[Pgpool-general] segfault in pgpool 2.2

[Tatsuo Ishii]

Thanks. I will look into this.
--
Tatsuo Ishii
SRA OSS, Inc. Japan

> Tatsuo Ishii wrote:
> >> I've run it with gdb, as you wrote. But, as before, pgpool continues to
> >> run and the segfault appears in the syslog, so I cannot run bt.
> > 
> > pgpool forks multiple child worker processes and you need to attach to
> > one of the children. Problem is, the process which you play with is
> > not known until you connect to pgpool. There are several ways to solve
> > the problem:
> > 
> > 1) take core dump. you do: ulimit -c unlimited or something like this
> >    and get segfault. You should get a coredump then see the stack
> >    trace.
> > 
> > 2) set num_init_children to 1 then you can know which child process
> >    you need to attach.
> > 
> > Please try one of them.
> > 
> > Or you could provide us self contained test case.
> 
> as I said before I cannot build a test case because the software is a
> closed source ERP.
> But, following your tips, I've reduced the processes by setting up only
> one children, so now I'm able to attach to the right process and easily
> trap the fault.
> 
> This is the fault:
> --
> Program received signal SIGSEGV, Segmentation fault.
> [Switching to Thread 0xb79746d0 (LWP 19428)]
> 0x080607d8 in is_select_query (node=0x83e95e4, sql=0x0)
>      at pool_process_query.c:2110
> 2110			while (*sql && isspace(*sql))
> --
> 
> It seems that the sql pointer parameter is null, so the while crashes
> trying to use it with *sql.
> 
> The full stack trace is:
> --
> #0  0x080607d8 in is_select_query (node=0x83e95e4, sql=0x0)
>      at pool_process_query.c:2110
> #1  0x08060780 in load_balance_enabled (backend=0x83df738, node=0x83e95e4,
>      sql=0x0) at pool_process_query.c:2081
> #2  0x0808cc9c in Execute (frontend=0x83dff78, backend=0x83df738)
>      at pool_proto_modules.c:703
> #3  0x08090107 in ProcessFrontendResponse (frontend=0x83dff78,
>      backend=0x83df738) at pool_proto_modules.c:1474
> #4  0x0805a1bb in pool_process_query (frontend=0x83dff78, 
> backend=0x83df738,
>      connection_reuse=0, first_ready_for_query_received=0)
>      at pool_process_query.c:321
> #5  0x0804f0dc in do_child (unix_fd=3, inet_fd=4) at child.c:425
> #6  0x0804be9d in fork_a_child (unix_fd=3, inet_fd=4, id=0) at main.c:828
> #7  0x0804aef0 in main (argc=2, argv=0xbffdb5f4) at main.c:434
> --
> 
> Going back seems that portal->sql_string is null.
> 
> Remind that with pgpool 2.1 all works well: I'm using it in
> production. So it must be related with a difference between the two
> versions.
> Thanks
> -- 
> Simone Tregnago