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From Christopher Schultz <ch...@christopherschultz.net>
Subject Re: Tomcat Application Stops Responding
Date Mon, 16 Nov 2015 21:55:56 GMT
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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