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From "Shapira, Yoav" <Yoav.Shap...@mpi.com>
Subject RE: detecting the shutdown of tomcat in a servlet
Date Mon, 02 Aug 2004 13:22:22 GMT

Hi,

>According to your suggestion it is advisable not to use
>ServletContextListener if we are using <load on startup> feature.
>And we just need to create a separate servlet for destroying daemon
>threads.

Say what?  That's not what I said or at least not what I meant ;)  A
ServletContextListener is good.  A <load-on-startup> servlet is also
good, but for other things, as the container may restart it at will.
Using one does not preclude using the other.  For your scenario, I think
the Listener is a better choice than the servlet.

Yoav

>
>Please provide us your valuable thoughts.
>
>
>-Jignesh
>
>
>
>On Wed, 2004-07-28 at 08:57, Shapira, Yoav wrote:
>> Hi,
>> Excellent answer by Rodrigo Ruiz.  I wanted to correct one tiny part,
>> and for Tomcat it's a theoretical correction only, but since this a
>> common mistake and a blemish on an otherwise great post:
>>
>> <load-on-startup> servlets are initialized on startup by the
container.
>> But that doesn't mean they are destroyed on shutdown like the
>> ServletContextListener.  The container is free to destroy these
servlets
>> as it sees necessary, usually to preserve resources if they are not
>> under load and other servlets are.  Therefore it's entirely possible
and
>> legal for a <load-on-startup> servlet to be initialized and destroyed
>> numerous times while the webapp is NOT restarted.
>>
>> Accordingly, take his advice and use a ServletContextListener.
That's
>> what it's for ;)
>>
>> Yoav Shapira
>> Millennium Research Informatics
>>
>>
>> >-----Original Message-----
>> >From: Rodrigo Ruiz [mailto:rruiz@gridsystems.com]
>> >Sent: Wednesday, July 28, 2004 6:21 AM
>> >To: Tomcat Users List
>> >Subject: Re: detecting the shutdown of tomcat in a servlet
>> >
>> >There is more than one way :-)
>> >
>> >- From within a servlet, add a shutdown hook with
>> >Runtime.getRuntim().addShutdownHook()
>> >- Create a ServletContextListener, and implement the clean stop of
your
>> >daemon in the listener contextDestroyed() method
>> >- Create an initialization servlet, and implement the clean stop in
its
>> >destroy() method
>> >
>> >and probably a few more if you use specific Tomcat classes.
>> >
>> >I would not use the first option unless really necessary, as it
seems
>> to
>> >me a too much "low level solution".
>> >My favourite is the second option, as this is what
>> >ServletContextListeners are for. You could start and stop the thread
>> >from this listener.
>> >
>> >The second and third options will perform the thread stop when the
>> >context or the container are shut down. This includes a context stop
>> >from the admin webapp. Whether this is good or bad for your purposes
>> >depends on the actions you need to perform. I suppose you do not
want
>> >your thread to keep running if you stop the webapp, because
restarting
>> >the webapp would lead to have two daemon threads :-)
>> >
>> >HTH,
>> >Rodrigo Ruiz
>> >
>> >STOCKHOLM, Raymond wrote:
>> >
>> >>In my tomcat 4.1.30n, I have a webapp in which a deamon Thread
>> (started
>> >automatically)
>> >>is scheduled to send automatic mails every morning.
>> >>
>> >>I would like to make a clean stop of my deamon when tomcat
shutdowns.
>> >>
>> >>How can I detect that tomcat is shuting down ?
>> >>
>> >>
>> >>Raymond Stockholm
>> >>Aubay Luxembourg
>> >>51, Rue de Strasbourg
>> >>L-2561 LUXEMBOURG
>> >>Tel : +352 29 92 50 31
>> >>
>> >>
>>
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>> >>
>> >>
>> >>
>> >>
>> >
>> >
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