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50 50
51=head1 DESCRIPTION 51=head1 DESCRIPTION
52 52
53This module implements asynchronous I/O using whatever means your 53This module implements asynchronous I/O using whatever means your
54operating system supports. 54operating system supports.
55
56Asynchronous means that operations that can normally block your program
57(e.g. reading from disk) will be done asynchronously: the operation
58will still block, but you can do something else in the meantime. This
59is extremely useful for programs that need to stay interactive even
60when doing heavy I/O (GUI programs, high performance network servers
61etc.), but can also be used to easily do operations in parallel that are
62normally done sequentially, e.g. stat'ing many files, which is much faster
63on a RAID volume or over NFS when you do a number of stat operations
64concurrently.
65
66While this works on all types of file descriptors (for example sockets),
67using these functions on file descriptors that support nonblocking
68operation (again, sockets, pipes etc.) is very inefficient. Use an event
69loop for that (such as the L<Event|Event> module): IO::AIO will naturally
70fit into such an event loop itself.
55 71
56In this version, a number of threads are started that execute your 72In this version, a number of threads are started that execute your
57requests and signal their completion. You don't need thread support 73requests and signal their completion. You don't need thread support
58in perl, and the threads created by this module will not be visible 74in perl, and the threads created by this module will not be visible
59to perl. In the future, this module might make use of the native aio 75to perl. In the future, this module might make use of the native aio
60functions available on many operating systems. However, they are often 76functions available on many operating systems. However, they are often
61not well-supported or restricted (Linux doesn't allow them on normal 77not well-supported or restricted (GNU/Linux doesn't allow them on normal
62files currently, for example), and they would only support aio_read and 78files currently, for example), and they would only support aio_read and
63aio_write, so the remaining functionality would have to be implemented 79aio_write, so the remaining functionality would have to be implemented
64using threads anyway. 80using threads anyway.
65 81
66Although the module will work with in the presence of other (Perl-) 82Although the module will work with in the presence of other (Perl-)
67threads, it is currently not reentrant in any way, so use appropriate 83threads, it is currently not reentrant in any way, so use appropriate
68locking yourself, always call C<poll_cb> from within the same thread, or 84locking yourself, always call C<poll_cb> from within the same thread, or
69never call C<poll_cb> (or other C<aio_> functions) recursively. 85never call C<poll_cb> (or other C<aio_> functions) recursively.
70 86
87=head2 EXAMPLE
88
89This is a simple example that uses the Event module and loads
90F</etc/passwd> asynchronously:
91
92 use Fcntl;
93 use Event;
94 use IO::AIO;
95
96 # register the IO::AIO callback with Event
97 Event->io (fd => IO::AIO::poll_fileno,
98 poll => 'r',
99 cb => \&IO::AIO::poll_cb);
100
101 # queue the request to open /etc/passwd
102 aio_open "/etc/passwd", O_RDONLY, 0, sub {
103 my $fh = $_[0]
104 or die "error while opening: $!";
105
106 # stat'ing filehandles is generally non-blocking
107 my $size = -s $fh;
108
109 # queue a request to read the file
110 my $contents;
111 aio_read $fh, 0, $size, $contents, 0, sub {
112 $_[0] == $size
113 or die "short read: $!";
114
115 close $fh;
116
117 # file contents now in $contents
118 print $contents;
119
120 # exit event loop and program
121 Event::unloop;
122 };
123 };
124
125 # possibly queue up other requests, or open GUI windows,
126 # check for sockets etc. etc.
127
128 # process events as long as there are some:
129 Event::loop;
130
71=head1 REQUEST ANATOMY AND LIFETIME 131=head1 REQUEST ANATOMY AND LIFETIME
72 132
73Every C<aio_*> function creates a request. which is a C data structure not 133Every C<aio_*> function creates a request. which is a C data structure not
74directly visible to Perl. 134directly visible to Perl.
75 135
… …
116Request has reached the end of its lifetime and holds no resources anymore 176Request has reached the end of its lifetime and holds no resources anymore
117(except possibly for the Perl object, but its connection to the actual 177(except possibly for the Perl object, but its connection to the actual
118aio request is severed and calling its methods will either do nothing or 178aio request is severed and calling its methods will either do nothing or
119result in a runtime error). 179result in a runtime error).
120 180
181=back
182
121=cut 183=cut
122 184
123package IO::AIO; 185package IO::AIO;
124 186
125no warnings; 187no warnings;
126use strict 'vars'; 188use strict 'vars';
127 189
128use base 'Exporter'; 190use base 'Exporter';
129 191
130BEGIN { 192BEGIN {
131 our $VERSION = '2.0'; 193 our $VERSION = '2.1';
132 194
133 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat 195 our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
134 aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink 196 aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
135 aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move 197 aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move
136 aio_group aio_nop); 198 aio_copy aio_group aio_nop aio_mknod);
137 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice)); 199 our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
138 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush 200 our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
139 min_parallel max_parallel nreqs nready npending); 201 min_parallel max_parallel max_idle
202 nreqs nready npending nthreads
203 max_poll_time max_poll_reqs);
140 204
141 @IO::AIO::GRP::ISA = 'IO::AIO::REQ'; 205 @IO::AIO::GRP::ISA = 'IO::AIO::REQ';
142 206
143 require XSLoader; 207 require XSLoader;
144 XSLoader::load ("IO::AIO", $VERSION); 208 XSLoader::load ("IO::AIO", $VERSION);
145} 209}
146 210
147=head1 FUNCTIONS 211=head1 FUNCTIONS
148 212
149=head2 AIO FUNCTIONS 213=head2 AIO REQUEST FUNCTIONS
150 214
151All the C<aio_*> calls are more or less thin wrappers around the syscall 215All the C<aio_*> calls are more or less thin wrappers around the syscall
152with the same name (sans C<aio_>). The arguments are similar or identical, 216with the same name (sans C<aio_>). The arguments are similar or identical,
153and they all accept an additional (and optional) C<$callback> argument 217and they all accept an additional (and optional) C<$callback> argument
154which must be a code reference. This code reference will get called with 218which must be a code reference. This code reference will get called with
… …
157syscall has been executed asynchronously. 221syscall has been executed asynchronously.
158 222
159All functions expecting a filehandle keep a copy of the filehandle 223All functions expecting a filehandle keep a copy of the filehandle
160internally until the request has finished. 224internally until the request has finished.
161 225
162All requests return objects of type L<IO::AIO::REQ> that allow further 226All functions return request objects of type L<IO::AIO::REQ> that allow
163manipulation of those requests while they are in-flight. 227further manipulation of those requests while they are in-flight.
164 228
165The pathnames you pass to these routines I<must> be absolute and 229The pathnames you pass to these routines I<must> be absolute and
166encoded in byte form. The reason for the former is that at the time the 230encoded as octets. The reason for the former is that at the time the
167request is being executed, the current working directory could have 231request is being executed, the current working directory could have
168changed. Alternatively, you can make sure that you never change the 232changed. Alternatively, you can make sure that you never change the
169current working directory. 233current working directory anywhere in the program and then use relative
234paths.
170 235
171To encode pathnames to byte form, either make sure you either: a) 236To encode pathnames as octets, either make sure you either: a) always pass
172always pass in filenames you got from outside (command line, readdir 237in filenames you got from outside (command line, readdir etc.) without
173etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode 238tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
174your pathnames to the locale (or other) encoding in effect in the user 239your pathnames to the locale (or other) encoding in effect in the user
175environment, d) use Glib::filename_from_unicode on unicode filenames or e) 240environment, d) use Glib::filename_from_unicode on unicode filenames or e)
176use something else. 241use something else to ensure your scalar has the correct contents.
242
243This works, btw. independent of the internal UTF-8 bit, which IO::AIO
244handles correctly wether it is set or not.
177 245
178=over 4 246=over 4
179 247
180=item $prev_pri = aioreq_pri [$pri] 248=item $prev_pri = aioreq_pri [$pri]
181 249
… …
204 }; 272 };
205 273
206=item aioreq_nice $pri_adjust 274=item aioreq_nice $pri_adjust
207 275
208Similar to C<aioreq_pri>, but subtracts the given value from the current 276Similar to C<aioreq_pri>, but subtracts the given value from the current
209priority, so effects are cumulative. 277priority, so the effect is cumulative.
210 278
211=item aio_open $pathname, $flags, $mode, $callback->($fh) 279=item aio_open $pathname, $flags, $mode, $callback->($fh)
212 280
213Asynchronously open or create a file and call the callback with a newly 281Asynchronously open or create a file and call the callback with a newly
214created filehandle for the file. 282created filehandle for the file.
… …
264 332
265 aio_read $fh, 7, 15, $buffer, 0, sub { 333 aio_read $fh, 7, 15, $buffer, 0, sub {
266 $_[0] > 0 or die "read error: $!"; 334 $_[0] > 0 or die "read error: $!";
267 print "read $_[0] bytes: <$buffer>\n"; 335 print "read $_[0] bytes: <$buffer>\n";
268 }; 336 };
269
270=item aio_move $srcpath, $dstpath, $callback->($status)
271
272Try to move the I<file> (directories not supported as either source or
273destination) from C<$srcpath> to C<$dstpath> and call the callback with
274the C<0> (error) or C<-1> ok.
275
276This is a composite request that tries to rename(2) the file first. If
277rename files with C<EXDEV>, it creates the destination file with mode 0200
278and copies the contents of the source file into it using C<aio_sendfile>,
279followed by restoring atime, mtime, access mode and uid/gid, in that
280order, and unlinking the C<$srcpath>.
281
282If an error occurs, the partial destination file will be unlinked, if
283possible, except when setting atime, mtime, access mode and uid/gid, where
284errors are being ignored.
285
286=cut
287
288sub aio_move($$$) {
289 my ($src, $dst, $cb) = @_;
290
291 my $pri = aioreq_pri;
292 my $grp = aio_group $cb;
293
294 aioreq_pri $pri;
295 add $grp aio_rename $src, $dst, sub {
296 if ($_[0] && $! == EXDEV) {
297 aioreq_pri $pri;
298 add $grp aio_open $src, O_RDONLY, 0, sub {
299 if (my $src_fh = $_[0]) {
300 my @stat = stat $src_fh;
301
302 aioreq_pri $pri;
303 add $grp aio_open $dst, O_WRONLY, 0200, sub {
304 if (my $dst_fh = $_[0]) {
305 aioreq_pri $pri;
306 add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
307 close $src_fh;
308
309 if ($_[0] == $stat[7]) {
310 utime $stat[8], $stat[9], $dst;
311 chmod $stat[2] & 07777, $dst_fh;
312 chown $stat[4], $stat[5], $dst_fh;
313 close $dst_fh;
314
315 aioreq_pri $pri;
316 add $grp aio_unlink $src, sub {
317 $grp->result ($_[0]);
318 };
319 } else {
320 my $errno = $!;
321 aioreq_pri $pri;
322 add $grp aio_unlink $dst, sub {
323 $! = $errno;
324 $grp->result (-1);
325 };
326 }
327 };
328 } else {
329 $grp->result (-1);
330 }
331 },
332
333 } else {
334 $grp->result (-1);
335 }
336 };
337 } else {
338 $grp->result ($_[0]);
339 }
340 };
341
342 $grp
343}
344 337
345=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) 338=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
346 339
347Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts 340Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
348reading at byte offset C<$in_offset>, and starts writing at the current 341reading at byte offset C<$in_offset>, and starts writing at the current
… …
404=item aio_unlink $pathname, $callback->($status) 397=item aio_unlink $pathname, $callback->($status)
405 398
406Asynchronously unlink (delete) a file and call the callback with the 399Asynchronously unlink (delete) a file and call the callback with the
407result code. 400result code.
408 401
402=item aio_mknod $path, $mode, $dev, $callback->($status)
403
404[EXPERIMENTAL]
405
406Asynchronously create a device node (or fifo). See mknod(2).
407
408The only (POSIX-) portable way of calling this function is:
409
410 aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ...
411
409=item aio_link $srcpath, $dstpath, $callback->($status) 412=item aio_link $srcpath, $dstpath, $callback->($status)
410 413
411Asynchronously create a new link to the existing object at C<$srcpath> at 414Asynchronously create a new link to the existing object at C<$srcpath> at
412the path C<$dstpath> and call the callback with the result code. 415the path C<$dstpath> and call the callback with the result code.
413 416
… …
432directory (i.e. opendir + readdir + closedir). The entries will not be 435directory (i.e. opendir + readdir + closedir). The entries will not be
433sorted, and will B<NOT> include the C<.> and C<..> entries. 436sorted, and will B<NOT> include the C<.> and C<..> entries.
434 437
435The callback a single argument which is either C<undef> or an array-ref 438The callback a single argument which is either C<undef> or an array-ref
436with the filenames. 439with the filenames.
440
441=item aio_copy $srcpath, $dstpath, $callback->($status)
442
443Try to copy the I<file> (directories not supported as either source or
444destination) from C<$srcpath> to C<$dstpath> and call the callback with
445the C<0> (error) or C<-1> ok.
446
447This is a composite request that it creates the destination file with
448mode 0200 and copies the contents of the source file into it using
449C<aio_sendfile>, followed by restoring atime, mtime, access mode and
450uid/gid, in that order.
451
452If an error occurs, the partial destination file will be unlinked, if
453possible, except when setting atime, mtime, access mode and uid/gid, where
454errors are being ignored.
455
456=cut
457
458sub aio_copy($$;$) {
459 my ($src, $dst, $cb) = @_;
460
461 my $pri = aioreq_pri;
462 my $grp = aio_group $cb;
463
464 aioreq_pri $pri;
465 add $grp aio_open $src, O_RDONLY, 0, sub {
466 if (my $src_fh = $_[0]) {
467 my @stat = stat $src_fh;
468
469 aioreq_pri $pri;
470 add $grp aio_open $dst, O_CREAT | O_WRONLY | O_TRUNC, 0200, sub {
471 if (my $dst_fh = $_[0]) {
472 aioreq_pri $pri;
473 add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
474 if ($_[0] == $stat[7]) {
475 $grp->result (0);
476 close $src_fh;
477
478 # those should not normally block. should. should.
479 utime $stat[8], $stat[9], $dst;
480 chmod $stat[2] & 07777, $dst_fh;
481 chown $stat[4], $stat[5], $dst_fh;
482 close $dst_fh;
483 } else {
484 $grp->result (-1);
485 close $src_fh;
486 close $dst_fh;
487
488 aioreq $pri;
489 add $grp aio_unlink $dst;
490 }
491 };
492 } else {
493 $grp->result (-1);
494 }
495 },
496
497 } else {
498 $grp->result (-1);
499 }
500 };
501
502 $grp
503}
504
505=item aio_move $srcpath, $dstpath, $callback->($status)
506
507Try to move the I<file> (directories not supported as either source or
508destination) from C<$srcpath> to C<$dstpath> and call the callback with
509the C<0> (error) or C<-1> ok.
510
511This is a composite request that tries to rename(2) the file first. If
512rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
513that is successful, unlinking the C<$srcpath>.
514
515=cut
516
517sub aio_move($$;$) {
518 my ($src, $dst, $cb) = @_;
519
520 my $pri = aioreq_pri;
521 my $grp = aio_group $cb;
522
523 aioreq_pri $pri;
524 add $grp aio_rename $src, $dst, sub {
525 if ($_[0] && $! == EXDEV) {
526 aioreq_pri $pri;
527 add $grp aio_copy $src, $dst, sub {
528 $grp->result ($_[0]);
529
530 if (!$_[0]) {
531 aioreq_pri $pri;
532 add $grp aio_unlink $src;
533 }
534 };
535 } else {
536 $grp->result ($_[0]);
537 }
538 };
539
540 $grp
541}
437 542
438=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) 543=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
439 544
440Scans a directory (similar to C<aio_readdir>) but additionally tries to 545Scans a directory (similar to C<aio_readdir>) but additionally tries to
441efficiently separate the entries of directory C<$path> into two sets of 546efficiently separate the entries of directory C<$path> into two sets of
… …
794 899
795=back 900=back
796 901
797=head2 SUPPORT FUNCTIONS 902=head2 SUPPORT FUNCTIONS
798 903
904=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
905
799=over 4 906=over 4
800 907
801=item $fileno = IO::AIO::poll_fileno 908=item $fileno = IO::AIO::poll_fileno
802 909
803Return the I<request result pipe file descriptor>. This filehandle must be 910Return the I<request result pipe file descriptor>. This filehandle must be
… …
807 914
808See C<poll_cb> for an example. 915See C<poll_cb> for an example.
809 916
810=item IO::AIO::poll_cb 917=item IO::AIO::poll_cb
811 918
812Process all outstanding events on the result pipe. You have to call this 919Process some outstanding events on the result pipe. You have to call this
813regularly. Returns the number of events processed. Returns immediately 920regularly. Returns the number of events processed. Returns immediately
814when no events are outstanding. 921when no events are outstanding. The amount of events processed depends on
922the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
815 923
816If not all requests were processed for whatever reason, the filehandle 924If not all requests were processed for whatever reason, the filehandle
817will still be ready when C<poll_cb> returns. 925will still be ready when C<poll_cb> returns.
818 926
819Example: Install an Event watcher that automatically calls 927Example: Install an Event watcher that automatically calls
… …
821 929
822 Event->io (fd => IO::AIO::poll_fileno, 930 Event->io (fd => IO::AIO::poll_fileno,
823 poll => 'r', async => 1, 931 poll => 'r', async => 1,
824 cb => \&IO::AIO::poll_cb); 932 cb => \&IO::AIO::poll_cb);
825 933
826=item IO::AIO::poll_some $max_requests 934=item IO::AIO::max_poll_reqs $nreqs
827 935
828Similar to C<poll_cb>, but only processes up to C<$max_requests> requests 936=item IO::AIO::max_poll_time $seconds
829at a time.
830 937
831Useful if you want to ensure some level of interactiveness when perl is 938These set the maximum number of requests (default C<0>, meaning infinity)
832not fast enough to process all requests in time. 939that are being processed by C<IO::AIO::poll_cb> in one call, respectively
940the maximum amount of time (default C<0>, meaning infinity) spent in
941C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
942of time C<poll_cb> is allowed to use).
943
944Setting C<max_poll_time> to a non-zero value creates an overhead of one
945syscall per request processed, which is not normally a problem unless your
946callbacks are really really fast or your OS is really really slow (I am
947not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
948
949Setting these is useful if you want to ensure some level of
950interactiveness when perl is not fast enough to process all requests in
951time.
952
953For interactive programs, values such as C<0.01> to C<0.1> should be fine.
833 954
834Example: Install an Event watcher that automatically calls 955Example: Install an Event watcher that automatically calls
835IO::AIO::poll_some with low priority, to ensure that other parts of the 956IO::AIO::poll_cb with low priority, to ensure that other parts of the
836program get the CPU sometimes even under high AIO load. 957program get the CPU sometimes even under high AIO load.
837 958
959 # try not to spend much more than 0.1s in poll_cb
960 IO::AIO::max_poll_time 0.1;
961
962 # use a low priority so other tasks have priority
838 Event->io (fd => IO::AIO::poll_fileno, 963 Event->io (fd => IO::AIO::poll_fileno,
839 poll => 'r', nice => 1, 964 poll => 'r', nice => 1,
840 cb => sub { IO::AIO::poll_some 256 }); 965 cb => &IO::AIO::poll_cb);
841 966
842=item IO::AIO::poll_wait 967=item IO::AIO::poll_wait
843 968
844Wait till the result filehandle becomes ready for reading (simply does a 969Wait till the result filehandle becomes ready for reading (simply does a
845C<select> on the filehandle. This is useful if you want to synchronously wait 970C<select> on the filehandle. This is useful if you want to synchronously
846for some requests to finish). 971wait for some requests to finish).
847 972
848See C<nreqs> for an example. 973See C<nreqs> for an example.
849 974
975=item IO::AIO::poll
976
977Waits until some requests have been handled.
978
979Strictly equivalent to:
980
981 IO::AIO::poll_wait, IO::AIO::poll_cb
982 if IO::AIO::nreqs;
983
850=item IO::AIO::nreqs 984=item IO::AIO::flush
851 985
852Returns the number of requests currently in the ready, execute or pending 986Wait till all outstanding AIO requests have been handled.
853states (i.e. for which their callback has not been invoked yet).
854 987
855Example: wait till there are no outstanding requests anymore: 988Strictly equivalent to:
856 989
857 IO::AIO::poll_wait, IO::AIO::poll_cb 990 IO::AIO::poll_wait, IO::AIO::poll_cb
858 while IO::AIO::nreqs; 991 while IO::AIO::nreqs;
859 992
860=item IO::AIO::nready 993=head3 CONTROLLING THE NUMBER OF THREADS
861
862Returns the number of requests currently in the ready state (not yet
863executed).
864
865=item IO::AIO::npending
866
867Returns the number of requests currently in the pending state (executed,
868but not yet processed by poll_cb).
869
870=item IO::AIO::flush
871
872Wait till all outstanding AIO requests have been handled.
873
874Strictly equivalent to:
875
876 IO::AIO::poll_wait, IO::AIO::poll_cb
877 while IO::AIO::nreqs;
878
879=item IO::AIO::poll
880
881Waits until some requests have been handled.
882
883Strictly equivalent to:
884
885 IO::AIO::poll_wait, IO::AIO::poll_cb
886 if IO::AIO::nreqs;
887 994
888=item IO::AIO::min_parallel $nthreads 995=item IO::AIO::min_parallel $nthreads
889 996
890Set the minimum number of AIO threads to C<$nthreads>. The current 997Set the minimum number of AIO threads to C<$nthreads>. The current
891default is C<8>, which means eight asynchronous operations can execute 998default is C<8>, which means eight asynchronous operations can execute
892concurrently at any one time (the number of outstanding requests, 999concurrently at any one time (the number of outstanding requests,
893however, is unlimited). 1000however, is unlimited).
894 1001
895IO::AIO starts threads only on demand, when an AIO request is queued and 1002IO::AIO starts threads only on demand, when an AIO request is queued and
896no free thread exists. 1003no free thread exists. Please note that queueing up a hundred requests can
1004create demand for a hundred threads, even if it turns out that everything
1005is in the cache and could have been processed faster by a single thread.
897 1006
898It is recommended to keep the number of threads relatively low, as some 1007It is recommended to keep the number of threads relatively low, as some
899Linux kernel versions will scale negatively with the number of threads 1008Linux kernel versions will scale negatively with the number of threads
900(higher parallelity => MUCH higher latency). With current Linux 2.6 1009(higher parallelity => MUCH higher latency). With current Linux 2.6
901versions, 4-32 threads should be fine. 1010versions, 4-32 threads should be fine.
… …
915This module automatically runs C<max_parallel 0> at program end, to ensure 1024This module automatically runs C<max_parallel 0> at program end, to ensure
916that all threads are killed and that there are no outstanding requests. 1025that all threads are killed and that there are no outstanding requests.
917 1026
918Under normal circumstances you don't need to call this function. 1027Under normal circumstances you don't need to call this function.
919 1028
1029=item IO::AIO::max_idle $nthreads
1030
1031Limit the number of threads (default: 4) that are allowed to idle (i.e.,
1032threads that did not get a request to process within 10 seconds). That
1033means if a thread becomes idle while C<$nthreads> other threads are also
1034idle, it will free its resources and exit.
1035
1036This is useful when you allow a large number of threads (e.g. 100 or 1000)
1037to allow for extremely high load situations, but want to free resources
1038under normal circumstances (1000 threads can easily consume 30MB of RAM).
1039
1040The default is probably ok in most situations, especially if thread
1041creation is fast. If thread creation is very slow on your system you might
1042want to use larger values.
1043
920=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs 1044=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
921 1045
922This is a very bad function to use in interactive programs because it 1046This is a very bad function to use in interactive programs because it
923blocks, and a bad way to reduce concurrency because it is inexact: Better 1047blocks, and a bad way to reduce concurrency because it is inexact: Better
924use an C<aio_group> together with a feed callback. 1048use an C<aio_group> together with a feed callback.
… …
933 1057
934You can still queue as many requests as you want. Therefore, 1058You can still queue as many requests as you want. Therefore,
935C<max_oustsanding> is mainly useful in simple scripts (with low values) or 1059C<max_oustsanding> is mainly useful in simple scripts (with low values) or
936as a stop gap to shield against fatal memory overflow (with large values). 1060as a stop gap to shield against fatal memory overflow (with large values).
937 1061
1062=head3 STATISTICAL INFORMATION
1063
1064=item IO::AIO::nreqs
1065
1066Returns the number of requests currently in the ready, execute or pending
1067states (i.e. for which their callback has not been invoked yet).
1068
1069Example: wait till there are no outstanding requests anymore:
1070
1071 IO::AIO::poll_wait, IO::AIO::poll_cb
1072 while IO::AIO::nreqs;
1073
1074=item IO::AIO::nready
1075
1076Returns the number of requests currently in the ready state (not yet
1077executed).
1078
1079=item IO::AIO::npending
1080
1081Returns the number of requests currently in the pending state (executed,
1082but not yet processed by poll_cb).
1083
938=back 1084=back
939 1085
940=cut 1086=cut
941 1087
942# support function to convert a fd into a perl filehandle 1088# support function to convert a fd into a perl filehandle
… …
954 1100
955 *$sym 1101 *$sym
956} 1102}
957 1103
958min_parallel 8; 1104min_parallel 8;
1105
1106END {
1107 min_parallel 1;
1108 flush;
1109};
959 1110
9601; 11111;
961 1112
962=head2 FORK BEHAVIOUR 1113=head2 FORK BEHAVIOUR
963 1114

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