Problem using mod_perl-1.26 with perl 5.6.1 and XML::Parser
Hi gang, I am fairly new to mod_perl, but I would like to share my recent experience and hope someone might offer some insight into my troubles. Last week I whipped together a simple perl module that used XML::Simple ( a wrapper for XML::Parser) to parse some POST'd content. Once parsed the resulting data was munched a bit and then POST'd to another web server. Like everything perl it was quick to implement and ran quick as well. My problems came along when I moved my module to another server. All of sudden Apache would segfault in the Expat library code when my module parsed the content. I noticed that I had different versions of XML::Parser on the different machines (2.29 vs. 2.30). XML::Parser-2.29 was the one on the working instance so I downgraded the box that was segfaulting. When I down graded the segfaults went away but a nasty little problem showed up latter in the module where the data being sent in my module's post was getting corrupted. I narrowed down the problem to the call to running the XML parser being related to the data corruption. At this point I found this mail list and searched the archive. There were lots of references to the "Expat" problem where Apache itself uses a copy of Expat and a XML::Parser would use a different version of the Expat. There was discussion about required configuration parameters to mod perl, but more importantly there was a post mentioning that Apache 1.3.22 made the whole problem go away. Feeling inspired by my new found knowledge of the problem, I decided a clean install of the new apache was in order. To be safe, I reinstalled RedHat 7.1 without RedHat's apache. I uninstalled perl 5.6.0 that came with RH7.1 and installed perl 5.6.1. I followed the "simple" mod_perl install instructions that builds apache with perl statically linked. My resulting install didn't segfault, but my nasty bug was still there. At this point I went back and fully duplicated the working implementation: Apache 1.3.19, mod_perl 1.26 perl-5.005_3 and XML::Parser-2.29. The originally working system was on RH 6.2, and this configuration worked on my new machine using RH 7.1. This configuration was built with the following commands: tar zxf apache_1.3.19.tar.gz cd apache_1.3.19 ./configure --prefix=/lsurf/apache --enable-shared=max --enable-module=all make make install cd .. tar zxf mod_perl-1.26.tar.gz cd mod_perl-1.26 perl Makefile.PL USE_APXS=1 APACHE_PREFIX=/lsurf/apache EVERYTHING=1 make make install Now that I had something reproducible, I continued. I rebuilt using Apache 1.3.22 just like above, and everything continued to work. I upgraded to XML::Parser-2.30, and things continued to work. It was only when I went from perl 5.005_3 to 5.6.1 did my module break. As I said above I tried a statically linked apache. I also tried building Apache 1.3.22 as above with perl 5.6.1 and my code failed with both XML::Parser-2.29 and XML::Parser-2.30. Whatever way I tried using perl 5.6.1 I had my nasty problem. When configuring Apache 1.3.22 I noticed it said it was using the system's libexpat which was installed with RH. XML::Parser-2.29 uses its own copy of expat, but XML::Parser-2.30 uses the system libexpat. As I said with perl 5.005_3 I was able to use either version of XML::Parser. In the end I have a working implementation using perl-5.005_3, but I'd sure feel better using the "latest stable perl", and it should work as far as I can tell. If anyone has some suggestions I'd be willing to give them a try. Thanks for your patience if you read this long winded post. Matthew
RE: Problem using mod_perl-1.26 with perl 5.6.1 and XML::Parser
> -Original Message- > From: Matthew H. Gerlach [mailto:[EMAIL PROTECTED]] > > Now that I had something reproducible, I continued. I rebuilt using > Apache 1.3.22 just like above, and everything continued to work. I > upgraded to XML::Parser-2.30, and things continued to work. > It was only > when I went from perl 5.005_3 to 5.6.1 did my module break. As I said > above I tried a statically linked apache. I also tried > building Apache > 1.3.22 as above with perl 5.6.1 and my code failed with both > XML::Parser-2.29 and XML::Parser-2.30. Whatever way I tried > using perl > 5.6.1 I had my nasty problem. > > When configuring Apache 1.3.22 I noticed it said it was using the > system's libexpat which was installed with RH. XML::Parser-2.29 uses > its own copy of expat, but XML::Parser-2.30 uses the system libexpat. > As I said with perl 5.005_3 I was able to use either version of > XML::Parser. >From what I can tell from the Apache 1.3.22 build, here's how to get it stable: 1. Install libexpat. 2. Install perl 3. Install XML::Parser 2.30 4. Install mod_perl and Apache, telling mod_perl to build Apache for you. ** Do not use APXS to build mod_perl ** The recipe in the AxKit INSTALL file seems to work best for people doing XML stuff inside mod_perl: $ perl Makefile.PL \ > EVERYTHING=1 \ > USE_APACI=1 \ > DYNAMIC=1 \ > APACHE_PREFIX=/opt/apache \ > APACHE_SRC=../apache_1.3.22/src \ > DO_HTTPD=1 \ > APACI_ARGS="--enable-module=so --enable-shared=info > --enable-shared=proxy --enable-shared=rewrite > --enable-shared=log_agent" $ make $ su $ make install However, that also builds Apache with --disable-rule=expat, so it might kinda defeat your purpose :-) If you *really* need the expat in Apache, I think you can add in there --enable-rule=expat, but I haven't tried it. If all that fails, switch to XML::LibXML or XML::SAX::PurePerl (actually, think about doing that anyway :-) Matt. _ This message has been checked for all known viruses by Star Internet delivered through the MessageLabs Virus Scanning Service. For further information visit http://www.star.net.uk/stats.asp or alternatively call Star Internet for details on the Virus Scanning Service.
Re: Problem using mod_perl-1.26 with perl 5.6.1 and XML::Parser
Just to follow up. I took your advice on building building modperl. My actual command was as follows: perl Makefile.PL \ EVERYTHING=1 \ USE_APACI=1 \ APACHE_PREFIX=/lsurf/wohg \ APACHE_SRC=../$APACHE/src \ DO_HTTP=1 \ APACI_ARGS="--enable-rule=expat --enable-module=so --enable-shared=info \ --enable-shared=proxy --enable-shared=rewrite" I first tried this with perl 5.005_3 with no problems. I then upgraded to perl 5.6.1, reinstalled the XML::Parser 2.30, and rebuild modperl/apache. The nasty bug showed back up. At this point it still looks like I'm SOL using XML::Parser with perl 5.6.1 under modper. I did download and install XML::LibXML and started playing with it. I'm actually using XML::Parser via XML::Simple to put short XML "messages" into handy 'data structures'. Maybe I should make an XML::LibXML::Simple :) Thanks for the help, Matthew Matt Sergeant wrote: > > -Original Message- > > From: Matthew H. Gerlach [mailto:[EMAIL PROTECTED]] > > > > Now that I had something reproducible, I continued. I rebuilt using > > Apache 1.3.22 just like above, and everything continued to work. I > > upgraded to XML::Parser-2.30, and things continued to work. > > It was only > > when I went from perl 5.005_3 to 5.6.1 did my module break. As I said > > above I tried a statically linked apache. I also tried > > building Apache > > 1.3.22 as above with perl 5.6.1 and my code failed with both > > XML::Parser-2.29 and XML::Parser-2.30. Whatever way I tried > > using perl > > 5.6.1 I had my nasty problem. > > > > When configuring Apache 1.3.22 I noticed it said it was using the > > system's libexpat which was installed with RH. XML::Parser-2.29 uses > > its own copy of expat, but XML::Parser-2.30 uses the system libexpat. > > As I said with perl 5.005_3 I was able to use either version of > > XML::Parser. > > >From what I can tell from the Apache 1.3.22 build, here's how to get it > stable: > > 1. Install libexpat. > 2. Install perl > 3. Install XML::Parser 2.30 > 4. Install mod_perl and Apache, telling mod_perl to build Apache for you. > ** Do not use APXS to build mod_perl ** > > The recipe in the AxKit INSTALL file seems to work best for people doing XML > stuff inside mod_perl: > > $ perl Makefile.PL \ > > EVERYTHING=1 \ > > USE_APACI=1 \ > > DYNAMIC=1 \ > > APACHE_PREFIX=/opt/apache \ > > APACHE_SRC=../apache_1.3.22/src \ > > DO_HTTPD=1 \ > > APACI_ARGS="--enable-module=so --enable-shared=info > > --enable-shared=proxy --enable-shared=rewrite > > --enable-shared=log_agent" > $ make > $ su > $ make install > > However, that also builds Apache with --disable-rule=expat, so it might > kinda defeat your purpose :-) If you *really* need the expat in Apache, I > think you can add in there --enable-rule=expat, but I haven't tried it. > > If all that fails, switch to XML::LibXML or XML::SAX::PurePerl (actually, > think about doing that anyway :-) > > Matt. > > _ > This message has been checked for all known viruses by Star Internet > delivered through the MessageLabs Virus Scanning Service. For further > information visit http://www.star.net.uk/stats.asp or alternatively call > Star Internet for details on the Virus Scanning Service.
Re: Problem using mod_perl-1.26 with perl 5.6.1 and XML::Parser
"Matthew H. Gerlach" wrote: > > Just to follow up. I took your advice on building building modperl. My actual > command was as follows: > > perl Makefile.PL \ > EVERYTHING=1 \ > USE_APACI=1 \ > APACHE_PREFIX=/lsurf/wohg \ > APACHE_SRC=../$APACHE/src \ > DO_HTTP=1 \ > APACI_ARGS="--enable-rule=expat --enable-module=so --enable-shared=info \ > --enable-shared=proxy --enable-shared=rewrite" > > I first tried this with perl 5.005_3 with no problems. I then upgraded to perl > 5.6.1, reinstalled the XML::Parser 2.30, and rebuild modperl/apache. The nasty > bug showed back up. At this point it still looks like I'm SOL using > XML::Parser with perl 5.6.1 under modper. > > I did download and install XML::LibXML and started playing with it. I'm > actually using XML::Parser via XML::Simple to put short XML "messages" into > handy 'data structures'. Maybe I should make an XML::LibXML::Simple :) > i would say that XML::LibXML is the most stable modules ive used everything else perl has failed for the X3D parsing tool i made: http://drfrog.fdns.net/perl/parsex3d.pl this will have a much nicer home at web3d.org at some point soon they found a bug in it on freebsd timezone related iirc
