[ViewVC] Diff of: cvs/AnyEvent-Fork/Fork.pm

Comparing AnyEvent-Fork/Fork.pm (file contents):
Revision 1.26 by root, Sat Apr 6 08:58:51 2013 UTC vs.
Revision 1.37 by root, Sat Apr 6 20:06:39 2013 UTC

…		…
152		152
153	# now $master_filehandle is connected to the	153	# now $master_filehandle is connected to the
154	# $slave_filehandle in the new process.	154	# $slave_filehandle in the new process.
155	});	155	});
156		156
157	# MyModule::worker might look like this	157	C<MyModule> might look like this:
		158
		159	package MyModule;
		160
158	sub MyModule::worker {	161	sub worker {
159	my ($slave_filehandle) = @_;	162	my ($slave_filehandle) = @_;
160		163
161	# now $slave_filehandle is connected to the $master_filehandle	164	# now $slave_filehandle is connected to the $master_filehandle
162	# in the original prorcess. have fun!	165	# in the original prorcess. have fun!
163	}	166	}
…		…
182	}	185	}
183		186
184	# now do other things - maybe use the filehandle provided by run	187	# now do other things - maybe use the filehandle provided by run
185	# to wait for the processes to die. or whatever.	188	# to wait for the processes to die. or whatever.
186		189
187	# My::Server::run might look like this	190	C<My::Server> might look like this:
188	sub My::Server::run {	191
		192	package My::Server;
		193
		194	sub run {
189	my ($slave, $listener, $id) = @_;	195	my ($slave, $listener, $id) = @_;
190		196
191	close $slave; # we do not use the socket, so close it to save resources	197	close $slave; # we do not use the socket, so close it to save resources
192		198
193	# we could go ballistic and use e.g. AnyEvent here, or IO::AIO,	199	# we could go ballistic and use e.g. AnyEvent here, or IO::AIO,
…		…
197	}	203	}
198	}	204	}
199		205
200	=head2 use AnyEvent::Fork as a faster fork+exec	206	=head2 use AnyEvent::Fork as a faster fork+exec
201		207
202	This runs /bin/echo hi, with stdout redirected to /tmp/log and stderr to	208	This runs C</bin/echo hi>, with stdandard output redirected to /tmp/log
203	the communications socket. It is usually faster than fork+exec, but still	209	and standard error redirected to the communications socket. It is usually
204	let's you prepare the environment.	210	faster than fork+exec, but still lets you prepare the environment.
205		211
206	open my $output, ">/tmp/log" or die "$!";	212	open my $output, ">/tmp/log" or die "$!";
207		213
208	AnyEvent::Fork	214	AnyEvent::Fork
209	->new	215	->new
…		…
309	my ($fork_fh) = @_;	315	my ($fork_fh) = @_;
310	});	316	});
311		317
312	=back	318	=back
313		319
314	=head1 FUNCTIONS	320	=head1 THE C<AnyEvent::Fork> CLASS
		321
		322	This module exports nothing, and only implements a single class -
		323	C<AnyEvent::Fork>.
		324
		325	There are two class constructors that both create new processes - C<new>
		326	and C<new_exec>. The C<fork> method creates a new process by forking an
		327	existing one and could be considered a third constructor.
		328
		329	Most of the remaining methods deal with preparing the new process, by
		330	loading code, evaluating code and sending data to the new process. They
		331	usually return the process object, so you can chain method calls.
		332
		333	If a process object is destroyed before calling its C<run> method, then
		334	the process simply exits. After C<run> is called, all responsibility is
		335	passed to the specified function.
		336
		337	As long as there is any outstanding work to be done, process objects
		338	resist being destroyed, so there is no reason to store them unless you
		339	need them later - configure and forget works just fine.
315		340
316	=over 4	341	=over 4
317		342
318	=cut	343	=cut
319		344
…		…
329	use IO::FDPass;	354	use IO::FDPass;
330		355
331	our $VERSION = 0.5;	356	our $VERSION = 0.5;
332		357
333	our $PERL; # the path to the perl interpreter, deduces with various forms of magic	358	our $PERL; # the path to the perl interpreter, deduces with various forms of magic
334
335	=item my $pool = new AnyEvent::Fork key => value...
336
337	Create a new process pool. The following named parameters are supported:
338		359
339	=over 4	360	=over 4
340		361
341	=back	362	=back
342		363
…		…
438	Create a new "empty" perl interpreter process and returns its process	459	Create a new "empty" perl interpreter process and returns its process
439	object for further manipulation.	460	object for further manipulation.
440		461
441	The new process is forked from a template process that is kept around	462	The new process is forked from a template process that is kept around
442	for this purpose. When it doesn't exist yet, it is created by a call to	463	for this purpose. When it doesn't exist yet, it is created by a call to
443	C<new_exec> and kept around for future calls.	464	C<new_exec> first and then stays around for future calls.
444
445	When the process object is destroyed, it will release the file handle
446	that connects it with the new process. When the new process has not yet
447	called C<run>, then the process will exit. Otherwise, what happens depends
448	entirely on the code that is executed.
449		465
450	=cut	466	=cut
451		467
452	sub new {	468	sub new {
453	my $class = shift;	469	my $class = shift;
…		…
543	}	559	}
544		560
545	=item $pid = $proc->pid	561	=item $pid = $proc->pid
546		562
547	Returns the process id of the process I<iff it is a direct child of the	563	Returns the process id of the process I<iff it is a direct child of the
548	process> running AnyEvent::Fork, and C<undef> otherwise.	564	process running AnyEvent::Fork>, and C<undef> otherwise.
549		565
550	Normally, only processes created via C<< AnyEvent::Fork->new_exec >> and	566	Normally, only processes created via C<< AnyEvent::Fork->new_exec >> and
551	L<AnyEvent::Fork::Template> are direct children, and you are responsible	567	L<AnyEvent::Fork::Template> are direct children, and you are responsible
552	to clean up their zombies when they die.	568	to clean up their zombies when they die.
553		569
554	All other processes are not direct children, and will be cleaned up by	570	All other processes are not direct children, and will be cleaned up by
555	AnyEvent::Fork.	571	AnyEvent::Fork itself.
556		572
557	=cut	573	=cut
558		574
559	sub pid {	575	sub pid {
560	$_[0][0]	576	$_[0][0]
…		…
571		587
572	The code will usually be executed after this call returns, and there is no	588	The code will usually be executed after this call returns, and there is no
573	way to pass anything back to the calling process. Any evaluation errors	589	way to pass anything back to the calling process. Any evaluation errors
574	will be reported to stderr and cause the process to exit.	590	will be reported to stderr and cause the process to exit.
575		591
576	If you want to execute some code to take over the process (see the	592	If you want to execute some code (that isn't in a module) to take over the
577	"fork+exec" example in the SYNOPSIS), you should compile a function via	593	process, you should compile a function via C<eval> first, and then call
578	C<eval> first, and then call it via C<run>. This also gives you access to	594	it via C<run>. This also gives you access to any arguments passed via the
579	any arguments passed via the C<send_xxx> methods, such as file handles.	595	C<send_xxx> methods, such as file handles. See the L<use AnyEvent::Fork as
		596	a faster fork+exec> example to see it in action.
580		597
581	Returns the process object for easy chaining of method calls.	598	Returns the process object for easy chaining of method calls.
582		599
583	=cut	600	=cut
584		601
…		…
610	=item $proc = $proc->send_fh ($handle, ...)	627	=item $proc = $proc->send_fh ($handle, ...)
611		628
612	Send one or more file handles (I<not> file descriptors) to the process,	629	Send one or more file handles (I<not> file descriptors) to the process,
613	to prepare a call to C<run>.	630	to prepare a call to C<run>.
614		631
615	The process object keeps a reference to the handles until this is done,	632	The process object keeps a reference to the handles until they have
616	so you must not explicitly close the handles. This is most easily	633	been passed over to the process, so you must not explicitly close the
617	accomplished by simply not storing the file handles anywhere after passing	634	handles. This is most easily accomplished by simply not storing the file
618	them to this method.	635	handles anywhere after passing them to this method - when AnyEvent::Fork
		636	is finished using them, perl will automatically close them.
619		637
620	Returns the process object for easy chaining of method calls.	638	Returns the process object for easy chaining of method calls.
621		639
622	Example: pass a file handle to a process, and release it without	640	Example: pass a file handle to a process, and release it without
623	closing. It will be closed automatically when it is no longer used.	641	closing. It will be closed automatically when it is no longer used.
…		…
639	}	657	}
640		658
641	=item $proc = $proc->send_arg ($string, ...)	659	=item $proc = $proc->send_arg ($string, ...)
642		660
643	Send one or more argument strings to the process, to prepare a call to	661	Send one or more argument strings to the process, to prepare a call to
644	C<run>. The strings can be any octet string.	662	C<run>. The strings can be any octet strings.
645		663
646	The protocol is optimised to pass a moderate number of relatively short	664	The protocol is optimised to pass a moderate number of relatively short
647	strings - while you can pass up to 4GB of data in one go, this is more	665	strings - while you can pass up to 4GB of data in one go, this is more
648	meant to pass some ID information or other startup info, not big chunks of	666	meant to pass some ID information or other startup info, not big chunks of
649	data.	667	data.
…		…
665	Enter the function specified by the function name in C<$func> in the	683	Enter the function specified by the function name in C<$func> in the
666	process. The function is called with the communication socket as first	684	process. The function is called with the communication socket as first
667	argument, followed by all file handles and string arguments sent earlier	685	argument, followed by all file handles and string arguments sent earlier
668	via C<send_fh> and C<send_arg> methods, in the order they were called.	686	via C<send_fh> and C<send_arg> methods, in the order they were called.
669		687
		688	The process object becomes unusable on return from this function - any
		689	further method calls result in undefined behaviour.
		690
670	The function name should be fully qualified, but if it isn't, it will be	691	The function name should be fully qualified, but if it isn't, it will be
671	looked up in the main package.	692	looked up in the C<main> package.
672		693
673	If the called function returns, doesn't exist, or any error occurs, the	694	If the called function returns, doesn't exist, or any error occurs, the
674	process exits.	695	process exits.
675		696
676	Preparing the process is done in the background - when all commands have	697	Preparing the process is done in the background - when all commands have
677	been sent, the callback is invoked with the local communications socket	698	been sent, the callback is invoked with the local communications socket
678	as argument. At this point you can start using the socket in any way you	699	as argument. At this point you can start using the socket in any way you
679	like.	700	like.
680
681	The process object becomes unusable on return from this function - any
682	further method calls result in undefined behaviour.
683		701
684	If the communication socket isn't used, it should be closed on both sides,	702	If the communication socket isn't used, it should be closed on both sides,
685	to save on kernel memory.	703	to save on kernel memory.
686		704
687	The socket is non-blocking in the parent, and blocking in the newly	705	The socket is non-blocking in the parent, and blocking in the newly
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762	479 vfork+execs per second, using AnyEvent::Fork->new_exec	780	479 vfork+execs per second, using AnyEvent::Fork->new_exec
763		781
764	So how can C<< AnyEvent->new >> be faster than a standard fork, even	782	So how can C<< AnyEvent->new >> be faster than a standard fork, even
765	though it uses the same operations, but adds a lot of overhead?	783	though it uses the same operations, but adds a lot of overhead?
766		784
767	The difference is simply the process size: forking the 6MB process takes	785	The difference is simply the process size: forking the 5MB process takes
768	so much longer than forking the 2.5MB template process that the overhead	786	so much longer than forking the 2.5MB template process that the extra
769	introduced is canceled out.	787	overhead introduced is canceled out.
770		788
771	If the benchmark process grows, the normal fork becomes even slower:	789	If the benchmark process grows, the normal fork becomes even slower:
772		790
773	1340 new processes, manual fork in a 20MB process	791	1340 new processes, manual fork of a 20MB process
774	731 new processes, manual fork in a 200MB process	792	731 new processes, manual fork of a 200MB process
775	235 new processes, manual fork in a 2000MB process	793	235 new processes, manual fork of a 2000MB process
776		794
777	What that means (to me) is that I can use this module without having a	795	What that means (to me) is that I can use this module without having a bad
778	very bad conscience because of the extra overhead required to start new	796	conscience because of the extra overhead required to start new processes.
779	processes.
780		797
781	=head1 TYPICAL PROBLEMS	798	=head1 TYPICAL PROBLEMS
782		799
783	This section lists typical problems that remain. I hope by recognising	800	This section lists typical problems that remain. I hope by recognising
784	them, most can be avoided.	801	them, most can be avoided.
785		802
786	=over 4	803	=over 4
787		804
788	=item "leaked" file descriptors for exec'ed processes	805	=item leaked file descriptors for exec'ed processes
789		806
790	POSIX systems inherit file descriptors by default when exec'ing a new	807	POSIX systems inherit file descriptors by default when exec'ing a new
791	process. While perl itself laudably sets the close-on-exec flags on new	808	process. While perl itself laudably sets the close-on-exec flags on new
792	file handles, most C libraries don't care, and even if all cared, it's	809	file handles, most C libraries don't care, and even if all cared, it's
793	often not possible to set the flag in a race-free manner.	810	often not possible to set the flag in a race-free manner.
…		…
813	libraries or the code that leaks those file descriptors.	830	libraries or the code that leaks those file descriptors.
814		831
815	Fortunately, most of these leaked descriptors do no harm, other than	832	Fortunately, most of these leaked descriptors do no harm, other than
816	sitting on some resources.	833	sitting on some resources.
817		834
818	=item "leaked" file descriptors for fork'ed processes	835	=item leaked file descriptors for fork'ed processes
819		836
820	Normally, L<AnyEvent::Fork> does start new processes by exec'ing them,	837	Normally, L<AnyEvent::Fork> does start new processes by exec'ing them,
821	which closes file descriptors not marked for being inherited.	838	which closes file descriptors not marked for being inherited.
822		839
823	However, L<AnyEvent::Fork::Early> and L<AnyEvent::Fork::Template> offer	840	However, L<AnyEvent::Fork::Early> and L<AnyEvent::Fork::Template> offer
…		…
832		849
833	The solution is to either not load these modules before use'ing	850	The solution is to either not load these modules before use'ing
834	L<AnyEvent::Fork::Early> or L<AnyEvent::Fork::Template>, or to delay	851	L<AnyEvent::Fork::Early> or L<AnyEvent::Fork::Template>, or to delay
835	initialising them, for example, by calling C<init Gtk2> manually.	852	initialising them, for example, by calling C<init Gtk2> manually.
836		853
837	=item exit runs destructors	854	=item exiting calls object destructors
838		855
839	This only applies to users of Lc<AnyEvent::Fork:Early> and	856	This only applies to users of Lc<AnyEvent::Fork:Early> and
840	L<AnyEvent::Fork::Template>.	857	L<AnyEvent::Fork::Template>.
841		858
842	When a process created by AnyEvent::Fork exits, it might do so by calling	859	When a process created by AnyEvent::Fork exits, it might do so by calling
…		…
864	to make it so, mostly due to the bloody broken perl that nobody seems to	881	to make it so, mostly due to the bloody broken perl that nobody seems to
865	care about. The fork emulation is a bad joke - I have yet to see something	882	care about. The fork emulation is a bad joke - I have yet to see something
866	useful that you can do with it without running into memory corruption	883	useful that you can do with it without running into memory corruption
867	issues or other braindamage. Hrrrr.	884	issues or other braindamage. Hrrrr.
868		885
869	Cygwin perl is not supported at the moment, as it should implement fd	886	Cygwin perl is not supported at the moment due to some hilarious
870	passing, but doesn't, and rolling my own is hard, as cygwin doesn't	887	shortcomings of its API - see L<IO::FDPoll> for more details.
871	support enough functionality to do it.
872		888
873	=head1 SEE ALSO	889	=head1 SEE ALSO
874		890
875	L<AnyEvent::Fork::Early> (to avoid executing a perl interpreter),	891	L<AnyEvent::Fork::Early> (to avoid executing a perl interpreter),
876	L<AnyEvent::Fork::Template> (to create a process by forking the main	892	L<AnyEvent::Fork::Template> (to create a process by forking the main

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Comparing AnyEvent-Fork/Fork.pm (file contents): Revision 1.26 by root, Sat Apr 6 08:58:51 2013 UTC vs. Revision 1.37 by root, Sat Apr 6 20:06:39 2013 UTC

Diff Legend

Comparing AnyEvent-Fork/Fork.pm (file contents):
Revision 1.26 by root, Sat Apr 6 08:58:51 2013 UTC vs.
Revision 1.37 by root, Sat Apr 6 20:06:39 2013 UTC