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From Henri Gomez <>
Subject Re: mod_jk timeout?
Date Tue, 28 Oct 2003 09:46:55 GMT
Brian Maher a écrit :
>> On Mon, 27 Oct 2003, Henri Gomez wrote:
>>> If the thread on java side is a long running task or a blocking task,
>>> it should be handled by the servlet engine and sus some watchdog support
>>> should be added in Tomcat.
>>> In you're exemple I didn't know how the thread could be ever finished 
>>> !!!
>> In theory, that's what Thread#interrupt is for. It asks the thread to 
>> shut
>> down, resulting in setting the #interrupted flag / an 
>> InterruptedException
>> on potentially blocking calls such as wait() or sleep(). One could
>> interrupt named jsp like that.
> Actually, I was thinking the Thread#join would be better since we could 
> be in an infinite loop not doing any calls to wait() or sleep().  I was 
> thinking of implementing a scheme sort of like this:
>    mod_jk     |  tomcat
>    -----------+----------
>    PING      -->  received
>    received  <--  PONG
>       [ sleep ~2 seconds ]
>    received  <--  PING
>    PONG      -->  received
> If any side sends a PING and doesn't hear a PONG in 0.1 seconds, it can 
> assume the other side is "dead".  This would mean a there would need to 
> be a separate thread in the tomcat that is simply doing housekeeping or 
> "watch dogging" on the status of the connections.
>> However, dealing correctly with InterruptedExceptions is hard (you should
>> leave your objects in a meaningful state) and since InterruptedException
>> also is a checked exception, many people choose to
>> catch(InterruptedException ie) {}, even(?) Sun ORB code does so (not to
>> speak of my own).
> Certainly it can be hard to correctly deal with interruptions, but what 
> is the alternative.  Especially if you are running an untrusted JSP 
> pages that could contain an infinite loop.  Certainly testing for 
> infinite loops is impossible, or at least NP Complete.  And, with many 
> requests to such a web page, it would be easy to turn it into a denial 
> of service attack.
>> Those threads are inevitably lost.
> I would think that is the point.
> If I was to implement this feature, where should I look for the source 
> code, and should I simply submit a patch to be reviewed?

In the ajp13 java side and the jk side, both is jtc.

BTW, there is works on jk2 so it will have to wait a little ;(

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