[ruby-core:22969] Re: [Bug #744] memory leak in callcc?

Aman,

It's quite possible that the double-frees are occurring both with and
without the MBARI2 patch, but they are not causing segfaults unless MBARI2
is applied.  You may want to try using valgrind or some similar tool to
catch the double frees. (valgrind is really very good at this)

A few days ago, I pushed a branch to my github repo with the MBARI patches
applied to ruby_1_8 head.  These patches use the "thread anchors" backported
(by Nobu, I believe) from 1.9 .  It seems to be a bit slower than my
approach, but it may well be more robust.   The branch is called
ruby_1_8-mbari:

git://github.com/brentr/matzruby.git

http://github.com/brentr/matzruby/commits/ruby_1_8-mbari/

It is a dev version, but this snapshot did pass the bundled ruby test suite
and all my tests as well.
It would give you the benefits of the MBARI2 patch via the thread anchors.

I'd really be must interested in finding out whether there are still
double-frees happening.  Let me know what you find.  If the double-frees
only happen with MBARI2 applied, I'll consider replacing MBARI2 with the
thread anchors from 1.8.8-dev

- brent



Aman Gupta-6 wrote:
> 
> I can confirm that removing mbari2 fixes the issue. I was able to get
> a better stack trace, but am still unsure about the root cause and
> unable to reproduce it consistently. It seems like a double free is
> occurring for some reason and that eventually causes the segfault.
> 
> *** glibc detected *** free(): invalid pointer: 0x0000000002312734 ***
> *** glibc detected *** free(): invalid pointer: 0x0000000002312734 ***
> 
> Core was generated by `ruby gems/local/gems/god-0.7.8/bin/god'.
> Program terminated with signal 6, Aborted.
> #0  0x00007fc3d0cbb07b in raise () from /lib/libc.so.6
> (gdb) bt
> #0  0x00007fc3d0cbb07b in raise () from /lib/libc.so.6
> ...
> 
> God uses a double-fork to spawn processes, and it looks like the
> double free usually occurs when the first forked process (in
> process.rb:215) dies. God also uses a C extension
> (http://github.com/mojombo/god/blob/master/ext/god/netlink_handler.c)
> which could be causing issues across the fork.
> 
>   Aman
> 
> On Tue, Mar 10, 2009 at 8:46 PM, Brent Roman <[e-mail]> wrote:
>>
>> Aman,
>>
>> When I merge the MBARI patches with 1.8 HEAD, I also plan to replace the
>> stack optimization introduced in the MBARI2 patch with the (better)
>> thread
>> anchors already in HEAD (which, I think, were originally backported from
>> 1.9).   This should happen in the next week or so.  In the meantime, you
>> might want to try this patch against the current (MBARI 8B) patches on
>> 1.8.6
>> or 1.8.7:
>>
>> http://www.nabble.com/file/p22385077/rmMBARI2.patch
>>
>> It just disables the MBARI2 patch and leaves the rest intact.
>> It would be very helpful to find out whether or not that alone eliminates
>> God's segfaults.
>>
>> Will you give this a try?
>> If it works, I'll do an 8C patch that to replace the stack splicing of
>> MBARI2 with stack anchors on 1.8.7-p72 and perhaps 1.8.6-p287 as well.
>>
>> - brent
>>
> 
> 

-- 
View this message in context: http://www.nabble.com/-ruby-core%3A19846---Bug--744--memory-leak-in-callcc--tp20447794p22614822.html
Sent from the ruby-core mailing list archive at Nabble.com.