Re: bug in DBD::MySQL on Ubuntu / Sarge

Hi,

The problem does indeed look like a Perl problem. 

I have done a number of experiments, most notably adding Perl_sv_dump()
into the loop around the param array in parse_params.   This indicated
that the FLAGS in the SV structure change between successive calls. 

I can demonstrate this without even using DBD::MySQL:

#! /usr/bin/perl5 -w

use strict;
use Devel::Peek;

my $v = '4000930012345671';

print "=" x 20, "Call 1", "=" x 20, "\n";
cancel( $v );  # pPOK flag is set
print "=" x 20, "Call 2", "=" x 20, "\n";
cancel( $v );  # bug - pPOK flag is not set

sub cancel {
  my ( $dcref ) = @_;
  Dump( substr( $dcref, -11 ) );
}

  

On perl 5.8.4:  we get:

====================Call 1====================
SV = PVLV(0x81635e0) at 0x816addc
  REFCNT = 1
  FLAGS = (PADMY,GMG,SMG,pPOK)
  IV = 0
  NV = 0
  PV = 0x8165ae8 "30012345671"\0
  CUR = 11
  LEN = 12
  MAGIC = 0x8165e40
    MG_VIRTUAL = &PL_vtbl_substr
    MG_TYPE = PERL_MAGIC_substr(x)
  TYPE = x
  TARGOFF = 5
  TARGLEN = 11
  TARG = 0x816ad88
  SV = PV(0x814cf38) at 0x816ad88
    REFCNT = 2
    FLAGS = (PADBUSY,PADMY,POK,pPOK)
    PV = 0x816bb50 "4000930012345671"\0
    CUR = 16
    LEN = 17
====================Call 2====================
SV = PVLV(0x81635e0) at 0x816addc
  REFCNT = 1
  FLAGS = (PADMY,GMG,SMG)
  IV = 0
  NV = 0
  PV = 0x8165ae8 "30012345671"\0
  CUR = 11
  LEN = 12
  MAGIC = 0x8165e40
    MG_VIRTUAL = &PL_vtbl_substr
    MG_TYPE = PERL_MAGIC_substr(x)
  TYPE = x
  TARGOFF = 5
  TARGLEN = 11
  TARG = 0x814cbb8
  SV = PV(0x814d0f4) at 0x814cbb8
    REFCNT = 2
    FLAGS = (PADBUSY,PADMY,POK,pPOK)
    PV = 0x8165d50 "4000930012345671"\0
    CUR = 16
    LEN = 17



In Call 1, FLAGS includes pPOK, but in call 2, this is missing.

In dbdimp.c, parse_params traverses the param list, and if
SvOK(ph->value) is not set, then the parameter is set to NULL.   I'm
assuming that SvOK() returns true for Call 1 and false for Call 2.

In Perl 5.6.1, the flags for Call 1 are (PADMY,GMG,SMG,pPOK), and for
Call 2 are (PADMY,GMG,SMG,POK,pPOK).  I don't know why they differ
between the calls, but I don't caer because SvOK() returns true for
both, and so DBD::MySQL works as expected.

I'll go away now and pester a Perl Internals list somewhere.  Do you
have any suggestions how I should proceed ?
I wouldn't even know what to call this problem.

regards,
Martin

Martin Waite wrote:

> Hi Patrick,
>
> I have compiled up v 3.0004 on Woody (Perl 5.6.1), and the script
> works properly.
>
> The problem seems to be tied to the version of Perl that is used.
>
> regards,
> Martin
>
> Martin Waite wrote:
>
>> Hi Patrick,
>>
>> I have changed the cancel subroutine to print out the substr expression:
>>
>> sub cancel {
>>  my ( $dcref ) = @_;
>>  print  "DCREF: $dcref\n";
>>  print "update update_bug set status = 5 where k = ? ", substr(
>> $dcref, -11 ), "\n";
>>  $dbh->do( "update update_bug set status = 5 where k = ?", undef,
>> substr( $dcref, -11 ) );
>> }
>>  
>>
>> The output from the program now is:
>>
>> martin@chadwick:~$ perl -w ~/ed/adhoc/update-bug
>> DCREF: 4000930012345671
>> update update_bug set status = 5 where k = ? 30012345671
>> DCREF: 4000930012345671
>> update update_bug set status = 5 where k = ? 30012345671
>> DCREF: 4000930012345671
>> update update_bug set status = 5 where k = ? 30012345671
>> DCREF: 4000930012345671
>> update update_bug set status = 5 where k = ? 30012345671
>>  
>>
>> Which is what I'd expect, however the query log still shows:
>>
>>                   4655 Query       SET AUTOCOMMIT=1
>>                   4655 Query       drop table if exists update_bug
>>                   4655 Query       create table update_bug( k int not
>> null primary key, status int not null )
>>                   4655 Query       update update_bug set status = 5
>> where k = '30012345671'
>>                   4655 Query       update update_bug set status = 5
>> where k = '30012345671'
>>                   4655 Query       update update_bug set status = 5
>> where k = '30012345671'
>>                   4655 Query       update update_bug set status = 5
>> where k = NULL
>>                   4655 Query       update update_bug set status = 5
>> where k = NULL
>>                   4655 Query       update update_bug set status = 5
>> where k = NULL
>>                   4655 Quit
>>  
>>
>> I have raised this issue through the MySQL Network, and they have
>> raised a bug.  They tried the script on Suse, and the same problem
>> appears.
>>
>> I have downloaded the latest DBD (3.0004) and the problem still
>> applies (this linked against the 5.0.20a client libraries).   Poking
>> around in dbdimp.c, I noticed that a whole lot of debug switches on
>> if you set dbis->debug to 2, so in mysql_st_internal_execute, I set
>> dbis->debug to 2, but then the problem goes away.   Very
>> frustrating.  (By the way, what is the proper way to set debugging on ?)
>>
>> My plan of action is to attempt to compile the woody DBD (v1.22 !) on
>> sarge/perl 5.8.4 and see if that works - but the version might be too
>> old to work with the new Perl.   Probably easier to compile the
>> newest DBD on woody against Perl 5.6 and see if the problem follows
>> with it.
>>
>> I notice in the release email for DBD 3.0004 that you say threading
>> must be switched off on Solaris.  The version of Perl on sarge /
>> ubuntu has threading switched on.   I don't know how much of this is
>> relevant, but below I include the output of Perl -V for the two hosts
>> the script fails on (Sarge and Ubuntu), and the one it works on (Woody).
>>
>> regards,
>> Martin
>>
>>
>> sarge: perl -V
>> Summary of my perl5 (revision 5 version 8 subversion 4) configuration:
>>  Platform:
>>    osname=linux, osvers=2.6.15, archname=i386-linux-thread-multi
>>    uname='linux ninsei 2.6.15 #1 smp preempt sat jan 7 12:47:52 pst
>> 2006 i686 gnulinux '
>>    config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN
>> -Dcccdlflags=-fPIC -Darchname=i386-linux -Dprefix=/usr
>> -Dprivlib=/usr/share/perl/5.8 -Darchlib=/usr/lib/perl/5.8
>> -Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5
>> -Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/local
>> -Dsitelib=/usr/local/share/perl/5.8.4
>> -Dsitearch=/usr/local/lib/perl/5.8.4 -Dman1dir=/usr/share/man/man1
>> -Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1
>> -Dsiteman3dir=/usr/local/man/man3 -Dman1ext=1 -Dman3ext=3perl
>> -Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Uusesfio -Uusenm
>> -Duseshrplib -Dlibperl=libperl.so.5.8.4 -Dd_dosuid -des'
>>    hint=recommended, useposix=true, d_sigaction=define
>>    usethreads=define use5005threads=undef useithreads=define
>> usemultiplicity=define
>>    useperlio=define d_sfio=undef uselargefiles=define usesocks=undef
>>    use64bitint=undef use64bitall=undef uselongdouble=undef
>>    usemymalloc=n, bincompat5005=undef
>>  Compiler:
>>    cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS
>> -DDEBIAN -fno-strict-aliasing -I/usr/local/include
>> -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
>>    optimize='-O2',
>>    cppflags='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS -DDEBIAN
>> -fno-strict-aliasing -I/usr/local/include'
>>    ccversion='', gccversion='3.3.5 (Debian 1:3.3.5-13)', 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 =' -L/usr/local/lib'
>>    libpth=/usr/local/lib /lib /usr/lib
>>    libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
>>    perllibs=-ldl -lm -lpthread -lc -lcrypt
>>    libc=/lib/libc-2.3.2.so, so=so, useshrplib=true,
>> libperl=libperl.so.5.8.4
>>    gnulibc_version='2.3.2'
>>  Dynamic Linking:
>>    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
>>    cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib'
>>
>>
>> Characteristics of this binary (from libperl):
>>  Compile-time options: MULTIPLICITY USE_ITHREADS USE_LARGE_FILES
>> PERL_IMPLICIT_CONTEXT
>>  Built under linux
>>  Compiled at Jan 12 2006 14:54:46
>>  @INC:
>>    /etc/perl
>>    /usr/local/lib/perl/5.8.4
>>    /usr/local/share/perl/5.8.4
>>    /usr/lib/perl5
>>    /usr/share/perl5
>>    /usr/lib/perl/5.8
>>    /usr/share/perl/5.8
>>    /usr/local/lib/site_perl
>>    .
>>
>>
>> Ubuntu: perl -V
>>
>> Summary of my perl5 (revision 5 version 8 subversion 4) configuration:
>>  Platform:
>>    osname=linux, osvers=2.6.8.1, archname=i386-linux-thread-multi
>>    uname='linux terranova 2.6.8.1 #1 smp sat feb 26 13:03:40 utc 2005
>> i686 gnulinux '
>>    config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN
>> -Dcccdlflags=-fPIC -Darchname=i386-linux -Dprefix=/usr
>> -Dprivlib=/usr/share/perl/5.8 -Darchlib=/usr/lib/perl/5.8
>> -Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5
>> -Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/local
>> -Dsitelib=/usr/local/share/perl/5.8.4
>> -Dsitearch=/usr/local/lib/perl/5.8.4 -Dman1dir=/usr/share/man/man1
>> -Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1
>> -Dsiteman3dir=/usr/local/man/man3 -Dman1ext=1 -Dman3ext=3perl
>> -Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Uusesfio -Uusenm
>> -Duseshrplib -Dlibperl=libperl.so.5.8.4 -Dd_dosuid -des'
>>    hint=recommended, useposix=true, d_sigaction=define
>>    usethreads=define use5005threads=undef useithreads=define
>> usemultiplicity=define
>>    useperlio=define d_sfio=undef uselargefiles=define usesocks=undef
>>    use64bitint=undef use64bitall=undef uselongdouble=undef
>>    usemymalloc=n, bincompat5005=undef
>>  Compiler:
>>    cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS
>> -DDEBIAN -fno-strict-aliasing -I/usr/local/include
>> -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
>>    optimize='-O2',
>>    cppflags='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS -DDEBIAN
>> -fno-strict-aliasing -I/usr/local/include'
>>    ccversion='', gccversion='3.3.4 (Debian 1:3.3.4-9ubuntu5)',
>> 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 =' -L/usr/local/lib'
>>    libpth=/usr/local/lib /lib /usr/lib
>>    libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
>>    perllibs=-ldl -lm -lpthread -lc -lcrypt
>>    libc=/lib/libc-2.3.2.so, so=so, useshrplib=true,
>> libperl=libperl.so.5.8.4
>>    gnulibc_version='2.3.2'
>>  Dynamic Linking:
>>    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
>>    cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib'
>>
>>
>> Characteristics of this binary (from libperl):
>>  Compile-time options: MULTIPLICITY USE_ITHREADS USE_LARGE_FILES
>> PERL_IMPLICIT_CONTEXT
>>  Built under linux
>>  Compiled at Mar  9 2005 11:10:00
>>  @INC:
>>    /etc/perl
>>    /usr/local/lib/perl/5.8.4
>>    /usr/local/share/perl/5.8.4
>>    /usr/lib/perl5
>>    /usr/share/perl5
>>    /usr/lib/perl/5.8
>>    /usr/share/perl/5.8
>>    /usr/local/lib/site_perl
>>    .
>>
>>
>> Woody: perl -V
>> Summary of my perl5 (revision 5.0 version 6 subversion 1) configuration:
>>  Platform:
>>    osname=linux, osvers=2.4.28-es, archname=i386-linux
>>    uname='linux gluck 2.4.28-es #1 smp wed jan 12 09:55:22 est 2005
>> i686 unknown '
>>    config_args='-Dccflags=-DDEBIAN -Dcccdlflags=-fPIC
>> -Darchname=i386-linux -Dprefix=/usr -Dprivlib=/usr/share/perl/5.6.1
>> -Darchlib=/usr/lib/perl/5.6.1 -Dvendorprefix=/usr
>> -Dvendorlib=/usr/share/perl5 -Dvendorarch=/usr/lib/perl5
>> -Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl/5.6.1
>> -Dsitearch=/usr/local/lib/perl/5.6.1 -Dman1dir=/usr/share/man/man1
>> -Dman3dir=/usr/share/man/man3 -Dman1ext=1 -Dman3ext=3perl
>> -Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Uusesfio -Duseshrplib
>> -Dlibperl=libperl.so.5.6.1 -Dd_dosuid -des'
>>    hint=recommended, useposix=true, d_sigaction=define
>>    usethreads=undef use5005threads=undef useithreads=undef
>> usemultiplicity=undef
>>    useperlio=undef d_sfio=undef uselargefiles=define usesocks=undef
>>    use64bitint=undef use64bitall=undef uselongdouble=undef
>>  Compiler:
>>    cc='cc', ccflags ='-DDEBIAN -fno-strict-aliasing
>> -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
>>    optimize='-O2',
>>    cppflags='-DDEBIAN -fno-strict-aliasing -I/usr/local/include'
>>    ccversion='', gccversion='2.95.4 20011002 (Debian prerelease)',
>> 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, usemymalloc=n, prototype=define
>>  Linker and Libraries:
>>    ld='cc', ldflags =' -L/usr/local/lib'
>>    libpth=/usr/local/lib /lib /usr/lib
>>    libs=-lgdbm -ldb -ldl -lm -lc -lcrypt
>>    perllibs=-ldl -lm -lc -lcrypt
>>    libc=/lib/libc-2.2.5.so, so=so, useshrplib=true,
>> libperl=libperl.so.5.6.1
>>  Dynamic Linking:
>>    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-rdynamic'
>>    cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib'
>>
>>
>> Characteristics of this binary (from libperl):
>>  Compile-time options: USE_LARGE_FILES
>>  Built under linux
>>  Compiled at Mar 18 2005 16:57:39
>>  @INC:
>>    /usr/local/lib/perl/5.6.1
>>    /usr/local/share/perl/5.6.1
>>    /usr/lib/perl5
>>    /usr/share/perl5
>>    /usr/lib/perl/5.6.1
>>    /usr/share/perl/5.6.1
>>    /usr/local/lib/site_perl/i386-linux
>>    /usr/local/lib/site_perl
>>    .
>>
>>
>>
>>
>> Patrick Galbraith wrote:
>>
>>> Martin,
>>>
>>> It doesn't look like a DBD::mysql problem to me. It has something to
>>> do with the script. What does the output of program show? Perhaps
>>> print out "print substr($dcref, -11) . "\n"; prior to each call of
>>> do to see that it's actually passing the value to the driver. Or,
>>> try it without the substring call. Try some variation to see if the
>>> problem is in the value being passed to do.
>>>
>>> regards,
>>>
>>> Patrick
>>>
>>> Martin Waite wrote:
>>>
>>>> Hi,
>>>>
>>>> I have come across a problem in DBD::MySQL while porting code from
>>>> Woody
>>>> to Sarge and Ubuntu (both hoary and breezy).
>>>>
>>>> The following script creates a simple test table and attempts to
>>>> perform
>>>> 6 updates.  The first 3 updates work correctly, but in the final 3
>>>> updates, the key is erroneously taken as NULL:
>>>>
>>>> #! /usr/bin/perl5 -w
>>>>
>>>> use strict;
>>>> use DBI;
>>>>
>>>> my $dbh = DBI->connect( "dbi:mysql:test:host=chadwick:port=3306",
>>>>             'testuser', 'test', {RaiseError=>1, PrintError=>0} );
>>>>
>>>>
>>>> $dbh->do( "drop table if exists update_bug" );
>>>> $dbh->do( "create table update_bug( k int not null primary key,
>>>> status int not null )" );
>>>>
>>>> my $v = '4000930012345671';
>>>>
>>>> $dbh->do( "update update_bug set status = 5 where k = ?", undef,
>>>> substr( $v, -11 ) );  # OK
>>>> $dbh->do( "update update_bug set status = 5 where k = ?", undef,
>>>> substr( $v, -11 ) );  # OK
>>>>
>>>> cancel( $v );  # OK
>>>> cancel( $v );  # bug - k is NULL
>>>> cancel( $v );  # bug - k is NULL
>>>> cancel( $v );  # bug - k is NULL
>>>>
>>>> sub cancel {
>>>>   my ( $dcref ) = @_;
>>>>   print  "DCREF: $dcref\n";
>>>>   $dbh->do( "update update_bug set status = 5 where k = ?", undef,
>>>> substr( $dcref, -11 ) );
>>>> }
>>>>
>>>>  
>>>> In the Query log of the 4.1.11 database we're connecting to, we see:
>>>>
>>>> 060526 14:24:52    4605 Connect     testuser@chadwick on test
>>>>                    4605 Query       SET AUTOCOMMIT=1
>>>>                    4605 Query       drop table if exists update_bug
>>>>                    4605 Query       create table update_bug( k int
>>>> not null primary key, status int not null )
>>>>                    4605 Query       update update_bug set status =
>>>> 5 where k = '30012345671'
>>>>                    4605 Query       update update_bug set status =
>>>> 5 where k = '30012345671'
>>>>                    4605 Query       update update_bug set status =
>>>> 5 where k = '30012345671'
>>>>                    4605 Query       update update_bug set status =
>>>> 5 where k = NULL
>>>>                    4605 Query       update update_bug set status =
>>>> 5 where k = NULL
>>>>                    4605 Query       update update_bug set status =
>>>> 5 where k = NULL
>>>>                    4605 Quit
>>>>
>>>>  
>>>> The problem seems to be related to the fact that a substring
>>>> expression
>>>> is passed as an argument to DBI::do, but only when the DBI::do is
>>>> called
>>>> within a subroutine.
>>>>
>>>> I'm stumped here.  Is this a bug in Perl or DBD::MySQL, or just the
>>>> versions on Sarge and Ubuntu ?
>>>>
>>>> regards,
>>>> Martin
>>>>
>>>>
>>>>
>>>>
>>>>   
>>>
>>>
>>>
>>>
>>>
>>
>>
>
>


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