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From Christopher Schultz <>
Subject Re: Tomcat Application Stops Responding
Date Mon, 16 Nov 2015 22:48:03 GMT

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.


> On Mon, Nov 16, 2015 at 4:55 PM, Christopher Schultz <
>> 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?
>> 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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