From: Jacques Garrigue <garrigue@kurims.kyoto-u.ac.jp>
To: shiv@ece.ucsb.edu
Cc: caml-list@inria.fr
Subject: Re: [Caml-list] native threads not parallel?
Date: Fri, 21 Feb 2003 09:15:24 +0900 [thread overview]
Message-ID: <20030221091524C.garrigue@kurims.kyoto-u.ac.jp> (raw)
In-Reply-To: <847A10BA-4528-11D7-8C93-000393942C76@ece.ucsb.edu>
From: Shivkumar Chandrasekaran <shiv@ece.ucsb.edu>
> not. But I seem to have the same problem as discussed by Markus Mottl
> (see attachment below) on Mac OS X 10.2.4 on a dual processor G4
> machine. An earlier message in that thread mentioned that there was no
> such problem on dual-processor Linux machines.
Let's answer again, since this is a frequent question: ocaml threads
do not not support parrallelism. Only one ocaml thread will run at a
time, independently of the number of processors, and this on any
architecture/OS.
> > From :Markus Mottl < mottl@miss.wu-wien.ac.at >
> > The only thing I can imagine is that OCaml somehow changes
> > scheduling so that the threads cannot run in parallel anymore, even if
> > "enter_blocking_section" is used. Is this possible? Or am I just making
> > some stupid mistake?
enter_blocking_section only happens in C code, and is followed by a
leave_blocking_section before returning to caml code. Since the
leave_blocking_section reacquires the lock, no more than one ocaml
thread can run simultaneously.
Easy way to crash the runtime: call a caml callback immediately after
an enter_blocking_section. The two caml threads will start to
allocate simultaneously on the same heap, without any locking...
Jacques Garrigue
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next prev parent reply other threads:[~2003-02-21 0:15 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-02-20 23:10 Shivkumar Chandrasekaran
2003-02-21 0:15 ` Jacques Garrigue [this message]
2003-02-21 4:24 ` shivkumar chandrasekaran
2003-02-21 10:43 ` Markus Mottl
2003-02-21 15:11 ` Jacques Garrigue
2003-02-21 17:57 ` Markus Mottl
2003-02-24 17:39 ` Shivkumar Chandrasekaran
2003-02-21 0:32 ` Chris Uzdavinis
2003-02-21 1:56 ` james woodyatt
2003-02-21 4:43 ` shivkumar chandrasekaran
-- strict thread matches above, loose matches on Subject: below --
2001-06-15 16:49 Markus Mottl
2001-06-15 17:10 ` Xavier Leroy
2001-06-15 18:42 ` Markus Mottl
2001-06-15 21:33 ` Markus Mottl
2001-06-21 13:43 ` Markus Mottl
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