Re: [Proposal] Running task asynchrously (+ patche)

[Jeanfrancois Arcand]

Ken Wood wrote:
Perhaps I missed something, but Ant already does 'almost' this same thing
by using the <parallel> capability of of Ant:
 <parallel>
    <sequential>
       <exec A ....../>
       <exec B ...../>
    </sequential>
    <exec C .... />
 </parallel>
In this construct, A and C are started at the same time, while B waits for A to 
finish before it starts.
If C needed to wait before starting (say it depends on A being up and running) 
you could do:
 <parallel>
    <sequential>
       <exec A ....../>
       <exec B ...../>
    </sequential>
    <sequential>
       <sleep X />
       <exec C .... />
    </sequential>
 </parallel>
Or, another example:
  <parallel>
    <javac A .... />
    <javac B..... />
    <javac C.... />
  </parallel>
The above starts three compilations running in parallel.
So, what I'd like to know is, what is the benefit of 'spawn' over use of 
'parallel',
besides the fact that a spawned process can remain running after Ant finishes??
Remember, while Ant is put to many uses, it's original and main purpose is to
run a build.... So, can we say a build is 'done' when Ant has finished, but has 
left
spawned processes running? What happens, for example, if one has 'spawned'
various java compilations, and then Ant finishes. Is the build done? How can
we tell? So, I think we cannot tell what is going on.... Sure, spawn may be 
great if you are using
Ant for something else, but not, I think, for builds. However, I'm interested 
in being
shown otherwise... :^)
You are right. I should RTFM. I just tried and it works fine (better 
that my solution). Rrrrr at least I've learned how ant  works.

Thanks,
-- Jeanfrancois
Dominique Devienne wrote:
 

Thanks for all the hard work Jean-Francois.
1) Could you open a new BugZilla enhancement, and attach you patch there?
This would allow to discuss you changes there, easily referenceable.
2) Why did you have to modify Task.java? It doesn't seem warranted, and
probably will not fly well with the committers.
3) Any chance you might be able to write unit tests specific to the 'spawn'
mode of <exec>?
Also, what happens of the spawned process stdin/stdout/stderr? Do you force
redirecting to a file? If I spawn a process from Ant, Ant finishes, and I
close the console, will the program stop and/or hang and/or its output will
simply be lost???
Thanks, --DD
-----Original Message-----
From: Jeanfrancois Arcand [mailto:[EMAIL PROTECTED]
Sent: Wednesday, January 22, 2003 1:29 PM
To: [EMAIL PROTECTED]
Subject: [Proposal] Running task asynchrously (+ patche)
HI,
attached is a tentative patch that allow a Task object to run
asychronously. I have tested the patch on Solaris and win2k and
everything works fine (without breaking backward compatibility).
To use the functionality, you just have to add to a task the spawn
attribute, e.g.:
<exec dir="c:/src/jakarta-tomcat-5/build/bin/" executable="sh" spawn="true">
Since some task needs a couple of seconds to start/stop, I also added a
spawnWaitUntil attribute where you can set the time required before
moving to the next Task.
I did no wrote a <spawn> task because I think the functionality should
be available to every Task. For now I did not add the functionality to
Java, Javac, Jar.
Let me know what you think. At least I have something use when <gump>ing
tomcat :-)
Thanks,
-- Jeanfrancois
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