Apache: The Definitive Guide, 3rd Edition

Opening and Closing Files

Another consequence of scripts remaining permanently loaded is that opened files are not automatically closed when a script terminates — because it doesn’t terminate until Apache is shut down. Failure to do this will eat up memory and file handles. It is important therefore that every opened file should be explicitly closed. However, it is not good enough just to use close() conscientiously because something may go wrong in the script, causing it to exit without executing the close() statement. The cure is to use the I/O module. This has the effect that the file handle is closed when the block it is in goes out of scope:

use IO;

...
my $fh=IO::File->new("name") or die $!;
$fh->print($text);
#or
$stuff=<$fh>;
# $fh closes automatically

Alternatively:

use Symbol;
...
My $fh=Symbol::gensym;
Open $fh or die $!;
....
#automatic close

Under Perl 5.6.0 this is enough:

open my $fh, $filename or die $!;
...
# automatic close