threads - Perl extension allowing use of interpreter based threads from perl |
threads - Perl extension allowing use of interpreter based threads from perl
use threads;
sub start_thread { print "Thread started\n"; }
my $thread = threads->create("start_thread","argument"); my $thread2 = $thread->create(sub { print "I am a thread"},"argument"); my $thread3 = async { foreach (@files) { ... } };
$thread->join(); $thread->detach();
$thread = threads->self(); $thread = threads->object( $tid );
$thread->tid(); threads->tid(); threads->self->tid();
threads->yield();
threads->list();
Perl 5.6 introduced something called interpreter threads. Interpreter threads are different from ``5005threads'' (the thread model of Perl 5.005) by creating a new perl interpreter per thread and not sharing any data or state between threads by default.
Prior to perl 5.8 this has only been available to people embedding
perl and for emulating fork()
on windows.
The threads API is loosely based on the old Thread.pm API. It is very important to note that variables are not shared between threads, all variables are per default thread local. To use shared variables one must use threads::shared.
It is also important to note that you must enable threads by doing
use threads
as early as possible in the script itself and that it
is not possible to enable threading inside an eval ""
, do
,
require
, or use
. In particular, if you are intending to share
variables with threads::shared, you must use threads
before you
use threads::shared
and threads
will emit a warning if you do
it the other way around.
new()
method is an alias for create().
join()
will return the return values of the entry point
function. If the thread has been detached, an error will be thrown.
If the program exits without all other threads having been either
joined or detached, then a warning will be issued. (A program exits
either because one of its threads explicitly calls exit(), or in the
case of the main thread, reaches the end of the main program file.)
NB the class method threads->tid()
is a quick way to get the
current thread id if you don't have your thread object handy.
You may do use threads qw(yield)
then use just a bare yield
in your
code.
async
creates a thread to execute the block immediately following
it. This block is treated as an anonymous sub, and so must have a
semi-colon after the closing brace. Like threads->new
, async
returns a thread object.
The current implementation of threads has been an attempt to get a correct threading system working that could be built on, and optimized, in newer versions of perl.
Currently the overhead of creating a thread is rather large, also the cost of returning values can be large. These are areas were there most likely will be work done to optimize what data that needs to be cloned.
This will possibly be fixed in later versions of perl.
=item tid is I32
The thread id is a 32 bit integer, it can potentially overflow. This might be fixed in a later version of perl.
fork()
inside
BEGIN blocks is an equally losing proposition, since it has been
implemented in very much the same way as threads.)
perl -V
),
signal handling is not threadsafe.
Arthur Bergman <arthur at contiller.se>
threads is released under the same license as Perl.
Thanks to
Richard Soderberg <rs at crystalflame.net> Helping me out tons, trying to find reasons for races and other weird bugs!
Simon Cozens <simon at brecon.co.uk> Being there to answer zillions of annoying questions
Rocco Caputo <troc at netrus.net>
Vipul Ved Prakash <mail at vipul.net> Helping with debugging.
please join perl-ithreads@perl.org for more information
the threads::shared manpage, the perlthrtut manpage, http://www.perl.com/pub/a/2002/06/11/threads.html, the perlcall manpage, the perlembed manpage, the perlguts manpage
threads - Perl extension allowing use of interpreter based threads from perl |