Re: Bug in ecpg lib ? - Mailing list pgsql-general

From Albe Laurenz
Subject Re: Bug in ecpg lib ?
Date
Msg-id D960CB61B694CF459DCFB4B0128514C202FF6684@exadv11.host.magwien.gv.at
Whole thread Raw
In response to Bug in ecpg lib ?  (leif@crysberg.dk)
List pgsql-general
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

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