Re: Threading crash using ODBC

Hiroshi Inoue wrote:

>markw wrote:
>
>
>>Here's what I have:
>>
>>I have an application with 1 main thread and a number of worker threads.
>>At startup, I allocate a number of ODBC connections.
>>I have an internal queue that is protected by a mutex.
>>When one of the worker threads wants to use the database, it gets an un
>>occupied SQL connection from the queue.
>>
>>At startup, I can execte a query just fine. When I try to execute a
>>query from one of the worker threads, I get a core dump.
>>
>>I am using UNIX ODBC and the PostgreSQL driver, as shipped with RedHat 7.3.
>>
>>The stack trace looks like this:
>>
>>0 0x402fba4c in CC_send_query () from /usr/lib/libodbcpsql.so
>>(gdb) where
>>#0 0x402fba4c in CC_send_query () from /usr/lib/libodbcpsql.so
>>#1 0x40314842 in SC_execute () from /usr/lib/libodbcpsql.so
>>#2 0x40304c45 in PG_SQLExecute () from /usr/lib/libodbcpsql.so
>>#3 0x40304c6b in SQLExecute () from /usr/lib/libodbcpsql.so
>>#4 0x402a13f4 in SQLExecute () from /usr/lib/libodbc.so.1
>>#5 0x40023d6f in MSqlODBC::ExecResult (this=0x806bfd4,
>> sql=0x4037f83c "select value, timeout from msession_sessions where
>>session = '2b7atuahma6u9igcorr7c6q8ld7ne86o'") at modbcsql.cpp:360
>>
>>
>
>It's the driver provided by unixODBC itself.
>Please inquire unixODBC team about it.
>Or try the (maybe) thread-safe driver on *nix
>recently provided at http://odbc.postgresql.org/.
>

Actually, I tracked it down. It may be something that you are interested
in, I had my stack set to 64K, when I bumped it up to 256K, the problem
went away.

Both the unixODBC and PostgreSQL drivers are similar, or at least have a
similar origin. The stack utilization deserve at least a little scrutiny.