*** a/src/backend/postmaster/postmaster.c --- b/src/backend/postmaster/postmaster.c *************** *** 499,504 **** typedef struct --- 499,505 ---- bool redirection_done; bool IsBinaryUpgrade; int max_safe_fds; + int MaxBackends; #ifdef WIN32 HANDLE PostmasterHandle; HANDLE initial_signal_pipe; *************** *** 897,911 **** 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. */ ! if (GetNumShmemAttachedBgworkers() > 0) ! SetConfigOption("max_connections", ! GetConfigOption("max_connections", false, false), ! PGC_POSTMASTER, PGC_S_OVERRIDE); /* * Establish input sockets. --- 898,908 ---- process_shared_preload_libraries(); /* ! * Now that loadable modules have had their chance to register background ! * workers, calculate MaxBackends. Add one for the autovacuum launcher. */ ! MaxBackends = MaxConnections + autovacuum_max_workers + 1 + ! GetNumShmemAttachedBgworkers(); /* * Establish input sockets. *************** *** 5214,5219 **** RegisterBackgroundWorker(BackgroundWorker *worker) --- 5211,5227 ---- return; } + if (MaxConnections + autovacuum_max_workers + 1 + GetNumShmemAttachedBgworkers() >= + MAX_BACKENDS) + { + 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.", + MAX_BACKENDS - (MaxConnections + autovacuum_max_workers + 1)))); + return; + } + /* * Copy the registration data into the registered workers list. */ *************** *** 5836,5841 **** save_backend_variables(BackendParameters *param, Port *port, --- 5844,5851 ---- 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, *************** *** 6061,6066 **** restore_backend_variables(BackendParameters *param, Port *port) --- 6071,6078 ---- 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; *** a/src/backend/utils/init/globals.c --- b/src/backend/utils/init/globals.c *************** *** 103,115 **** 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): */ int NBuffers = 1000; - int MaxBackends = 100; int MaxConnections = 90; int VacuumCostPageHit = 1; /* GUC parameters for vacuum */ int VacuumCostPageMiss = 10; --- 103,116 ---- int maintenance_work_mem = 16384; /* ! * 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 MaxConnections = 90; + int MaxBackends = 0; int VacuumCostPageHit = 1; /* GUC parameters for vacuum */ int VacuumCostPageMiss = 10; *** a/src/backend/utils/misc/guc.c --- b/src/backend/utils/misc/guc.c *************** *** 103,119 **** #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) --- 103,108 ---- *************** *** 199,207 **** 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); --- 188,194 ---- *************** *** 1615,1621 **** static struct config_int ConfigureNamesInt[] = }, &MaxConnections, 100, 1, MAX_BACKENDS, ! check_maxconnections, assign_maxconnections, NULL }, { --- 1602,1608 ---- }, &MaxConnections, 100, 1, MAX_BACKENDS, ! check_maxconnections, NULL, NULL }, { *************** *** 2290,2296 **** static struct config_int ConfigureNamesInt[] = }, &autovacuum_max_workers, 3, 1, MAX_BACKENDS, ! check_autovacuum_max_workers, assign_autovacuum_max_workers, NULL }, { --- 2277,2283 ---- }, &autovacuum_max_workers, 3, 1, MAX_BACKENDS, ! check_autovacuum_max_workers, NULL, NULL }, { *************** *** 8636,8648 **** 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) { --- 8623,8628 ---- *************** *** 8652,8663 **** 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) { --- 8632,8637 ---- *** a/src/include/postmaster/postmaster.h --- b/src/include/postmaster/postmaster.h *************** *** 61,64 **** extern Size ShmemBackendArraySize(void); --- 61,73 ---- 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 */