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From Rainer Jung <>
Subject Re: JK and IIS - troubles?
Date Thu, 02 Oct 2008 00:45:10 GMT
> Rainer Jung-3 wrote:
>>> My main question here is: is it normal that that a faulty application
>>> takes
>>> down the whole site?
>> Yes, unfortunately that's a common source for trouble. If an app doesn't
>> finish processinf a request, e.g. because it wais without timeout for
>> some other service, or runs in a loop, or has a deadlock, then each
>> broken request will block a thread until finally - maybe after weeks -
>> all threads are blocked in the buggy requests of the single app.
> Again, not so common for me, nor - sorry - for what I found on the whole
> list so far.
> So, one should not think that setting a worker's connection_pool_size to x
> would limit the web server to use no more than x threads for that worker? 
> This was happening with peaks of every two hours or so, but I guess it
> depends on the site traffic.

Yes it does limit it that way. But when a timeout fires in mod_jk,
Tomcat is not aware of it and will still proceed working on the request.
Your web server though receives new rquests and forwards them, so Tomcat
could run out of memory.

Are you saying, that you can't get any content from IIS, even not
content, that does not involve Tomcat to be returned?

If so, what is your connection pool size? The default is 250, which is
quite high.

> Rainer Jung-3 wrote:
>> Beware, that the timeouts will shield IIS, but if the Tomcat can't
>> handle more requests, the timeouts in the IIS plugin will not heal Tomcat.
> Thank you for telling me. It sounds fair some way..  and it's definitely
> what is needed to take a thread dump without killing everything..  

Thread Dumps only halt the JVM for a couple of milliseconds. No need to
be afraid of them, even in serious production. Don't mix the notions of
thread dump and memory dump though. The latter takes quite long, but is
not what you need here.



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