Re: [Q] Is it safe to create threads in Tomcat web-apps?

[Kwok Peng Tuck]

Hello Riaan, you might want to check out jcrontab.

http://jcrontab.sourceforge.net

Riaan Oberholzer wrote:

Well, that was part of my question.... if I
cannot/don't implement daemon threads to do e.g.
automatic daily tasks, what else? E.g, at the end of
the day send an e-mail to a (real life) manager with a
summary of the day's transactions.... something like
that.
Does Tomcat provide some sort of ActionEvent which you
can configure to be fired every x milliseconds?


--- Tim Funk <[EMAIL PROTECTED]> wrote:
 

You can create threads all day in tomcat, but here
are the importnatn things 
to consider:
- WHY! Are threads really the correct solution?
- If you create threads - what are their scope?
Daemon, non-daemon?
- If you create non-daemon threads - be prepared for
the consequences such as 
the JVM not going away on tomcat shutdown unless you
have taken the needed 
precautions.
- If you create dameon only threads, be prepared for
when tomcat shuts down 
and your daemon still has work to do because the JVM
could exit before your 
thread is ready to complete its unit of work
- WHY! Are threads really the correct solution?
- And last but not least: WHY! Are threads really
the correct solution?

-Tim

Riaan Oberholzer wrote:
   

I've mainly worked in BEA WebLogic before and from
colleagues and other sources I have heard it is
     

not
   

recommended (and sometimes not allowed, some even
said) to create threads in your application.
     

Indeed,
   

when the application went live in a multi-server
clustered environment, we got very inconsistent
results because of the threads, so we had to
     

remove
   

them.

Question is, how safe is it to create threads in a
Tomcat web-app? I would assume "worker" threads
     

are
   

ok, i.e. threads you create to do a specific task
     

and
   

then it terminates. When you are guaranteed the
     

thread
   

will terminate either because of an error or
     

because
   

the assigned task has been completed.

But what about "monitor" threads, i.e. threads
     

that
   

does a Thread.sleep(x) for an hour, check some
condition and goes back to sleep... some mechanism
     

you
   

implement to e.g. do a task on a
     

hourly/daily/weekly
   

base. You'd create the thread (and keep a handle
     

to
   

it) in either an InitServlet.init() and then
Thread.interrupt() in the InitServlet.destroy(),
     

or
   

you can do it in an ApplicationListener (something
like that) class which I think you can define in
     

the
   

web.xml.

How else can you implement that (monitoring) in
Tomcat?
     

   

---------------------------------------------------------------------
 

To unsubscribe, e-mail:
[EMAIL PROTECTED]
For additional commands, e-mail:
[EMAIL PROTECTED]
   



__________________________________
Do you Yahoo!?
Yahoo! SiteBuilder - Free, easy-to-use web site design software
http://sitebuilder.yahoo.com
---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]


 



---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]