Re: [Catalyst] [PATCH] [RFC] Seed the RNG in Catalyst::Engine::FastCGI
On Tuesday 03 February 2009 11:45:07 am Jonathan Rockway wrote: > * On Mon, Feb 02 2009, Andrew Rodland wrote: > > I've thought over the problem and decided that the only appropriate place > > for a fix is in Engine::FastCGI. A srand anyplace else (including the app > > code) would run either too early (not solving the "shared state" problem) > > or too late (re-seeding on every request is Bad.) > > Wait, is there a reason why we can't do this in FCGI::ProcManager > instead? This is something that affects everyone using FCGI, not just > Catalyst. > A reasonable question. I'll see if I can get gbjk's thoughts on the matter. Andrew ___ List: Catalyst@lists.scsys.co.uk Listinfo: http://lists.scsys.co.uk/cgi-bin/mailman/listinfo/catalyst Searchable archive: http://www.mail-archive.com/catalyst@lists.scsys.co.uk/ Dev site: http://dev.catalyst.perl.org/
Re: [Catalyst] [PATCH] [RFC] Seed the RNG in Catalyst::Engine::FastCGI
* On Mon, Feb 02 2009, Andrew Rodland wrote: > Due to the way FastCGI does its business, when running as an "external" > FastCGI, the perl interpreter and the Catalyst app are initialized before the > FCGI process manager does its forking. Since modern versions of Perl seed > rand() "eagerly" on startup, this leads to all of the FastCGI children > inheriting the same RNG state, and very nonrandom behavior (such as CAPTCHAs > that appear to get "stuck"). > > I've thought over the problem and decided that the only appropriate place for > a fix is in Engine::FastCGI. A srand anyplace else (including the app code) > would run either too early (not solving the "shared state" problem) or too > late (re-seeding on every request is Bad.) Wait, is there a reason why we can't do this in FCGI::ProcManager instead? This is something that affects everyone using FCGI, not just Catalyst. -- print just => another => perl => hacker => if $,=$" ___ List: Catalyst@lists.scsys.co.uk Listinfo: http://lists.scsys.co.uk/cgi-bin/mailman/listinfo/catalyst Searchable archive: http://www.mail-archive.com/catalyst@lists.scsys.co.uk/ Dev site: http://dev.catalyst.perl.org/
Re: [Catalyst] [PATCH] [RFC] Seed the RNG in Catalyst::Engine::FastCGI
On Mon, Feb 02, 2009 at 05:09:21PM -0600, Andrew Rodland wrote: > Attached is a patch that does an srand in each child immediately after > invoking pm_manage, if we are running our own process manager. applied to 5.80/trunk as r9178. -- BOFH excuse #147: Party-bug in the Aloha protocol. signature.asc Description: Digital signature ___ List: Catalyst@lists.scsys.co.uk Listinfo: http://lists.scsys.co.uk/cgi-bin/mailman/listinfo/catalyst Searchable archive: http://www.mail-archive.com/catalyst@lists.scsys.co.uk/ Dev site: http://dev.catalyst.perl.org/
[Catalyst] [PATCH] [RFC] Seed the RNG in Catalyst::Engine::FastCGI
Due to the way FastCGI does its business, when running as an "external"
FastCGI, the perl interpreter and the Catalyst app are initialized before the
FCGI process manager does its forking. Since modern versions of Perl seed
rand() "eagerly" on startup, this leads to all of the FastCGI children
inheriting the same RNG state, and very nonrandom behavior (such as CAPTCHAs
that appear to get "stuck").
I've thought over the problem and decided that the only appropriate place for
a fix is in Engine::FastCGI. A srand anyplace else (including the app code)
would run either too early (not solving the "shared state" problem) or too
late (re-seeding on every request is Bad.)
Attached is a patch that does an srand in each child immediately after
invoking pm_manage, if we are running our own process manager. I can't think
at the moment how to write a test for it, but a behavior test shows that it
completely solved the randomness problem on my end, and I ran an instrumented
version to make sure that it's not srand'ing more than once per child -- it's
not. Patch applies against Catalyst-Runtime/5.80/trunk and
Catalyst-Runtime/5.70/trunk (with negligible fuzz).
Index: lib/Catalyst/Engine/FastCGI.pm
===
--- lib/Catalyst/Engine/FastCGI.pm (revision 9173)
+++ lib/Catalyst/Engine/FastCGI.pm (working copy)
@@ -130,6 +130,8 @@
$self->daemon_detach() if $options->{detach};
$proc_manager->pm_manage();
+# Give each child its own RNG state.
+srand;
}
elsif ( $options->{detach} ) {
$self->daemon_detach();
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