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From "Cohen, Laurence" <lco...@novetta.com>
Subject Re: Tomcat Application Stops Responding
Date Tue, 17 Nov 2015 18:46:51 GMT
Yep, I figured that out.  Now I'm just waiting for the app to freeze.
Unfortunately I can't email the thread dump to myself because it's on a
private network.  Well I can, but I can't move it from the private network.

On Tue, Nov 17, 2015 at 1:43 PM, Christopher Schultz <
chris@christopherschultz.net> wrote:

> Larry,
>
> On 11/17/15 10:13 AM, Cohen, Laurence wrote:
> > Chris, that's what I'm planning on doing.  But how do I get the pid since
> > it will change each time I bounce the java process?  Also, I'll have to
> > figure out how to read the thread dump.
>
> You should be able to use "ps" and "grep" to find the process id.
>
> Don't bother reading the thread dump: just email it to yourself.
>
> -chris
>
> > On Mon, Nov 16, 2015 at 5:48 PM, Christopher Schultz <
> > chris@christopherschultz.net> wrote:
> >
> >> Larry,
> >>
> >> On 11/16/15 5:08 PM, Cohen, Laurence wrote:
> >>> Thank you Christopher.  I'm going to start with the thread dump since
> we
> >>> are using jdk and that appears very straightforward.  Part of my
> dilemma
> >> is
> >>> that the problem is occurring on a private network where I do not have
> >>> access to the internet.
> >>
> >> You could have your 'wget' script trigger a jstack before bouncing
> >> Tomcat. That way, you don't have to have quick access to the server when
> >> it starts misbehaving.
> >>
> >>> Our public facing application with the same exact
> >>> build is not experiencing this problem, so I'm wondering if this is a
> >>> network issue on the private side.  I'll start here though.
> >>
> >> It's nice that it's not the other way around. It's *usually* the other
> >> way around: dev/test is juuuuust fine but prod is hosing all over the
> >> place.
> >>
> >> -chris
> >>
> >>> On Mon, Nov 16, 2015 at 4:55 PM, Christopher Schultz <
> >>> chris@christopherschultz.net> wrote:
> >>>
> >>>> Larry,
> >>>>
> >>>> On 11/16/15 4:42 PM, Cohen, Laurence wrote:
> >>>>> Are there any tools that come with Java that I can use to
> troubleshoot
> >> an
> >>>>> intermittent problem we are having?  The problem is that several
> times
> >> a
> >>>>> day, our Tomcat applications will stop responding and I'll have
to
> >>>> restart
> >>>>> them to get them working again.  It's gotten to the point where
I
> have
> >>>>> written a script which does a wget every 10 minutes against an object
> >> in
> >>>>> the DB, and if it fails, it will restart our apps.
> >>>>
> >>>> Consider using a real monitoring tool. There are some free ones
> >>>> available, such as Nagios and ighinga, that aren't much more
> complicated
> >>>> than your wget script, except that they have alerting, history, etc.
> all
> >>>> built around them. They also let you sample LOTS of things.
> >>>>
> >>>>> I've also done some statistics gathering and imported them into
a
> >>>>> spreadsheet so I can see what is going on at the time the system
is
> >>>>> crashing.  All I can see is that the Tomcat connections are spiking.
> >>>>
> >>>> Spiking to a particular limit? What does your connector configuration
> >>>> look like? And your deployment?
> >>>>
> >>>>> We are running Tomcat 7.0.59 with two apps, Postgres 9.2 on the
> backend
> >>>>> which is not administered by us, and httpd on the front end, 2.2.15.
> >> The
> >>>>> httpd server and app server are RHEL6.
> >>>>
> >>>> Just a single Tomcat instance? That narrows things down a bit. How are
> >>>> you reverse-proxying? mod_jk? mod_proxy_http?
> >>>>
> >>>> What does your JNDI DataSource configuration look like?
> >>>>
> >>>> Are you able to take a thread dump when the server seizes-up?
> >>>>
> >>>>
> >>
> http://wiki.apache.org/tomcat/HowTo#How_do_I_obtain_a_thread_dump_of_my_running_webapp_.3F
> >>>>
> >>>> This will tell you what the server is doing. I suspect you'll see a
> >>>> bunch of threads waiting on a database connection or something like
> >> that.
> >>>>
> >>>> -chris
> >>>>
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> >>>>
> >>>>
> >>>
> >>>
> >>
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> >>
> >>
> >
> >
>
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>


-- 

[image: www.novetta.com]

Larry Cohen

System Administrator


12021 Sunset Hills Road, Suite 400

Reston, VA 20190

Email  lcohen@novetta.com

Office  703-885-1064

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