Imager::Threads - Imager and threads |
Imager::Threads - Imager and threads
use Imager; use threads; Imager->preload;
threads->create(...);
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:
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.
Imager, threads
Tony Cook <tony@cpan.org>
Imager::Threads - Imager and threads |