leif@crysberg.dk wrote:
> I'm using PostgreSQL in a server project that uses many
> forks and many threads in each forked process.
>
> Almost everytime I do a pthread_cancel() I get a SIGSEGV.
> I have then linked the libmudflapth into my program to catch
> the problem sooner and now that reports either 'invalid
> pointer' or 'double free or corruption' when a thread is
> cancelled. Typically I have 2 database connection opened
> before any of the threads are created. I am pretty sure that
> I'm only using 1 connection in any 1 thread, i.e. only 2 of
> the threads are doing database access and using each their
> allocated connection.
>
> After the main thread has done a pthread_cancel() I get a
> "mudflapth dump" with the following trace back (the abort
> comes from the mudflapth lib when detecting the bad pointer):
>
> #0 0xffffe405 in __kernel_vsyscall ()
> #1 0xf7ca2335 in raise () from /lib32/libc.so.6
> #2 0xf7ca3cb1 in abort () from /lib32/libc.so.6
> #3 0xf7cdb6ec in ?? () from /lib32/libc.so.6
> #4 0xf7ce71ab in free () from /lib32/libc.so.6
> #5 0xf7dec061 in free (buf=0x87ed138) at ../../../libmudflap/mf-hooks1.c:241
> #6 0xf7ef2b5c in ecpg_sqlca_key_destructor () from /lib32/libecpg.so.6
> #7 0xf7dcebb0 in __nptl_deallocate_tsd () from /lib32/libpthread.so.0
> #8 0xf7dcf509 in start_thread () from /lib32/libpthread.so.0
> #9 0xf7d5008e in clone () from /lib32/libc.so.6
>
> Looking in the ecpg_sqlca_key_destructor(), it seems to me
> that the sqlca can be deallocated several times !? (I'm not
> too much into the Postgres code including ecpg, so that is a
> novice point of view.)
>
> I have tried both pgsql-8.3.5 and pgsql-8.4rc1, with
> exactly the same result and and on many different Linux
> systems, mainly Slackware 10.2 and Ubuntu 7. I have on all
> systems configured and compiled Postgres with this configure line:
>
> ./configure --prefix=/usr/local/Packages/pgsql-8.3.5
> --with-openssl --enable-thread-safety
Could you create a small sample program that reproduces the bug?
That would make it easier for me or somebody else to do something about it.
Yours,
Laurenz Albe