NAME

       Imager::Threads - Imager and threads

SYNOPSIS

         use Imager;
         use threads;
         Imager->preload;

         threads->create(...);

DESCRIPTION

       Starting from version 0.94 Imager attempts to work safely with perl's "ithreads".

       Previous versions stored some state in global variables, in particular the internal error stack.

       However there are some limitations:

       •   Imager's  debug  malloc  isn't  thread  safe and will never be.  Imager's debug malloc is disabled by
           default.

       •   "libtiff", which Imager uses for TIFF file support is not  thread  safe,  "Imager::File::TIFF"  works
           around this by single-threading its access to "libtiff".

       •   "giflib", which Imager uses for GIF support is not thread safe before version 5.  "Imager::File::GIF"
           works around this by single threading its access to "giflib".

       •   "T1Lib",  used  by one of Imager's font drivers, is not thread safe.  "Imager::Font::T1" works around
           this by single threading access.

       •   killing a thread reading or writing TIFF or GIF files, or using T1 fonts  through  "Imager::Font::T1"
           may  deadlock other threads when they attempt to read or write TIFF or GIF files, or work with Type 1
           fonts.

       •   Fill, font, color or I/O layer objects created in one thread are not valid for use in child  threads.
           If  you  manage  to  duplicate  such an object in another thread, you get to keep both pieces when it
           breaks.

       Note that if you have another module using "libtiff", "giflib" or "t1lib" it may interact  with  Imager's
       use  of  those  libraries  in  a  threaded environment, since there's no way to co-ordinate access to the
       global information "libtiff", "giflib" and "t1lib" maintain.

       Imager currently doesn't use threads itself, except for testing its threads support.

SEE ALSO

       Imager, "threads"

AUTHOR

       Tony Cook <tony@cpan.org>

perl v5.38.2                                       2024-04-01                               Imager::Threads(3pm)