By MandyWaite on Oct 03, 2008
We found in recent testing while integrating Ruby 1.8.6 Patch Level 287 into Solaris Nevada that it's possible to create a situation where Ruby on Rails applications will sometimes crash with a Segmentation Fault. We found that the MySQL native gem when installed, had been built with the mysql.h C header file from MySQL 5.0 but had been linked with an older version of the MySQL client library. This comes about if you install the gem as follows:
gem install mysql -- --with-mysql-dir=/usr/mysql/5.0
In this case the compiler is able to find the C headers in /usr/mysql/5.0/include but because the client library is actually located in /usr/mysql/5.0/lib/mysql/lib, the linker isn't able to find it. As we include /usr/sfw/lib in the build and runtime linker paths for native Ruby Gems, it is able to find the MySQL 4.0 client library and at runtime it links with that. Not surprisingly the MySQL 5.0 C header won't work with the MySQL 4.0 client library, what is surprising is that it works at all and doesn't crash as soon as you try to access MySQL from Ruby.
The solution is to install the gem without specifying any flags, in which case it will compile and link with the MySQL4.0 client, or preferably to specify the path to the include and lib directories of MySQL 5.0. So use either of the following:
gem install mysql -- --with-mysql-lib=/usr/mysql/5.0/lib/mysql -- with-mysql-include=/usr/mysql/5.0/include
gem install mysql
This is not a problem on OpenSolaris as the MySQL 4.0 client library is not there by default, just remember that just using --with-mysql-dir= may not always be enough information for the compiler and linker to do the right thing.