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From: Julia Lawall <julia.lawall@lip6.fr>
To: Markus Elfring <Markus.Elfring@web.de>
Cc: Coccinelle <cocci@systeme.lip6.fr>
Subject: Re: [Cocci] Working with pipes for parallel SmPL data processing?
Date: Mon, 10 Jun 2019 23:00:23 +0200 (CEST)
Message-ID: <alpine.DEB.2.21.1906102257030.2636@hadrien> (raw)
In-Reply-To: <4a6a6c17-5190-f2ad-d1ed-981e55fffe4f@web.de>

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On Sun, 9 Jun 2019, Markus Elfring wrote:

> Hello,
>
> The Coccinelle software supports also a variant of parallel data processing
> after the parameter “--jobs” was passed.
> https://github.com/coccinelle/coccinelle/blob/7ec31ed1fadf738bc487ccefdc63bfe0598f44cc/docs/manual/spatch_options.tex#L745
>
> It is nice when it works to distribute analysis on source files to some processors.
> Unfortunately, undesirable software behaviour can be observed if a database
> like “PostgreSQL 11.3-7.1” would be used in such a system configuration.
> Thus I imagine that it can be occasionally appropriate to perform desired
> parallel data processing by the usage of a detailed pipeline instead.
> https://ocaml.github.io/ocamlunix/pipes.html
>
> How do you think about another application for this kind of
> inter-process communication?

When you use -j, you fork processes that thus the child processes write to
a different region of memory than the parent process.

I don't have any interest in connecting Coccinelle to a database, so I'm
not going to spend any time on debugging your issue.  However, if you want
to look into it, this may be the source of the problem.

Maybe you can use a hashtable, then use merge in a finalize, and the write
the information to the database in the parent thread.

The use of merge is illustrated in eg tests/merge_vars.cocci

julia

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Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-09 17:19 Markus Elfring
2019-06-10 21:00 ` Julia Lawall [this message]
2019-06-11  7:50   ` Markus Elfring

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