Malloc: *** error for object 0x7f942ede34c0: incorrect checksum for freed object

Hi all

I’m in the process of upgrading an existing Rails app, first step is to
upgrade from ruby 1.8.7 → 1.9.2.

I’ve been able to get the app “running” with minimal changes but I’m
getting a frequent, indeterministic crashes under webrick - the app is
browsable for a short time.

I’m not sure how to investigate this much further so any pointers hugely
appreciated, I’ve tried 1.9.2-p136, p180 & p290

I’m on OSX Lion, under RVM 1.9.2 with XCode 4.1:

Rendered layouts/_footer (4.3ms)
Completed in 13104ms (View: 12781, DB: 318) | 200 OK

ruby(18257,0x10f8b1000) malloc: *** error for object 0x7f942ede34c0:
incorrect checksum for freed object - object was probably modified after
being freed.
*** set a breakpoint in malloc_error_break to debug
Abort trap: 6

$ ruby -v
ruby 1.9.2p180 (2011-02-18 revision 30909) [x86_64-darwin11.2.0]

$ gem -v

$ rvm list

rvm rubies

ruby-1.8.7-p330 [ i686 ]
ruby-1.9.2-p136 [ i386 ]
=> ruby-1.9.2-p180 [ i386 ]
ruby-1.9.2-p290 [ i386 ]

$ rvm gemset list

gemsets for ruby-1.9.2-p180
=> dis11

$ uname -a
Darwin bigapplemac.config 11.2.0 Darwin Kernel Version 11.2.0: Tue Aug
9 20:54:00 PDT 2011; root:xnu-1699.24.8~1/RELEASE_X86_64 x86_64

The output of the system crash log is attached (i hope):

I’m suspicious of natively compiled gems (all were cleanly installed
with the new ruby) but I’m not sure how to narrow that down - this is a
big, legacy project!