Thread: PL/Perl crash when using threaded perl

Hi,

I was recently running both pl/perl and pl/perlu functions in a single
session, coming across the error message about failure to allocate a
second Perl interpreter on my platform. I'm running PostgreSQL 8.3.7
built from the sources on Mac OS X 10.5 with perl installed from
macports (macports were synced recently and up-to-date). I've noticed
that threads are not enabled in the macports package.

Then I've reinstalled Perl, enabling a build with threading support,
since the documentation on PL/Perl hinted me on this.
My macports package looks like this:

alexk$ port echo perl5.8 and installed
perl5.8                        @5.8.9_3+shared+threads

and the Perl flags are:

alexk$ perl -V
....
Characteristics of this binary (from libperl):
   Compile-time options: MULTIPLICITY PERL_IMPLICIT_CONTEXT
PERL_MALLOC_WRAP
                         USE_FAST_STDIO USE_ITHREADS USE_LARGE_FILES
                         USE_PERLIO USE_REENTRANT_API
   Built under darwin
   Compiled at Aug 10 2009 16:57:14
   @INC:
     /opt/local/lib/perl5/site_perl/5.8.9/darwin-thread-multi-2level
     /opt/local/lib/perl5/site_perl/5.8.9
     /opt/local/lib/perl5/site_perl
     /opt/local/lib/perl5/vendor_perl/5.8.9/darwin-thread-multi-2level
     /opt/local/lib/perl5/vendor_perl/5.8.9
     /opt/local/lib/perl5/vendor_perl
     /opt/local/lib/perl5/5.8.9/darwin-thread-multi-2level
     /opt/local/lib/perl5/5.8.9

Now PL/Perl just crashes a backend even when I try to create a
language itself.

postgres=# create language plperl;
server closed the connection unexpectedly
    This probably means the server terminated abnormally
    before or while processing the request.
The connection to the server was lost. Attempting reset: Failed.

and gdb tells me this:

Attaching to program: `/usr/local/pgsql/bin/postgres', process 9067.
Reading symbols for shared libraries ++. done
0x9403a749 in recvfrom$UNIX2003 ()
(gdb) c
Continuing.
Reading symbols for shared libraries ... done

Program received signal EXC_BAD_ACCESS, Could not access memory.
Reason: KERN_PROTECTION_FAILURE at address: 0x00000004
0x035048f5 in Perl_sv_replace ()

bt full from the running process is attached. Is there a problem with
perl built via macports (I can see both USE_ITHREADS and MULTIPLICITY,
although documentation tells about building with either of them), or
is this a bug in PL/Perl ?





Thanks,
--
Alexey Klyukin       http://www.CommandPrompt.com
The PostgreSQL Company - Command Prompt, Inc.

Alexey Klyukin wrote:
> Hi,
>
> I was recently running both pl/perl and pl/perlu functions in a single 
> session, coming across the error message about failure to allocate a 
> second Perl interpreter on my platform. I'm running PostgreSQL 8.3.7 
> built from the sources on Mac OS X 10.5 with perl installed from 
> macports (macports were synced recently and up-to-date). I've noticed 
> that threads are not enabled in the macports package.
>
> Then I've reinstalled Perl, enabling a build with threading support, 
> since the documentation on PL/Perl hinted me on this.
> My macports package looks like this:
>
> alexk$ port echo perl5.8 and installed
> perl5.8                        @5.8.9_3+shared+threads
>
> and the Perl flags are:
>
> alexk$ perl -V
> ....
> Characteristics of this binary (from libperl):
>   Compile-time options: MULTIPLICITY PERL_IMPLICIT_CONTEXT 
> PERL_MALLOC_WRAP
>                         USE_FAST_STDIO USE_ITHREADS USE_LARGE_FILES
>                         USE_PERLIO USE_REENTRANT_API
>   Built under darwin
>   Compiled at Aug 10 2009 16:57:14
>   @INC:
>     /opt/local/lib/perl5/site_perl/5.8.9/darwin-thread-multi-2level
>     /opt/local/lib/perl5/site_perl/5.8.9
>     /opt/local/lib/perl5/site_perl
>     /opt/local/lib/perl5/vendor_perl/5.8.9/darwin-thread-multi-2level
>     /opt/local/lib/perl5/vendor_perl/5.8.9
>     /opt/local/lib/perl5/vendor_perl
>     /opt/local/lib/perl5/5.8.9/darwin-thread-multi-2level
>     /opt/local/lib/perl5/5.8.9
>
> Now PL/Perl just crashes a backend even when I try to create a 
> language itself.
>
> postgres=# create language plperl;
> server closed the connection unexpectedly
>     This probably means the server terminated abnormally
>     before or while processing the request.
> The connection to the server was lost. Attempting reset: Failed.
>
> and gdb tells me this:
>
> Attaching to program: `/usr/local/pgsql/bin/postgres', process 9067.
> Reading symbols for shared libraries ++. done
> 0x9403a749 in recvfrom$UNIX2003 ()
> (gdb) c
> Continuing.
> Reading symbols for shared libraries ... done
>
> Program received signal EXC_BAD_ACCESS, Could not access memory.
> Reason: KERN_PROTECTION_FAILURE at address: 0x00000004
> 0x035048f5 in Perl_sv_replace ()
>
> bt full from the running process is attached. Is there a problem with 
> perl built via macports (I can see both USE_ITHREADS and MULTIPLICITY, 
> although documentation tells about building with either of them), or 
> is this a bug in PL/Perl ?

I wonder if this is another case of the lack of perl library 
initialisation bug we have seen before. Can you try with this patch to 
the postgres 8.3 sources? 
<http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/pl/plperl/plperl.c.diff?r1=1.136;r2=1.136.2.2>

We haven't put out an 8.3 release that includes that patch yet.

cheers

andrew

--
Alexey Klyukin   wwww.commandprompt.com
The PostgreSQL Company - Command Prompt, Inc