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