[PD-dev] strange bug

[Roman Haefeli]

hi all

i encountered a very strange bug, that seems to be very difficult to
trace back. although i cannot provide very usuable information at this
point (i assume), i just wanted to report it anyway. as i am not a coder
and also not experienced in debugging, some of you might have hints and
ideas how to proceed. 

i can reliably crash pd, but only if a fulfill a rather funny set of
conditions. creating a [table yoyo 6e+07] pd crashes, but only:

-if i first loaded _chat.pd from netpd
-if pd is running over jack

it doesn't crash, when pd is not connected to jack while instantiating
the table. it also doesn't crash, when i first instantiate the [table]
and then load _chat.pd. 

i found out,  that it might be related to an external, that _chat.pd is
using. loading _chat.pd without the externals makes the bug
untriggerable. i haven't shrinked it down to one specific external, but
i will do so as soon as i find time. here is the list of externals, that
_chat.pd is using (only from zexy and maxlib):

netclient v0.3, written by Olaf Matthes <olaf.matthes at gmx.de>
[makesymbol] part of zexy-2.2.0 (compiled: Dec  7 2007)
        Copyright (l) 1999-2007 IOhannes m zm�nig, forum::f�::uml�te &
IEM
[list2symbol] part of zexy-2.2.0 (compiled: Dec  7 2007)
        Copyright (l) 1999-2007 IOhannes m zm�nig, forum::f�::uml�te &
IEM
[any2list] part of zexy-2.2.0 (compiled: Dec  7 2007)
        Copyright (l) 1999-2007 IOhannes m zm�nig, forum::f�::uml�te &
IEM
[symbol2list] part of zexy-2.2.0 (compiled: Dec  7 2007)
        Copyright (l) 1999-2007 IOhannes m zm�nig, forum::f�::uml�te &
IEM
[drip] part of zexy-2.2.0 (compiled: Dec  7 2007)
        Copyright (l) 1999-2007 IOhannes m zm�nig, forum::f�::uml�te &
IEM
[lister] part of zexy-2.2.0 (compiled: Dec  7 2007)
        Copyright (l) 1999-2007 IOhannes m zm�nig, forum::f�::uml�te &
IEM
[glue] part of zexy-2.2.0 (compiled: Dec  7 2007)
        Copyright (l) 1999-2007 IOhannes m zm�nig, forum::f�::uml�te &
IEM

[table yoyo 6+07] is here only used to make pd reserve a certain amount
of memory. the same happens with  a number of tables, that uses the same
amount of memory. it can also be triggered by loading heavy patches,
that cause pd to use the exact same amount of memory. the limit seems to
be somewhere around 228MB. 

i tested it on two computers:

pd-0.40.3 / ubuntu dapper / pentium M / 512MB RAM
pd-0.40.3 / ubuntu gutsy / amd (can't recall exact model) / 1.5GB RAM

and on both i encountered the exact same behaviour. however, someone
from #dataflow tried to trigger it as well and failed. actually i don't
even know, if it is worth investigating it, since i found a way to use
more memory with pd than 228MB.

comments appreciated.

roman



here the output of:

valgrind pd -rt -stderr -jack -channels 6 -open /home/roman/netpd/_chat.pd

(after instantiating  [table yoyo 6e+07]), if this could be of any help:

pd: resizebytes() failed -- out of memory
==11536== 
==11536== Thread 1:
==11536== Invalid write of size 4
==11536==    at 0x8078C74: word_init (g_scalar.c:27)
==11536==  Address 0x4 is not stack'd, malloc'd or (recently) free'd
==11536== 
==11536== Process terminating with default action of signal 11 (SIGSEGV)
==11536==  Access not within mapped region at address 0x4
==11536==    at 0x8078C74: word_init (g_scalar.c:27)
==11536== 
==11536== ERROR SUMMARY: 150 errors from 27 contexts (suppressed: 23
from 1)
==11536== malloc/free: in use at exit: 332,958 bytes in 11,950 blocks.
==11536== malloc/free: 19,862 allocs, 7,912 frees, 242,700,919 bytes
allocated.
==11536== For counts of detected errors, rerun with: -v
==11536== searching for pointers to 11,950 not-freed blocks.
==11536== checked 18,409,376 bytes.
==11536== 
==11536== LEAK SUMMARY:
==11536==    definitely lost: 4,149 bytes in 59 blocks.
==11536==      possibly lost: 136 bytes in 2 blocks.
==11536==    still reachable: 328,673 bytes in 11,889 blocks.
==11536==         suppressed: 0 bytes in 0 blocks.
==11536== Use --leak-check=full to see details of leaked memory.
Killed
pd_gui: pd process exited




		
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