isolating thread-unsafe modules
ash+perl at best-scarper.co.uk
Mon Jul 29 07:54:27 BST 2013
> Message: 3
> Date: Sun, 28 Jul 2013 20:07:59 +0100
> From: Bob MacCallum <uncoolbob at gmail.com>
> Subject: isolating thread-unsafe modules
> To: "London.pm Perl M[ou]ngers" <london.pm at london.pm.org>
> CAFLiiKdbkM62+Wr79hyRS8h-SeR0E+QGiVj1NaHX48sTkY0Qvg at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
> Sorry for the Perl question, but I'm a bit out of my depth...
> I have a Dancer app providing a web service, and I have another script
> using the same Dancer config file and db schema (e.g. "use Dancer
> qw/:script/"). This script watches the database (for changes made by the
> web app) and does the "heavy lifting". Now I want to parallelise the heavy
> lifting with threads and it seems from the core dump and googling that
> DBD::Pg is not thread safe (see the few lines of debugger output below).
> That's fine - I am happy to run only non-database code in my "worker
> threads". The trouble is that even if I do this, I think the
> threads->create is threading the Dancer globals which include postgres
> schema connections.
> I tried a few "no My::Schema; no DBD::Pg; no Dancer ..." declarations in
> the block with the threads->create - but that didn't seem to help.
> Does anyone know how I can use thread-safe and thread-unsafe code in the
> same script? I think I just need to make a block where none of the
> Dancer/database stuff is in scope?
> I thought Thread::Isolate might help, but it hangs on the first test during
> the install. It's dated 2005.
Does anyone use 'forks'?
CPAN: "drop-in replacement for Perl threads using fork()"
It looks like it might do the trick, but I've never had cause to use it.
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