NAME

Troubleshooting mod_perl problems

Description

Frequently encountered problems (warnings and fatal errors) and their troubleshooting.

Building and Installation

Configuration and Startup

Segmentation Fault when Using DBI

Update DBI to at least version 1.31.

Shutdown and Restart

Code Parsing and Compilation

Runtime

C Libraries Don't See %ENV Entries Set by Perl Code

For example some people have reported problems with DBD::Oracle (whose guts are implemented in C), which doesn't see environment variables (like ORACLE_HOME, ORACLE_SID, etc.) set in the perl script and therefore fails to connect.

The issue is that the C array environ[] is not thread-safe. Therefore mod_perl 2.0 unties %ENV from the underlying environ[] array under the perl-script handler.

The DBD::Oracle driver or client library uses getenv() (which fetches from the environ[] array). When %ENV is untied from environ[], Perl code will see %ENV changes, but C code will not.

The modperl handler does not untie %ENV from environ[]. Still one should avoid setting %ENV values whenever possible. And if it is required, should be done at startup time.

In the particular case of the DBD:: drivers, you can set the variables that don't change ($ENV{ORACLE_HOME} and $ENV{NLS_LANG} in the startup file, and those that change pass via the connect() method, e.g.:

  my $sid      = 'ynt0';
  my $dsn      = 'dbi:Oracle:';
  my $user     = 'username/password';
  my $password = '';
  $dbh = DBI->connect("$dsn$sid", $user, $password)
      or die "Cannot connect: " . $DBI::errstr;

Also remember that DBD::Oracle requires that ORACLE_HOME (and any other stuff like NSL_LANG stuff) be in %ENV when DBD::Oracle is loaded (which might happen indirectly via the DBI module. Therefore you need to make sure that wherever that load happens %ENV is properly set by that time.

Error about not finding Apache.pm with CGI.pm

You need to install at least version 2.87 of CGI.pm to work under mod_perl 2.0, as earlier CGI.pm versions aren't mod_perl 2.0 aware.

Maintainers

Maintainer is the person(s) you should contact with updates, corrections and patches.

• Stas Bekman

Authors

• Stas Bekman

Only the major authors are listed above. For contributors see the Changes file.