… | |
… | |
3 | BDB - Asynchronous Berkeley DB access |
3 | BDB - Asynchronous Berkeley DB access |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | use BDB; |
7 | use BDB; |
|
|
8 | |
|
|
9 | my $env = db_env_create; |
|
|
10 | |
|
|
11 | mkdir "bdtest", 0700; |
|
|
12 | db_env_open |
|
|
13 | $env, |
|
|
14 | "bdtest", |
|
|
15 | BDB::INIT_LOCK | BDB::INIT_LOG | BDB::INIT_MPOOL |
|
|
16 | | BDB::INIT_TXN | BDB::RECOVER | BDB::USE_ENVIRON | BDB::CREATE, |
|
|
17 | 0600; |
|
|
18 | |
|
|
19 | $env->set_flags (BDB::AUTO_COMMIT | BDB::TXN_NOSYNC, 1); |
|
|
20 | |
|
|
21 | my $db = db_create $env; |
|
|
22 | db_open $db, undef, "table", undef, BDB::BTREE, BDB::AUTO_COMMIT | BDB::CREATE |
|
|
23 | | BDB::READ_UNCOMMITTED, 0600; |
|
|
24 | db_put $db, undef, "key", "data", 0, sub { |
|
|
25 | db_del $db, undef, "key"; |
|
|
26 | }; |
|
|
27 | db_sync $db; |
|
|
28 | |
|
|
29 | # when you also use Coro, management is easy: |
|
|
30 | use Coro::BDB; |
|
|
31 | |
|
|
32 | # automatic result processing with AnyEvent: |
|
|
33 | our $FH; open $FH, "<&=" . BDB::poll_fileno; |
|
|
34 | our $WATCHER = AnyEvent->io (fh => $FH, poll => 'r', cb => \&BDB::poll_cb); |
|
|
35 | |
|
|
36 | # automatic result processing with EV: |
|
|
37 | my $WATCHER = EV::io BDB::poll_fileno, EV::READ, \&BDB::poll_cb; |
|
|
38 | |
|
|
39 | # with Glib: |
|
|
40 | add_watch Glib::IO BDB::poll_fileno, |
|
|
41 | in => sub { BDB::poll_cb; 1 }; |
|
|
42 | |
|
|
43 | # or simply flush manually |
|
|
44 | BDB::flush; |
|
|
45 | |
8 | |
46 | |
9 | =head1 DESCRIPTION |
47 | =head1 DESCRIPTION |
10 | |
48 | |
11 | See the BerkeleyDB documentation (L<http://www.oracle.com/technology/documentation/berkeley-db/db/index.html>). |
49 | See the BerkeleyDB documentation (L<http://www.oracle.com/technology/documentation/berkeley-db/db/index.html>). |
12 | The BDB API is very similar to the C API (the translation has been very faithful). |
50 | The BDB API is very similar to the C API (the translation has been very faithful). |
… | |
… | |
72 | use strict 'vars'; |
110 | use strict 'vars'; |
73 | |
111 | |
74 | use base 'Exporter'; |
112 | use base 'Exporter'; |
75 | |
113 | |
76 | BEGIN { |
114 | BEGIN { |
77 | our $VERSION = '1.0'; |
115 | our $VERSION = '1.45'; |
78 | |
116 | |
79 | our @BDB_REQ = qw( |
117 | our @BDB_REQ = qw( |
80 | db_env_open db_env_close db_env_txn_checkpoint db_env_lock_detect |
118 | db_env_open db_env_close db_env_txn_checkpoint db_env_lock_detect |
81 | db_env_memp_sync db_env_memp_trickle |
119 | db_env_memp_sync db_env_memp_trickle |
82 | db_open db_close db_compact db_sync db_put db_get db_pget db_del db_key_range |
120 | db_open db_close db_compact db_sync db_upgrade |
|
|
121 | db_put db_get db_pget db_del db_key_range |
83 | db_txn_commit db_txn_abort |
122 | db_txn_commit db_txn_abort db_txn_finish |
84 | db_c_close db_c_count db_c_put db_c_get db_c_pget db_c_del |
123 | db_c_close db_c_count db_c_put db_c_get db_c_pget db_c_del |
85 | db_sequence_open db_sequence_close |
124 | db_sequence_open db_sequence_close |
86 | db_sequence_get db_sequence_remove |
125 | db_sequence_get db_sequence_remove |
87 | ); |
126 | ); |
88 | our @EXPORT = (@BDB_REQ, qw(dbreq_pri dbreq_nice db_env_create db_create)); |
127 | our @EXPORT = (@BDB_REQ, qw(dbreq_pri dbreq_nice db_env_create db_create)); |
… | |
… | |
95 | |
134 | |
96 | require XSLoader; |
135 | require XSLoader; |
97 | XSLoader::load ("BDB", $VERSION); |
136 | XSLoader::load ("BDB", $VERSION); |
98 | } |
137 | } |
99 | |
138 | |
|
|
139 | =head2 WIN32 FILENAMES/DATABASE NAME MESS |
|
|
140 | |
|
|
141 | Perl on Win32 supports only ASCII filenames (the reason is that it abuses |
|
|
142 | an internal flag to store wether a filename is Unicode or ANSI, but that |
|
|
143 | flag is used for somethign else in the perl core, so there is no way to |
|
|
144 | detect wether a filename is ANSI or Unicode-encoded). The BDB module |
|
|
145 | tries to work around this issue by assuming that the filename is an ANSI |
|
|
146 | filename and BDB was built for unicode support. |
|
|
147 | |
100 | =head2 BERKELEYDB FUNCTIONS |
148 | =head2 BERKELEYDB FUNCTIONS |
101 | |
149 | |
102 | All of these are functions. The create functions simply return a new |
150 | All of these are functions. The create functions simply return a new |
103 | object and never block. All the remaining functions all take an optional |
151 | object and never block. All the remaining functions take an optional |
104 | callback as last argument. If it is missing, then the fucntion will be |
152 | callback as last argument. If it is missing, then the function will be |
105 | executed synchronously. |
153 | executed synchronously. In both cases, C<$!> will reflect the return value |
|
|
154 | of the function. |
106 | |
155 | |
107 | BDB functions that cannot block (mostly functions that manipulate |
156 | BDB functions that cannot block (mostly functions that manipulate |
108 | settings) are method calls on the relevant objects, so the rule of thumb |
157 | settings) are method calls on the relevant objects, so the rule of thumb |
109 | is: if its a method, its not blocking, if its a function, it takes a |
158 | is: if it's a method, it's not blocking, if it's a function, it takes a |
110 | callback as last argument. |
159 | callback as last argument. |
111 | |
160 | |
112 | In the following, C<$int> signifies an integer return value, |
161 | In the following, C<$int> signifies an integer return value, |
113 | C<octetstring> is a "binary string" (i.e. a perl string with no character |
162 | C<octetstring> is a "binary string" (i.e. a perl string with no character |
114 | indices >255), C<U32> is an unsigned 32 bit integer, C<int> is some |
163 | indices >255), C<U32> is an unsigned 32 bit integer, C<int> is some |
… | |
… | |
145 | |
194 | |
146 | db_open (DB *db, DB_TXN_ornull *txnid, octetstring file, octetstring database, int type, U32 flags, int mode, SV *callback = &PL_sv_undef) |
195 | db_open (DB *db, DB_TXN_ornull *txnid, octetstring file, octetstring database, int type, U32 flags, int mode, SV *callback = &PL_sv_undef) |
147 | flags: AUTO_COMMIT CREATE EXCL MULTIVERSION NOMMAP RDONLY READ_UNCOMMITTED THREAD TRUNCATE |
196 | flags: AUTO_COMMIT CREATE EXCL MULTIVERSION NOMMAP RDONLY READ_UNCOMMITTED THREAD TRUNCATE |
148 | db_close (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef) |
197 | db_close (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef) |
149 | flags: DB_NOSYNC |
198 | flags: DB_NOSYNC |
|
|
199 | db_upgrade (DB *db, octetstring file, U32 flags = 0, SV *callback = &PL_sv_undef) |
150 | db_compact (DB *db, DB_TXN_ornull *txn = 0, SV *start = 0, SV *stop = 0, SV *unused1 = 0, U32 flags = DB_FREE_SPACE, SV *unused2 = 0, SV *callback = &PL_sv_undef) |
200 | db_compact (DB *db, DB_TXN_ornull *txn = 0, SV *start = 0, SV *stop = 0, SV *unused1 = 0, U32 flags = DB_FREE_SPACE, SV *unused2 = 0, SV *callback = &PL_sv_undef) |
151 | flags: FREELIST_ONLY FREE_SPACE |
201 | flags: FREELIST_ONLY FREE_SPACE |
152 | db_sync (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef) |
202 | db_sync (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef) |
153 | db_key_range (DB *db, DB_TXN_ornull *txn, SV *key, SV *key_range, U32 flags = 0, SV *callback = &PL_sv_undef) |
203 | db_key_range (DB *db, DB_TXN_ornull *txn, SV *key, SV *key_range, U32 flags = 0, SV *callback = &PL_sv_undef) |
154 | db_put (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) |
204 | db_put (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef) |
… | |
… | |
177 | db_sequence_get (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, int delta, SV *seq_value, U32 flags = DB_TXN_NOSYNC, SV *callback = &PL_sv_undef) |
227 | db_sequence_get (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, int delta, SV *seq_value, U32 flags = DB_TXN_NOSYNC, SV *callback = &PL_sv_undef) |
178 | flags: TXN_NOSYNC |
228 | flags: TXN_NOSYNC |
179 | db_sequence_remove (DB_SEQUENCE *seq, DB_TXN_ornull *txnid = 0, U32 flags = 0, SV *callback = &PL_sv_undef) |
229 | db_sequence_remove (DB_SEQUENCE *seq, DB_TXN_ornull *txnid = 0, U32 flags = 0, SV *callback = &PL_sv_undef) |
180 | flags: TXN_NOSYNC |
230 | flags: TXN_NOSYNC |
181 | |
231 | |
|
|
232 | =head4 db_txn_finish (DB_TXN *txn, U32 flags = 0, SV *callback = &PL_sv_undef) |
|
|
233 | |
|
|
234 | This is not actually a Berkeley DB function but a BDB module |
|
|
235 | extension. The background for this exytension is: It is very annoying to |
|
|
236 | have to check every single BDB function for error returns and provide a |
|
|
237 | codepath out of your transaction. While the BDB module still makes this |
|
|
238 | possible, it contains the following extensions: |
|
|
239 | |
|
|
240 | When a transaction-protected function returns any operating system |
|
|
241 | error (errno > 0), BDB will set the C<TXN_DEADLOCK> flag on the |
|
|
242 | transaction. This flag is also set by Berkeley DB functions themselves |
|
|
243 | when an operation fails with LOCK_DEADLOCK, and it causes all further |
|
|
244 | operations on that transaction (including C<db_txn_commit>) to fail. |
|
|
245 | |
|
|
246 | The C<db_txn_finish> request will look at this flag, and, if it is set, |
|
|
247 | will automatically call C<db_txn_abort> (setting errno to C<LOCK_DEADLOCK> |
|
|
248 | if it isn't set to something else yet). If it isn't set, it will call |
|
|
249 | C<db_txn_commit> and return the error normally. |
|
|
250 | |
|
|
251 | How to use this? Easy: just write your transaction normally: |
|
|
252 | |
|
|
253 | my $txn = $db_env->txn_begin; |
|
|
254 | db_get $db, $txn, "key", my $data; |
|
|
255 | db_put $db, $txn, "key", $data + 1 unless $! == BDB::NOTFOUND; |
|
|
256 | db_txn_finish $txn; |
|
|
257 | die "transaction failed" if $!; |
|
|
258 | |
|
|
259 | That is, handle only the expected errors. If something unexpected happens |
|
|
260 | (EIO, LOCK_NOTGRANTED or a deadlock in either db_get or db_put), then the remaining |
|
|
261 | requests (db_put in this case) will simply be skipped (they will fail with |
|
|
262 | LOCK_DEADLOCK) and the transaction will be aborted. |
|
|
263 | |
|
|
264 | You can use the C<< $txn->failed >> method to check wether a transaction |
|
|
265 | has failed in this way and abort further processing (excluding |
|
|
266 | C<db_txn_finish>). |
|
|
267 | |
182 | =head3 DB_ENV/database environment methods |
268 | =head3 DB_ENV/database environment methods |
183 | |
269 | |
184 | Methods available on DB_ENV/$env handles: |
270 | Methods available on DB_ENV/$env handles: |
185 | |
271 | |
186 | DESTROY (DB_ENV_ornull *env) |
272 | DESTROY (DB_ENV_ornull *env) |
… | |
… | |
196 | $int = $env->set_flags (U32 flags, int onoff) |
282 | $int = $env->set_flags (U32 flags, int onoff) |
197 | $env->set_errfile (FILE *errfile = 0) |
283 | $env->set_errfile (FILE *errfile = 0) |
198 | $env->set_msgfile (FILE *msgfile = 0) |
284 | $env->set_msgfile (FILE *msgfile = 0) |
199 | $int = $env->set_verbose (U32 which, int onoff = 1) |
285 | $int = $env->set_verbose (U32 which, int onoff = 1) |
200 | $int = $env->set_encrypt (const char *password, U32 flags = 0) |
286 | $int = $env->set_encrypt (const char *password, U32 flags = 0) |
201 | $int = $env->set_timeout (NV timeout, U32 flags) |
287 | $int = $env->set_timeout (NV timeout_seconds, U32 flags = SET_TXN_TIMEOUT) |
202 | $int = $env->set_mp_max_openfd (int maxopenfd); |
288 | $int = $env->set_mp_max_openfd (int maxopenfd); |
203 | $int = $env->set_mp_max_write (int maxwrite, int maxwrite_sleep); |
289 | $int = $env->set_mp_max_write (int maxwrite, int maxwrite_sleep); |
204 | $int = $env->set_mp_mmapsize (int mmapsize_mb) |
290 | $int = $env->set_mp_mmapsize (int mmapsize_mb) |
205 | $int = $env->set_lk_detect (U32 detect = DB_LOCK_DEFAULT) |
291 | $int = $env->set_lk_detect (U32 detect = DB_LOCK_DEFAULT) |
206 | $int = $env->set_lk_max_lockers (U32 max) |
292 | $int = $env->set_lk_max_lockers (U32 max) |
207 | $int = $env->set_lk_max_locks (U32 max) |
293 | $int = $env->set_lk_max_locks (U32 max) |
208 | $int = $env->set_lk_max_objects (U32 max) |
294 | $int = $env->set_lk_max_objects (U32 max) |
209 | $int = $env->set_lg_bsize (U32 max) |
295 | $int = $env->set_lg_bsize (U32 max) |
210 | $int = $env->set_lg_max (U32 max) |
296 | $int = $env->set_lg_max (U32 max) |
|
|
297 | $int = $env->mutex_set_increment (U32 increment) |
|
|
298 | $int = $env->mutex_set_tas_spins (U32 tas_spins) |
|
|
299 | $int = $env->mutex_set_max (U32 max) |
|
|
300 | $int = $env->mutex_set_align (U32 align) |
211 | |
301 | |
212 | $txn = $env->txn_begin (DB_TXN_ornull *parent = 0, U32 flags = 0) |
302 | $txn = $env->txn_begin (DB_TXN_ornull *parent = 0, U32 flags = 0) |
213 | flags: READ_COMMITTED READ_UNCOMMITTED TXN_NOSYNC TXN_NOWAIT TXN_SNAPSHOT TXN_SYNC TXN_WAIT TXN_WRITE_NOSYNC |
303 | flags: READ_COMMITTED READ_UNCOMMITTED TXN_NOSYNC TXN_NOWAIT TXN_SNAPSHOT TXN_SYNC TXN_WAIT TXN_WRITE_NOSYNC |
214 | |
304 | |
215 | =head4 Example: |
305 | =head4 Example: |
… | |
… | |
294 | DESTROY (DB_TXN_ornull *txn) |
384 | DESTROY (DB_TXN_ornull *txn) |
295 | CODE: |
385 | CODE: |
296 | if (txn) |
386 | if (txn) |
297 | txn->abort (txn); |
387 | txn->abort (txn); |
298 | |
388 | |
299 | $int = $txn->set_timeout (NV timeout, U32 flags) |
389 | $int = $txn->set_timeout (NV timeout_seconds, U32 flags = SET_TXN_TIMEOUT) |
300 | flags: SET_LOCK_TIMEOUT SET_TXN_TIMEOUT |
390 | flags: SET_LOCK_TIMEOUT SET_TXN_TIMEOUT |
|
|
391 | |
|
|
392 | $bool = $txn->failed |
|
|
393 | # see db_txn_finish documentation, above |
301 | |
394 | |
302 | |
395 | |
303 | =head3 DBC/cursor methods |
396 | =head3 DBC/cursor methods |
304 | |
397 | |
305 | Methods available on DBC/$dbc handles: |
398 | Methods available on DBC/$dbc handles: |
306 | |
399 | |
307 | DESTROY (DBC_ornull *dbc) |
400 | DESTROY (DBC_ornull *dbc) |
308 | CODE: |
401 | CODE: |
309 | if (dbc) |
402 | if (dbc) |
310 | dbc->c_close (dbc); |
403 | dbc->c_close (dbc); |
|
|
404 | |
|
|
405 | $int = $cursor->set_priority ($priority = PRIORITY_*) |
311 | |
406 | |
312 | =head4 Example: |
407 | =head4 Example: |
313 | |
408 | |
314 | my $c = $db->cursor; |
409 | my $c = $db->cursor; |
315 | |
410 | |
… | |
… | |
349 | |
444 | |
350 | =head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION |
445 | =head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION |
351 | |
446 | |
352 | =over 4 |
447 | =over 4 |
353 | |
448 | |
|
|
449 | =item $msg = BDB::strerror [$errno] |
|
|
450 | |
|
|
451 | Returns the string corresponding to the given errno value. If no argument |
|
|
452 | is given, use C<$!>. |
|
|
453 | |
|
|
454 | Note that the BDB module also patches the C<$!> variable directly, so you |
|
|
455 | should be able to get a bdb error string by simply stringifying C<$!>. |
|
|
456 | |
354 | =item $fileno = BDB::poll_fileno |
457 | =item $fileno = BDB::poll_fileno |
355 | |
458 | |
356 | Return the I<request result pipe file descriptor>. This filehandle must be |
459 | Return the I<request result pipe file descriptor>. This filehandle must be |
357 | polled for reading by some mechanism outside this module (e.g. Event or |
460 | polled for reading by some mechanism outside this module (e.g. Event or |
358 | select, see below or the SYNOPSIS). If the pipe becomes readable you have |
461 | select, see below or the SYNOPSIS). If the pipe becomes readable you have |
… | |
… | |
396 | interactiveness when perl is not fast enough to process all requests in |
499 | interactiveness when perl is not fast enough to process all requests in |
397 | time. |
500 | time. |
398 | |
501 | |
399 | For interactive programs, values such as C<0.01> to C<0.1> should be fine. |
502 | For interactive programs, values such as C<0.01> to C<0.1> should be fine. |
400 | |
503 | |
401 | Example: Install an Event watcher that automatically calls |
504 | Example: Install an EV watcher that automatically calls |
402 | BDB::poll_cb with low priority, to ensure that other parts of the |
505 | BDB::poll_cb with low priority, to ensure that other parts of the |
403 | program get the CPU sometimes even under high AIO load. |
506 | program get the CPU sometimes even under high load. |
404 | |
507 | |
405 | # try not to spend much more than 0.1s in poll_cb |
508 | # try not to spend much more than 0.1s in poll_cb |
406 | BDB::max_poll_time 0.1; |
509 | BDB::max_poll_time 0.1; |
407 | |
510 | |
408 | # use a low priority so other tasks have priority |
511 | my $bdb_poll = EV::io BDB::poll_fileno, EV::READ, \&BDB::poll_cb); |
409 | Event->io (fd => BDB::poll_fileno, |
|
|
410 | poll => 'r', nice => 1, |
|
|
411 | cb => &BDB::poll_cb); |
|
|
412 | |
512 | |
413 | =item BDB::poll_wait |
513 | =item BDB::poll_wait |
414 | |
514 | |
415 | If there are any outstanding requests and none of them in the result |
515 | If there are any outstanding requests and none of them in the result |
416 | phase, wait till the result filehandle becomes ready for reading (simply |
516 | phase, wait till the result filehandle becomes ready for reading (simply |
… | |
… | |
428 | |
528 | |
429 | BDB::poll_wait, BDB::poll_cb |
529 | BDB::poll_wait, BDB::poll_cb |
430 | |
530 | |
431 | =item BDB::flush |
531 | =item BDB::flush |
432 | |
532 | |
433 | Wait till all outstanding AIO requests have been handled. |
533 | Wait till all outstanding BDB requests have been handled. |
434 | |
534 | |
435 | Strictly equivalent to: |
535 | Strictly equivalent to: |
436 | |
536 | |
437 | BDB::poll_wait, BDB::poll_cb |
537 | BDB::poll_wait, BDB::poll_cb |
438 | while BDB::nreqs; |
538 | while BDB::nreqs; |
… | |
… | |
443 | |
543 | |
444 | =over 4 |
544 | =over 4 |
445 | |
545 | |
446 | =item BDB::min_parallel $nthreads |
546 | =item BDB::min_parallel $nthreads |
447 | |
547 | |
448 | Set the minimum number of AIO threads to C<$nthreads>. The current |
548 | Set the minimum number of BDB threads to C<$nthreads>. The current |
449 | default is C<8>, which means eight asynchronous operations can execute |
549 | default is C<8>, which means eight asynchronous operations can execute |
450 | concurrently at any one time (the number of outstanding requests, |
550 | concurrently at any one time (the number of outstanding requests, |
451 | however, is unlimited). |
551 | however, is unlimited). |
452 | |
552 | |
453 | BDB starts threads only on demand, when an AIO request is queued and |
553 | BDB starts threads only on demand, when an BDB request is queued and |
454 | no free thread exists. Please note that queueing up a hundred requests can |
554 | no free thread exists. Please note that queueing up a hundred requests can |
455 | create demand for a hundred threads, even if it turns out that everything |
555 | create demand for a hundred threads, even if it turns out that everything |
456 | is in the cache and could have been processed faster by a single thread. |
556 | is in the cache and could have been processed faster by a single thread. |
457 | |
557 | |
458 | It is recommended to keep the number of threads relatively low, as some |
558 | It is recommended to keep the number of threads relatively low, as some |
… | |
… | |
463 | Under most circumstances you don't need to call this function, as the |
563 | Under most circumstances you don't need to call this function, as the |
464 | module selects a default that is suitable for low to moderate load. |
564 | module selects a default that is suitable for low to moderate load. |
465 | |
565 | |
466 | =item BDB::max_parallel $nthreads |
566 | =item BDB::max_parallel $nthreads |
467 | |
567 | |
468 | Sets the maximum number of AIO threads to C<$nthreads>. If more than the |
568 | Sets the maximum number of BDB threads to C<$nthreads>. If more than the |
469 | specified number of threads are currently running, this function kills |
569 | specified number of threads are currently running, this function kills |
470 | them. This function blocks until the limit is reached. |
570 | them. This function blocks until the limit is reached. |
471 | |
571 | |
472 | While C<$nthreads> are zero, aio requests get queued but not executed |
572 | While C<$nthreads> are zero, aio requests get queued but not executed |
473 | until the number of threads has been increased again. |
573 | until the number of threads has been increased again. |
… | |
… | |
576 | |
676 | |
577 | =head2 FORK BEHAVIOUR |
677 | =head2 FORK BEHAVIOUR |
578 | |
678 | |
579 | This module should do "the right thing" when the process using it forks: |
679 | This module should do "the right thing" when the process using it forks: |
580 | |
680 | |
581 | Before the fork, IO::AIO enters a quiescent state where no requests |
681 | Before the fork, BDB enters a quiescent state where no requests |
582 | can be added in other threads and no results will be processed. After |
682 | can be added in other threads and no results will be processed. After |
583 | the fork the parent simply leaves the quiescent state and continues |
683 | the fork the parent simply leaves the quiescent state and continues |
584 | request/result processing, while the child frees the request/result queue |
684 | request/result processing, while the child frees the request/result queue |
585 | (so that the requests started before the fork will only be handled in the |
685 | (so that the requests started before the fork will only be handled in the |
586 | parent). Threads will be started on demand until the limit set in the |
686 | parent). Threads will be started on demand until the limit set in the |
587 | parent process has been reached again. |
687 | parent process has been reached again. |
588 | |
688 | |
589 | In short: the parent will, after a short pause, continue as if fork had |
689 | In short: the parent will, after a short pause, continue as if fork had |
590 | not been called, while the child will act as if IO::AIO has not been used |
690 | not been called, while the child will act as if BDB has not been used |
591 | yet. |
691 | yet. |
|
|
692 | |
|
|
693 | Win32 note: there is no fork on win32, and perls emulation of it is too |
|
|
694 | broken to be supported, so do not use BDB in a windows pseudo-fork, better |
|
|
695 | yet, switch to a more capable platform. |
592 | |
696 | |
593 | =head2 MEMORY USAGE |
697 | =head2 MEMORY USAGE |
594 | |
698 | |
595 | Per-request usage: |
699 | Per-request usage: |
596 | |
700 | |
… | |
… | |
609 | temporary buffers, and each thread requires a stack and other data |
713 | temporary buffers, and each thread requires a stack and other data |
610 | structures (usually around 16k-128k, depending on the OS). |
714 | structures (usually around 16k-128k, depending on the OS). |
611 | |
715 | |
612 | =head1 KNOWN BUGS |
716 | =head1 KNOWN BUGS |
613 | |
717 | |
614 | Known bugs will be fixed in the next release. |
718 | Known bugs will be fixed in the next release, except: |
|
|
719 | |
|
|
720 | If you use a transaction in any request, and the request returns |
|
|
721 | with an operating system error or DB_LOCK_NOTGRANTED, the internal |
|
|
722 | TXN_DEADLOCK flag will be set on the transaction. See C<db_txn_finish>, |
|
|
723 | above. |
615 | |
724 | |
616 | =head1 SEE ALSO |
725 | =head1 SEE ALSO |
617 | |
726 | |
618 | L<Coro::AIO>. |
727 | L<Coro::BDB>, L<IO::AIO>. |
619 | |
728 | |
620 | =head1 AUTHOR |
729 | =head1 AUTHOR |
621 | |
730 | |
622 | Marc Lehmann <schmorp@schmorp.de> |
731 | Marc Lehmann <schmorp@schmorp.de> |
623 | http://home.schmorp.de/ |
732 | http://home.schmorp.de/ |