[PD] flext glibc double free or corruption

Thomas Grill gr at grrrr.org
Sun Nov 6 23:14:38 CET 2005

Hi Johannes,
i am trying around with pool and xsample using valgrind but the only 
violation i could provoke is on quitting PD which is unimportant (but 
shortly fixed nevertheless).

I've had a few reports concerning strange effects with flext-based 
externals (e.g. vanishing pool), and all of them have been on 
debian-unstable. When i get the chance to debug on such a machine, i'll 
research further but on my gentoo installation everything is running 
smooth at the moment.

If you could use the debug version of pool (built with "flext/build.sh 
pd gcc build-debug-single") and run pd with valgrind, some helpful 
information could probably be gathered.

many thanks,

Johannes Burström wrote:
> Hi
> after updating my debian installation (including 1ibc6) i suddenly 
> started to have problems with pool. i have narrowed it down to this: 
> closing pd after invoking [pool] in a patch, IF the xsample library is 
> loaded, makes pd crash with the following message:
> *** glibc detected *** double free or corruption (fasttop): 0x082d8ea8 ***
> Sometimes this happens when just deleting an abstraction containing 
> [pool]. I haven't been able to find a way to reproduce this, however.
> the bt of gdb shows this:
> 0x40417861 in kill () from /lib/libc.so.6
> (gdb) bt
> #0  0x40417861 in kill () from /lib/libc.so.6
> #1  0x402b4309 in pthread_kill () from /lib/libpthread.so.0
> #2  0x402b46c0 in raise () from /lib/libpthread.so.0
> #3  0x40417616 in raise () from /lib/libc.so.6
> #4  0x40418981 in abort () from /lib/libc.so.6
> #5  0x4044a960 in __fsetlocking () from /lib/libc.so.6
> #6  0x404502e9 in malloc_usable_size () from /lib/libc.so.6
> #7  0x40450d81 in free () from /lib/libc.so.6
> #8  0x4061e9d8 in flext_root_single::operator delete () from 
> /usr/local/lib/pd/extra/xsample.pd_linux
> #9  0x4061bfaf in flext_base_single::AddOutlets () from 
> /usr/local/lib/pd/extra/xsample.pd_linux
> #10 0x40419ade in exit () from /lib/libc.so.6
> #11 0x4040441b in __libc_start_main () from /lib/libc.so.6
> #12 0x08059261 in _start () at ../sysdeps/i386/elf/start.S:119
> this is on devel 0_39, checked out today, and a recent (i believe 
> yesterday) flext checkout, all compiled today.
> If related somehow, the libc6 is 2.3.5-7, from unstable, the testing 
> 2.3.5-6 had the same problem, while i didn't have this issue with 
> 2.3.2.ds1-22 (_if_ it's related - if this will continue i guess i'll try 
> to downgrade to see if it disappears).
> i'd be grateful if anyone had any clues on how to solve this.
> Johannes
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