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Subject: Charm++ parallel programming system

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Re: [charm] Charm++ & thread in library ?


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  • From: Christian Perez <christian.perez AT inria.fr>
  • To: "Kale, Laxmikant V" <kale AT cs.uiuc.edu>
  • Cc: "charm AT cs.uiuc.edu" <charm AT cs.uiuc.edu>, "kale AT illinois.edu" <kale AT illinois.edu>
  • Subject: Re: [charm] Charm++ & thread in library ?
  • Date: Fri, 04 Jun 2010 18:09:57 +0200
  • List-archive: <http://lists.cs.uiuc.edu/pipermail/charm>
  • List-id: CHARM parallel programming system <charm.cs.uiuc.edu>
  • Organization: INRIA/LIP

I was guessing it is not an intended usage. I am going to try an hack in my code not to invoke
charm operations from those threads. It it fails, I will try another very very ugly hack but should work
to remove those pthread calls.

I'll keep you inform.

Christian

On 06/04/2010 04:16 PM, Kale, Laxmikant V wrote:
This is not an intended usage, because Charm++ likes to assume control of
cpus (and a pthread_created will relinquish that control.. charm creates
exactly the number of pthreads as the number of cores (or SMTs in some cases)
on each node.

When you create a new pthread, its going to create ambiguity about what the sending
"PE" is, for Charm++. Troubles may emanate from that. But in principle, I
think this can be supported with appropriate limitations with some work: it's a
question of whether to support such a model. (e.g. think about multiple pthreads
created in this fashion. What global variables can they access? How to ensure thread
safety in messaging layer underneath?)


--
Laxmikant Kale http://charm.cs.uiuc.edu
Professor, Computer Science
kale AT illinois.edu
201 N. Goodwin Avenue Ph: (217) 244-0094
Urbana, IL 61801-2302 FAX: (217) 265-6582


-----Original Message-----
From:
charm-bounces AT cs.uiuc.edu

[mailto:charm-bounces AT cs.uiuc.edu]
On
Behalf Of Christian Perez
Sent: Friday, June 04, 2010 7:10 AM
To:
charm AT cs.uiuc.edu
Subject: [charm] Charm++& thread in library ?

Hello,

I'd like to know whether there is a simple solution to the following
situation:
A charm application is using a library that creates threads
(pthread_create).
Those threads would like to invoke methods on charm objects.

When I test it (cf attached file), it bugs. Is it possible to support
such a situation or not?

Ugly details: the library is a JVM, but it also fails with simple example
as in the attached file.

Thank you!

Christian





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