Re: Postgres 7.4.7 hang in async_notify
От | Tom Lane |
---|---|
Тема | Re: Postgres 7.4.7 hang in async_notify |
Дата | |
Msg-id | 28071.1117746362@sss.pgh.pa.us обсуждение исходный текст |
Ответ на | Postgres 7.4.7 hang in async_notify (pgsql-bugs@counterstorm.com) |
Ответы |
Re: Postgres 7.4.7 hang in async_notify
(pgsql-bugs@counterstorm.com)
|
Список | pgsql-bugs |
pgsql-bugs@counterstorm.com writes: > We saw the problem with async_notify again (See thread with subject > "Postgres 7.4.6 hang in async_notify" in first message to this list > dated "Mon, 25 Apr 2005 15:42:35 -0400") in a production setting. I've applied a patch that (I think) will fix this. Attached is the 7.4-branch version of it. regards, tom lane Index: src/backend/libpq/be-secure.c =================================================================== RCS file: /cvsroot/pgsql/src/backend/libpq/be-secure.c,v retrieving revision 1.43.2.1 diff -c -r1.43.2.1 be-secure.c *** src/backend/libpq/be-secure.c 18 Dec 2003 22:49:34 -0000 1.43.2.1 --- src/backend/libpq/be-secure.c 2 Jun 2005 20:43:58 -0000 *************** *** 79,85 **** #include <sys/stat.h> #include <signal.h> #include <fcntl.h> - #include <errno.h> #include <ctype.h> #include <sys/socket.h> #include <unistd.h> --- 79,84 ---- *************** *** 97,102 **** --- 96,103 ---- #include "libpq/libpq.h" #include "miscadmin.h" + #include "tcop/tcopprot.h" + #ifdef USE_SSL static DH *load_dh_file(int keylength); *************** *** 301,308 **** --- 302,315 ---- } else #endif + { + prepare_for_client_read(); + n = recv(port->sock, ptr, len, 0); + client_read_ended(); + } + return n; } *************** *** 395,400 **** --- 402,474 ---- /* SSL specific code */ /* ------------------------------------------------------------ */ #ifdef USE_SSL + + /* + * Private substitute BIO: this wraps the SSL library's standard socket BIO + * so that we can enable and disable interrupts just while calling recv(). + * We cannot have interrupts occurring while the bulk of openssl runs, + * because it uses malloc() and possibly other non-reentrant libc facilities. + * + * As of openssl 0.9.7, we can use the reasonably clean method of interposing + * a wrapper around the standard socket BIO's sock_read() method. This relies + * on the fact that sock_read() doesn't call anything non-reentrant, in fact + * not much of anything at all except recv(). If this ever changes we'd + * probably need to duplicate the code of sock_read() in order to push the + * interrupt enable/disable down yet another level. + */ + + static bool my_bio_initialized = false; + static BIO_METHOD my_bio_methods; + static int (*std_sock_read) (BIO *h, char *buf, int size); + + static int + my_sock_read(BIO *h, char *buf, int size) + { + int res; + + prepare_for_client_read(); + + res = std_sock_read(h, buf, size); + + client_read_ended(); + + return res; + } + + static BIO_METHOD * + my_BIO_s_socket(void) + { + if (!my_bio_initialized) + { + memcpy(&my_bio_methods, BIO_s_socket(), sizeof(BIO_METHOD)); + std_sock_read = my_bio_methods.bread; + my_bio_methods.bread = my_sock_read; + my_bio_initialized = true; + } + return &my_bio_methods; + } + + /* This should exactly match openssl's SSL_set_fd except for using my BIO */ + static int + my_SSL_set_fd(SSL *s, int fd) + { + int ret=0; + BIO *bio=NULL; + + bio=BIO_new(my_BIO_s_socket()); + + if (bio == NULL) + { + SSLerr(SSL_F_SSL_SET_FD,ERR_R_BUF_LIB); + goto err; + } + BIO_set_fd(bio,fd,BIO_NOCLOSE); + SSL_set_bio(s,bio,bio); + ret=1; + err: + return(ret); + } + /* * Load precomputed DH parameters. * *************** *** 718,724 **** Assert(!port->peer); if (!(port->ssl = SSL_new(SSL_context)) || ! !SSL_set_fd(port->ssl, port->sock) || SSL_accept(port->ssl) <= 0) { ereport(COMMERROR, --- 792,798 ---- Assert(!port->peer); if (!(port->ssl = SSL_new(SSL_context)) || ! !my_SSL_set_fd(port->ssl, port->sock) || SSL_accept(port->ssl) <= 0) { ereport(COMMERROR, Index: src/backend/tcop/postgres.c =================================================================== RCS file: /cvsroot/pgsql/src/backend/tcop/postgres.c,v retrieving revision 1.375.2.2 diff -c -r1.375.2.2 postgres.c *** src/backend/tcop/postgres.c 26 Sep 2004 00:26:53 -0000 1.375.2.2 --- src/backend/tcop/postgres.c 2 Jun 2005 20:43:58 -0000 *************** *** 109,114 **** --- 109,121 ---- static bool xact_started = false; /* + * Flag to indicate that we are doing the outer loop's read-from-client, + * as opposed to any random read from client that might happen within + * commands like COPY FROM STDIN. + */ + static bool DoingCommandRead = false; + + /* * Flags to implement skip-till-Sync-after-error behavior for messages of * the extended query protocol. */ *************** *** 400,405 **** --- 407,456 ---- return result; } + /* + * prepare_for_client_read -- set up to possibly block on client input + * + * This must be called immediately before any low-level read from the + * client connection. It is necessary to do it at a sufficiently low level + * that there won't be any other operations except the read kernel call + * itself between this call and the subsequent client_read_ended() call. + * In particular there mustn't be use of malloc() or other potentially + * non-reentrant libc functions. This restriction makes it safe for us + * to allow interrupt service routines to execute nontrivial code while + * we are waiting for input. + */ + void + prepare_for_client_read(void) + { + if (DoingCommandRead) + { + /* Enable immediate processing of asynchronous signals */ + EnableNotifyInterrupt(); + + /* Allow "die" interrupt to be processed while waiting */ + ImmediateInterruptOK = true; + + /* And don't forget to detect one that already arrived */ + QueryCancelPending = false; + CHECK_FOR_INTERRUPTS(); + } + } + + /* + * client_read_ended -- get out of the client-input state + */ + void + client_read_ended(void) + { + if (DoingCommandRead) + { + ImmediateInterruptOK = false; + QueryCancelPending = false; /* forget any CANCEL signal */ + + DisableNotifyInterrupt(); + } + } + /* * Parse a query string and pass it through the rewriter. *************** *** 2706,2711 **** --- 2757,2763 ---- CritSectionCount = 0; /* should be unnecessary, but... */ disable_sig_alarm(true); QueryCancelPending = false; /* again in case timeout occurred */ + DoingCommandRead = false; DisableNotifyInterrupt(); debug_query_string = NULL; *************** *** 2814,2833 **** } /* ! * (2) deal with pending asynchronous NOTIFY from other backends, ! * and enable async.c's signal handler to execute NOTIFY directly. ! * Then set up other stuff needed before blocking for input. */ ! QueryCancelPending = false; /* forget any earlier CANCEL ! * signal */ ! ! EnableNotifyInterrupt(); ! ! /* Allow "die" interrupt to be processed while waiting */ ! ImmediateInterruptOK = true; ! /* and don't forget to detect one that already arrived */ ! QueryCancelPending = false; ! CHECK_FOR_INTERRUPTS(); /* * (3) read a command (loop blocks here) --- 2866,2878 ---- } /* ! * (2) Allow asynchronous signals to be executed immediately ! * if they come in while we are waiting for client input. ! * (This must be conditional since we don't want, say, reads on ! * behalf of COPY FROM STDIN doing the same thing.) */ ! QueryCancelPending = false; /* forget any earlier CANCEL signal */ ! DoingCommandRead = true; /* * (3) read a command (loop blocks here) *************** *** 2837,2846 **** /* * (4) disable async signal conditions again. */ ! ImmediateInterruptOK = false; ! QueryCancelPending = false; /* forget any CANCEL signal */ ! ! DisableNotifyInterrupt(); /* * (5) check for any other interesting events that happened while --- 2882,2888 ---- /* * (4) disable async signal conditions again. */ ! DoingCommandRead = false; /* * (5) check for any other interesting events that happened while Index: src/include/tcop/tcopprot.h =================================================================== RCS file: /cvsroot/pgsql/src/include/tcop/tcopprot.h,v retrieving revision 1.60 diff -c -r1.60 tcopprot.h *** src/include/tcop/tcopprot.h 4 Aug 2003 02:40:15 -0000 1.60 --- src/include/tcop/tcopprot.h 2 Jun 2005 20:43:58 -0000 *************** *** 49,54 **** --- 49,56 ---- extern void die(SIGNAL_ARGS); extern void quickdie(SIGNAL_ARGS); extern void authdie(SIGNAL_ARGS); + extern void prepare_for_client_read(void); + extern void client_read_ended(void); extern int PostgresMain(int argc, char *argv[], const char *username); extern void ResetUsage(void); extern void ShowUsage(const char *title);
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