diff options
| -rw-r--r-- | src/backend/postmaster/postmaster.c | 44 | ||||
| -rw-r--r-- | src/backend/utils/init/globals.c | 9 | ||||
| -rw-r--r-- | src/backend/utils/misc/guc.c | 30 | ||||
| -rw-r--r-- | src/include/postmaster/postmaster.h | 9 |
4 files changed, 52 insertions, 40 deletions
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c index 73bacd89bcc..fa5aeed31db 100644 --- a/src/backend/postmaster/postmaster.c +++ b/src/backend/postmaster/postmaster.c @@ -499,6 +499,7 @@ typedef struct bool redirection_done; bool IsBinaryUpgrade; int max_safe_fds; + int MaxBackends; #ifdef WIN32 HANDLE PostmasterHandle; HANDLE initial_signal_pipe; @@ -897,15 +898,14 @@ PostmasterMain(int argc, char *argv[]) process_shared_preload_libraries(); /* - * If loadable modules have added background workers, MaxBackends needs to - * be updated. Do so now by forcing a no-op update of max_connections. - * XXX This is a pretty ugly way to do it, but it doesn't seem worth - * introducing a new entry point in guc.c to do it in a cleaner fashion. + * Now that loadable modules have had their chance to register background + * workers, calculate MaxBackends. Add one for the autovacuum launcher. */ - if (GetNumShmemAttachedBgworkers() > 0) - SetConfigOption("max_connections", - GetConfigOption("max_connections", false, false), - PGC_POSTMASTER, PGC_S_OVERRIDE); + MaxBackends = MaxConnections + autovacuum_max_workers + 1 + + GetNumShmemAttachedBgworkers(); + /* internal error because the values were all checked previously */ + if (MaxBackends > MAX_BACKENDS) + elog(ERROR, "too many backends configured"); /* * Establish input sockets. @@ -5152,6 +5152,8 @@ RegisterBackgroundWorker(BackgroundWorker *worker) { RegisteredBgWorker *rw; int namelen = strlen(worker->bgw_name); + static int maxworkers; + static int numworkers = 0; #ifdef EXEC_BACKEND @@ -5162,6 +5164,11 @@ RegisterBackgroundWorker(BackgroundWorker *worker) static int BackgroundWorkerCookie = 1; #endif + /* initialize upper limit on first call */ + if (numworkers == 0) + maxworkers = MAX_BACKENDS - + (MaxConnections + autovacuum_max_workers + 1); + if (!IsUnderPostmaster) ereport(LOG, (errmsg("registering background worker: %s", worker->bgw_name))); @@ -5215,6 +5222,23 @@ RegisterBackgroundWorker(BackgroundWorker *worker) } /* + * Enforce maximum number of workers. Note this is overly restrictive: + * we could allow more non-shmem-connected workers, because these don't + * count towards the MAX_BACKENDS limit elsewhere. This doesn't really + * matter for practical purposes; several million processes would need to + * run on a single server. + */ + if (++numworkers > maxworkers) + { + ereport(LOG, + (errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED), + errmsg("too many background workers"), + errdetail("Up to %d background workers can be registered with the current settings.", + maxworkers))); + return; + } + + /* * Copy the registration data into the registered workers list. */ rw = malloc(sizeof(RegisteredBgWorker) + namelen + 1); @@ -5836,6 +5860,8 @@ save_backend_variables(BackendParameters *param, Port *port, param->IsBinaryUpgrade = IsBinaryUpgrade; param->max_safe_fds = max_safe_fds; + param->MaxBackends = MaxBackends; + #ifdef WIN32 param->PostmasterHandle = PostmasterHandle; if (!write_duplicated_handle(¶m->initial_signal_pipe, @@ -6061,6 +6087,8 @@ restore_backend_variables(BackendParameters *param, Port *port) IsBinaryUpgrade = param->IsBinaryUpgrade; max_safe_fds = param->max_safe_fds; + MaxBackends = param->MaxBackends; + #ifdef WIN32 PostmasterHandle = param->PostmasterHandle; pgwin32_initial_signal_pipe = param->initial_signal_pipe; diff --git a/src/backend/utils/init/globals.c b/src/backend/utils/init/globals.c index 00288530c07..f1f8b177f35 100644 --- a/src/backend/utils/init/globals.c +++ b/src/backend/utils/init/globals.c @@ -103,13 +103,14 @@ int work_mem = 1024; int maintenance_work_mem = 16384; /* - * Primary determinants of sizes of shared-memory structures. MaxBackends is - * MaxConnections + autovacuum_max_workers + 1 (it is computed by the GUC - * assign hooks for those variables): + * Primary determinants of sizes of shared-memory structures. + * + * MaxBackends is computed by PostmasterMain after modules have had a chance to + * register background workers. */ int NBuffers = 1000; -int MaxBackends = 100; int MaxConnections = 90; +int MaxBackends = 0; int VacuumCostPageHit = 1; /* GUC parameters for vacuum */ int VacuumCostPageMiss = 10; diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c index d91924cc234..ac5e4f3e48d 100644 --- a/src/backend/utils/misc/guc.c +++ b/src/backend/utils/misc/guc.c @@ -103,17 +103,6 @@ #define MAX_KILOBYTES (INT_MAX / 1024) #endif -/* - * Note: MAX_BACKENDS is limited to 2^23-1 because inval.c stores the - * backend ID as a 3-byte signed integer. Even if that limitation were - * removed, we still could not exceed INT_MAX/4 because some places compute - * 4*MaxBackends without any overflow check. This is rechecked in - * check_maxconnections, since MaxBackends is computed as MaxConnections - * plus the number of bgworkers plus autovacuum_max_workers plus one (for the - * autovacuum launcher). - */ -#define MAX_BACKENDS 0x7fffff - #define KB_PER_MB (1024) #define KB_PER_GB (1024*1024) @@ -199,9 +188,7 @@ static const char *show_tcp_keepalives_idle(void); static const char *show_tcp_keepalives_interval(void); static const char *show_tcp_keepalives_count(void); static bool check_maxconnections(int *newval, void **extra, GucSource source); -static void assign_maxconnections(int newval, void *extra); static bool check_autovacuum_max_workers(int *newval, void **extra, GucSource source); -static void assign_autovacuum_max_workers(int newval, void *extra); static bool check_effective_io_concurrency(int *newval, void **extra, GucSource source); static void assign_effective_io_concurrency(int newval, void *extra); static void assign_pgstat_temp_directory(const char *newval, void *extra); @@ -1615,7 +1602,7 @@ static struct config_int ConfigureNamesInt[] = }, &MaxConnections, 100, 1, MAX_BACKENDS, - check_maxconnections, assign_maxconnections, NULL + check_maxconnections, NULL, NULL }, { @@ -2290,7 +2277,7 @@ static struct config_int ConfigureNamesInt[] = }, &autovacuum_max_workers, 3, 1, MAX_BACKENDS, - check_autovacuum_max_workers, assign_autovacuum_max_workers, NULL + check_autovacuum_max_workers, NULL, NULL }, { @@ -8636,13 +8623,6 @@ check_maxconnections(int *newval, void **extra, GucSource source) return true; } -static void -assign_maxconnections(int newval, void *extra) -{ - MaxBackends = newval + autovacuum_max_workers + 1 + - GetNumShmemAttachedBgworkers(); -} - static bool check_autovacuum_max_workers(int *newval, void **extra, GucSource source) { @@ -8652,12 +8632,6 @@ check_autovacuum_max_workers(int *newval, void **extra, GucSource source) return true; } -static void -assign_autovacuum_max_workers(int newval, void *extra) -{ - MaxBackends = MaxConnections + newval + 1 + GetNumShmemAttachedBgworkers(); -} - static bool check_effective_io_concurrency(int *newval, void **extra, GucSource source) { diff --git a/src/include/postmaster/postmaster.h b/src/include/postmaster/postmaster.h index eaca868b008..8b2d5b913e3 100644 --- a/src/include/postmaster/postmaster.h +++ b/src/include/postmaster/postmaster.h @@ -61,4 +61,13 @@ extern Size ShmemBackendArraySize(void); extern void ShmemBackendArrayAllocation(void); #endif +/* + * Note: MAX_BACKENDS is limited to 2^23-1 because inval.c stores the + * backend ID as a 3-byte signed integer. Even if that limitation were + * removed, we still could not exceed INT_MAX/4 because some places compute + * 4*MaxBackends without any overflow check. This is rechecked in the relevant + * GUC check hooks and in RegisterBackgroundWorker(). + */ +#define MAX_BACKENDS 0x7fffff + #endif /* _POSTMASTER_H */ |