>>> @Override
> >>>>> public String getInfo()
> >>>>> {
> >>>>> System.out.println("In getInfo");
> >>>>> return super.getInfo();
> >>>>> }
> >>>>> }
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>
> >>>>
> >>>> ---------------------------------------------------------------------
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> >>>>
> >>>>
> >>>
> >>>
> >>
> >>
> >> ---------------------------------------------------------------------
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> >>
> >>
> >
> >
>
>
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>


-- 
*Thanks & Regards,*

* Yogesh Patel*

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