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From: "Linas Vepstas" <linasvepstas@gmail.com>
To: "Neil Jerram" <neiljerram@googlemail.com>
Cc: bug-guile@gnu.org
Subject: Re: [PATCH] Final: thread lock nesting debugging
Date: Thu, 20 Nov 2008 12:33:34 -0600	[thread overview]
Message-ID: <3ae3aa420811201033g173ffbe6r6b5b0bad6171d9c3@mail.gmail.com> (raw)
In-Reply-To: <3ae3aa420811200803u485a8fa7ia486c281da54497a@mail.gmail.com>

2008/11/20 Linas Vepstas <linasvepstas@gmail.com>:

> -- The reason for dropping the heap_mutex before grabbing
> the other lock (for example  scm_i_port_table_mutex),
> is somewhat obscure, but at one point I decided that this
> was OK, and arguably correct.  As I write this, I've
> forgotten why. However, this should be a focus of attention,
> and re-thought-out.

Well, a quick look reminds me of the situation: in many/most
cases, locked sections might trigger garbage collection.
Thus, the heap_mutex *must* be dropped before the lock
is taken.

My gut impression is that this is a poor design point; and
that the correct thing to do would be make locks fine-grained,
so that there is never a need to run GC while a lock is held.
This would require extensive auditing of the guile code.

--linas




      reply	other threads:[~2008-11-20 18:33 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-11-17  4:42 [PATCH] Final: thread lock nesting debugging Linas Vepstas
2008-11-17 13:21 ` Han-Wen Nienhuys
2008-11-18 13:26 ` Ludovic Courtès
2008-11-19 23:14 ` Neil Jerram
2008-11-19 23:21   ` Neil Jerram
2008-11-20  0:22     ` Neil Jerram
2008-11-20 16:03   ` Linas Vepstas
2008-11-20 18:33     ` Linas Vepstas [this message]

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