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

Comparing AnyEvent-Fork/Fork.pm (file contents):
Revision 1.27 by root, Sat Apr 6 09:05:50 2013 UTC vs.
Revision 1.38 by root, Sat Apr 6 20:07:30 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
…		…
314	=head1 THE C<AnyEvent::Fork> CLASS	320	=head1 THE C<AnyEvent::Fork> CLASS
315		321
316	This module exports nothing, and only implements a single class -	322	This module exports nothing, and only implements a single class -
317	C<AnyEvent::Fork>.	323	C<AnyEvent::Fork>.
318		324
319	There are two constructors that both create new processes - C<new> and	325	There are two class constructors that both create new processes - C<new>
320	C<new_exec>. The C<fork> method creates a new process by forking an	326	and C<new_exec>. The C<fork> method creates a new process by forking an
321	existing one and could be considered a third constructor.	327	existing one and could be considered a third constructor.
322		328
323	Most of the remaining methods deal with preparing the new process, by	329	Most of the remaining methods deal with preparing the new process, by
324	loading code, evaluating code and sending data to the new process. They	330	loading code, evaluating code and sending data to the new process. They
325	usually return the process object, so you can chain method calls.	331	usually return the process object, so you can chain method calls.
326		332
327	If a process object is destroyed before calling its C<run> method, then	333	If a process object is destroyed before calling its C<run> method, then
328	the process simply exits. After C<run> is called, all responsibility is	334	the process simply exits. After C<run> is called, all responsibility is
329	passed to the specified function.	335	passed to the specified function.
330		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.
		340
331	=over 4	341	=over 4
332		342
333	=cut	343	=cut
334		344
335	package AnyEvent::Fork;	345	package AnyEvent::Fork;
…		…
344	use IO::FDPass;	354	use IO::FDPass;
345		355
346	our $VERSION = 0.5;	356	our $VERSION = 0.5;
347		357
348	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
349
350	=item my $pool = new AnyEvent::Fork key => value...
351
352	Create a new process pool. The following named parameters are supported:
353		359
354	=over 4	360	=over 4
355		361
356	=back	362	=back
357		363
…		…
453	Create a new "empty" perl interpreter process and returns its process	459	Create a new "empty" perl interpreter process and returns its process
454	object for further manipulation.	460	object for further manipulation.
455		461
456	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
457	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
458	C<new_exec> and kept around for future calls.	464	C<new_exec> first and then stays around for future calls.
459
460	When the process object is destroyed, it will release the file handle
461	that connects it with the new process. When the new process has not yet
462	called C<run>, then the process will exit. Otherwise, what happens depends
463	entirely on the code that is executed.
464		465
465	=cut	466	=cut
466		467
467	sub new {	468	sub new {
468	my $class = shift;	469	my $class = shift;
…		…
558	}	559	}
559		560
560	=item $pid = $proc->pid	561	=item $pid = $proc->pid
561		562
562	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
563	process> running AnyEvent::Fork, and C<undef> otherwise.	564	process running AnyEvent::Fork>, and C<undef> otherwise.
564		565
565	Normally, only processes created via C<< AnyEvent::Fork->new_exec >> and	566	Normally, only processes created via C<< AnyEvent::Fork->new_exec >> and
566	L<AnyEvent::Fork::Template> are direct children, and you are responsible	567	L<AnyEvent::Fork::Template> are direct children, and you are responsible
567	to clean up their zombies when they die.	568	to clean up their zombies when they die.
568		569
569	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
570	AnyEvent::Fork.	571	AnyEvent::Fork itself.
571		572
572	=cut	573	=cut
573		574
574	sub pid {	575	sub pid {
575	$_[0][0]	576	$_[0][0]
…		…
586		587
587	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
588	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
589	will be reported to stderr and cause the process to exit.	590	will be reported to stderr and cause the process to exit.
590		591
591	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
592	"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
593	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
594	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.
595		597
596	Returns the process object for easy chaining of method calls.	598	Returns the process object for easy chaining of method calls.
597		599
598	=cut	600	=cut
599		601
…		…
625	=item $proc = $proc->send_fh ($handle, ...)	627	=item $proc = $proc->send_fh ($handle, ...)
626		628
627	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,
628	to prepare a call to C<run>.	630	to prepare a call to C<run>.
629		631
630	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
631	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
632	accomplished by simply not storing the file handles anywhere after passing	634	handles. This is most easily accomplished by simply not storing the file
633	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.
634		637
635	Returns the process object for easy chaining of method calls.	638	Returns the process object for easy chaining of method calls.
636		639
637	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
638	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.
…		…
654	}	657	}
655		658
656	=item $proc = $proc->send_arg ($string, ...)	659	=item $proc = $proc->send_arg ($string, ...)
657		660
658	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
659	C<run>. The strings can be any octet string.	662	C<run>. The strings can be any octet strings.
660		663
661	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
662	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
663	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
664	data.	667	data.
…		…
680	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
681	process. The function is called with the communication socket as first	684	process. The function is called with the communication socket as first
682	argument, followed by all file handles and string arguments sent earlier	685	argument, followed by all file handles and string arguments sent earlier
683	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.
684		687
		688	The process object becomes unusable on return from this function - any
		689	further method calls result in undefined behaviour.
		690
685	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
686	looked up in the main package.	692	looked up in the C<main> package.
687		693
688	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
689	process exits.	695	process exits.
690		696
691	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
692	been sent, the callback is invoked with the local communications socket	698	been sent, the callback is invoked with the local communications socket
693	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
694	like.	700	like.
695
696	The process object becomes unusable on return from this function - any
697	further method calls result in undefined behaviour.
698		701
699	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,
700	to save on kernel memory.	703	to save on kernel memory.
701		704
702	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
…		…
777	479 vfork+execs per second, using AnyEvent::Fork->new_exec	780	479 vfork+execs per second, using AnyEvent::Fork->new_exec
778		781
779	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
780	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?
781		784
782	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
783	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
784	introduced is canceled out.	787	overhead introduced is canceled out.
785		788
786	If the benchmark process grows, the normal fork becomes even slower:	789	If the benchmark process grows, the normal fork becomes even slower:
787		790
788	1340 new processes, manual fork in a 20MB process	791	1340 new processes, manual fork of a 20MB process
789	731 new processes, manual fork in a 200MB process	792	731 new processes, manual fork of a 200MB process
790	235 new processes, manual fork in a 2000MB process	793	235 new processes, manual fork of a 2000MB process
791		794
792	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
793	very bad conscience because of the extra overhead required to start new	796	conscience because of the extra overhead required to start new processes.
794	processes.
795		797
796	=head1 TYPICAL PROBLEMS	798	=head1 TYPICAL PROBLEMS
797		799
798	This section lists typical problems that remain. I hope by recognising	800	This section lists typical problems that remain. I hope by recognising
799	them, most can be avoided.	801	them, most can be avoided.
800		802
801	=over 4	803	=over 4
802		804
803	=item "leaked" file descriptors for exec'ed processes	805	=item leaked file descriptors for exec'ed processes
804		806
805	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
806	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
807	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
808	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.
…		…
828	libraries or the code that leaks those file descriptors.	830	libraries or the code that leaks those file descriptors.
829		831
830	Fortunately, most of these leaked descriptors do no harm, other than	832	Fortunately, most of these leaked descriptors do no harm, other than
831	sitting on some resources.	833	sitting on some resources.
832		834
833	=item "leaked" file descriptors for fork'ed processes	835	=item leaked file descriptors for fork'ed processes
834		836
835	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,
836	which closes file descriptors not marked for being inherited.	838	which closes file descriptors not marked for being inherited.
837		839
838	However, L<AnyEvent::Fork::Early> and L<AnyEvent::Fork::Template> offer	840	However, L<AnyEvent::Fork::Early> and L<AnyEvent::Fork::Template> offer
…		…
847		849
848	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
849	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
850	initialising them, for example, by calling C<init Gtk2> manually.	852	initialising them, for example, by calling C<init Gtk2> manually.
851		853
852	=item exit runs destructors	854	=item exiting calls object destructors
853		855
854	This only applies to users of Lc<AnyEvent::Fork:Early> and	856	This only applies to users of L<AnyEvent::Fork:Early> and
855	L<AnyEvent::Fork::Template>.	857	L<AnyEvent::Fork::Template>, or when initialiasing code creates objects
		858	that reference external resources.
856		859
857	When a process created by AnyEvent::Fork exits, it might do so by calling	860	When a process created by AnyEvent::Fork exits, it might do so by calling
858	exit, or simply letting perl reach the end of the program. At which point	861	exit, or simply letting perl reach the end of the program. At which point
859	Perl runs all destructors.	862	Perl runs all destructors.
860		863
…		…
879	to make it so, mostly due to the bloody broken perl that nobody seems to	882	to make it so, mostly due to the bloody broken perl that nobody seems to
880	care about. The fork emulation is a bad joke - I have yet to see something	883	care about. The fork emulation is a bad joke - I have yet to see something
881	useful that you can do with it without running into memory corruption	884	useful that you can do with it without running into memory corruption
882	issues or other braindamage. Hrrrr.	885	issues or other braindamage. Hrrrr.
883		886
884	Cygwin perl is not supported at the moment, as it should implement fd	887	Cygwin perl is not supported at the moment due to some hilarious
885	passing, but doesn't, and rolling my own is hard, as cygwin doesn't	888	shortcomings of its API - see L<IO::FDPoll> for more details.
886	support enough functionality to do it.
887		889
888	=head1 SEE ALSO	890	=head1 SEE ALSO
889		891
890	L<AnyEvent::Fork::Early> (to avoid executing a perl interpreter),	892	L<AnyEvent::Fork::Early> (to avoid executing a perl interpreter),
891	L<AnyEvent::Fork::Template> (to create a process by forking the main	893	L<AnyEvent::Fork::Template> (to create a process by forking the main

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Comparing AnyEvent-Fork/Fork.pm (file contents): Revision 1.27 by root, Sat Apr 6 09:05:50 2013 UTC vs. Revision 1.38 by root, Sat Apr 6 20:07:30 2013 UTC

Diff Legend

Comparing AnyEvent-Fork/Fork.pm (file contents):
Revision 1.27 by root, Sat Apr 6 09:05:50 2013 UTC vs.
Revision 1.38 by root, Sat Apr 6 20:07:30 2013 UTC