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sybperl-l Archive
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From: Jonathan Swartz <swartz at pobox dot com>
Subject: Re: strange bug with DBD::Sybase and mod_perl
Date: Jan 7 2010 6:29PM
Ok, take sendmail out of the equation. The bug will occur iff the
subprocess sends output to STDOUT.
Here's a slightly simplified version.
our ($dbh1, $dbh2);
sub dbconnect {
return DBI->connect( 'DBI:Sybase:...', '...', '...',
{ RaiseError => 1 } );
}
sub testdb {
my ( $name, $dbh ) = @_;
eval { $dbh->do("select 1") };
print "$name - " . ($@ ? "error: $@" : "ok") . "\n";
}
sub handler {
my ($r) = @_;
# connect.pl contains one line: BEGIN { $Handler::dbh1 =
Handler::dbconnect() }
do "/home/jswartz/projects/unchained-transaction/connect.pl";
$dbh2 = dbconnect();
system(qq{perl -e 'print "hi"'});
testdb("dbh1", $dbh1);
testdb("dbh2", $dbh2);
return 0;
}
This outputs
dbh1 - ok
dbh2 - error: DBD::Sybase::db do failed: OpenClient message: LAYER
= (5) ORIGIN = (3) SEVERITY = (5) NUMBER = (6)
Server SANDBOX5, database
Message String: ct_results(): network packet layer: internal net
library error: Net-Library operation terminated due to disconnect
OpenClient message: LAYER = (1) ORIGIN = (1) SEVERITY = (1) NUMBER
= (50)
Server SANDBOX5, database
Message String: ct_cmd_drop(): user api layer: external error: The
connection has been marked dead.
However, if I replace the system with
system(qq{perl -e ''});
or
system(qq{perl -e 'print "hi"' > /dev/null});
then it outputs
dbh1 - ok
dbh2 - ok
On Jan 6, 2010, at 1:20 PM, Jonathan Swartz wrote:
> This is a very bizarre bug occurring with DBD::Sybase, sendmail and
> mod_perl. I've minimized it as much as I can. Please bear with me. :)
>
> Here is my mod_perl handler:
>
> package Handler;
> use DBI;
> use strict;
> use warnings;
>
> our ($dbh1, $dbh2);
>
> sub dbconnect {
> return DBI->connect( 'DBI:Sybase:...', '...', '...',
> { RaiseError => 1 } );
> }
>
> sub testdb {
> my ( $name, $dbh ) = @_;
> eval { $dbh->do("select 1") };
> print "$name - " . ($@ ? "error: $@" : "ok") . "\n";
> }
>
> sub handler {
> my ($r) = @_;
>
> # connect.pl contains one line: BEGIN { $Handler::dbh1 =
> Handler::dbconnect() }
> do "/home/jswartz/projects/unchained-transaction/connect.pl";
> $dbh2 = dbconnect();
>
> open( MAIL, "|/usr/sbin/sendmail" ) || die "Can't open";
> testdb("dbh1", $dbh1);
> testdb("dbh2", $dbh2);
> close(MAIL);
> testdb("dbh1", $dbh1);
> testdb("dbh2", $dbh2);
>
> return 0;
> }
>
> 1;
>
> When I hit / on this server, it outputs:
>
> dbh1 - ok
> dbh2 - ok
> dbh1 - ok
> dbh2 - error: DBD::Sybase::db do failed: OpenClient message: LAYER
> = (5) ORIGIN = (3) SEVERITY = (5) NUMBER = (6)
> Server SANDBOX5, database
> Message String: ct_results(): network packet layer: internal net
> library error: Net-Library operation terminated due to disconnect
> OpenClient message: LAYER = (1) ORIGIN = (1) SEVERITY = (1) NUMBER
> = (50)
> Server SANDBOX5, database
> Message String: ct_cmd_drop(): user api layer: external error: The
> connection has been marked dead.
>
> That is, $dbh2 goes "bad" when the pipe to sendmail is closed. (?!)
> Note that ping() still returns 1, I have to call do() to get the
> error.
>
> Just about everything here is necessary to generate the bug. In
> particular, I cannot generate the bug...
> * If I move the code from connect.pl into the handler, even as a
> string eval
> * If I remove the "BEGIN" from connect.pl
> * If I replace sendmail with another program
> * If I run this in a script outside of mod_perl - even a script that
> forks
>
> Obviously, I can change around our current code base to not hit this
> particular condition, but that gives me no confidence that it won't
> accidentally arise again, in this or another form.
>
> Any advice on how to proceed appreciated!
>
> Thanks
> Jon
>
> --------------
> Using perl 5.10.1, DBI 1.609 , DBD::Sybase 1.09, Apache 2.2.14
> (latest versions of all).
>
> httpd.conf contains:
>
> LoadModule perl_module /home/mercury/vendor/httpd/modules/mod_perl.so
>
> ServerRoot /home/jswartz/projects/unchained-transaction
> DocumentRoot /home/jswartz/projects/unchained-transaction/htdocs
> PidFile logs/httpd.pid
> TypesConfig conf/mime.types
>
> MinSpareServers 2
> MaxSpareServers 3
> StartServers 2
> MaxClients 4
> MaxRequestsPerChild 100
>
> PerlPostConfigRequire /home/jswartz/projects/unchained-transaction/
> conf/startup.pl
> Listen 3010
>
> SetHandler perl-script
> PerlHandler Handler
>
>
> Summary of my perl5 (revision 5 version 10 subversion 1)
> configuration:
>
> Platform:
> osname=linux, osvers=2.6.18-53.el5, archname=i686-linux
> uname='linux hp-lt-171-rnebel.ensenda.com 2.6.18-53.el5 #1 smp wed
> oct 10 16:34:02 edt 2007 i686 i686 i386 gnulinux '
> config_args='-des -Uusethreads -Dprefix=/home/mercury/vendor/perl'
> hint=recommended, useposix=true, d_sigaction=define
> useithreads=undef, usemultiplicity=undef
> useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
> use64bitint=undef, use64bitall=undef, uselongdouble=undef
> usemymalloc=n, bincompat5005=undef
> Compiler:
> cc='cc', ccflags ='-fno-strict-aliasing -pipe -fstack-protector -I/
> usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_B\
> ITS=64',
> optimize='-O2',
> cppflags='-fno-strict-aliasing -pipe -fstack-protector -I/usr/
> local/include'
> ccversion='', gccversion='4.1.2 20070626 (Red Hat 4.1.2-14)',
> gccosandvers=''
> intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
> d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
> ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t',
> lseeksize=8
> alignbytes=4, prototype=define
> Linker and Libraries:
> ld='cc', ldflags =' -fstack-protector -L/usr/local/lib'
> libpth=/usr/local/lib /lib /usr/lib
> libs=-lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lc
> perllibs=-lnsl -ldl -lm -lcrypt -lutil -lc
> libc=/lib/libc-2.5.so, so=so, useshrplib=false, libperl=libperl.a
> gnulibc_version='2.5'
> Dynamic Linking:
> dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
> cccdlflags='-fPIC', lddlflags='-shared -O2 -L/usr/local/lib -
> fstack-protector'
>
>
> Characteristics of this binary (from libperl):
> Compile-time options: PERL_DONT_CREATE_GVSV PERL_MALLOC_WRAP
> USE_LARGE_FILES USE_PERLIO
> Built under linux
> Compiled at Nov 20 2009 15:56:22
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