maxbackend-macro.patch

*** a/src/backend/access/nbtree/nbtutils.c
--- b/src/backend/access/nbtree/nbtutils.c
***************
*** 21,26 ****
--- 21,27 ----
  #include "access/reloptions.h"
  #include "access/relscan.h"
  #include "miscadmin.h"
+ #include "storage/proc.h"
  #include "utils/array.h"
  #include "utils/lsyscache.h"
  #include "utils/memutils.h"
*** a/src/backend/access/transam/multixact.c
--- b/src/backend/access/transam/multixact.c
***************
*** 57,62 ****
--- 57,63 ----
  #include "miscadmin.h"
  #include "pg_trace.h"
  #include "storage/lmgr.h"
+ #include "storage/proc.h"
  #include "storage/procarray.h"
  #include "utils/builtins.h"
  #include "utils/memutils.h"
*** a/src/backend/commands/async.c
--- b/src/backend/commands/async.c
***************
*** 126,131 ****
--- 126,132 ----
  #include "miscadmin.h"
  #include "storage/ipc.h"
  #include "storage/lmgr.h"
+ #include "storage/proc.h"
  #include "storage/procsignal.h"
  #include "storage/sinval.h"
  #include "tcop/tcopprot.h"
*** a/src/backend/libpq/pqcomm.c
--- b/src/backend/libpq/pqcomm.c
***************
*** 93,98 ****
--- 93,99 ----
  #include "libpq/libpq.h"
  #include "miscadmin.h"
  #include "storage/ipc.h"
+ #include "storage/proc.h"
  #include "utils/guc.h"
  #include "utils/memutils.h"
  
*** a/src/backend/postmaster/autovacuum.c
--- b/src/backend/postmaster/autovacuum.c
***************
*** 108,114 ****
   * GUC parameters
   */
  bool		autovacuum_start_daemon = false;
! int			autovacuum_max_workers;
  int			autovacuum_naptime;
  int			autovacuum_vac_thresh;
  double		autovacuum_vac_scale;
--- 108,114 ----
   * GUC parameters
   */
  bool		autovacuum_start_daemon = false;
! /* autovacuum_max_workers is elsewhere */
  int			autovacuum_naptime;
  int			autovacuum_vac_thresh;
  double		autovacuum_vac_scale;
*** a/src/backend/postmaster/pgstat.c
--- b/src/backend/postmaster/pgstat.c
***************
*** 52,57 ****
--- 52,58 ----
  #include "storage/ipc.h"
  #include "storage/latch.h"
  #include "storage/pg_shmem.h"
+ #include "storage/proc.h"
  #include "storage/procsignal.h"
  #include "utils/ascii.h"
  #include "utils/guc.h"
*** a/src/backend/postmaster/postmaster.c
--- b/src/backend/postmaster/postmaster.c
***************
*** 897,913 **** 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.
  	 */
  	for (i = 0; i < MAXLISTEN; i++)
--- 897,902 ----
***************
*** 5176,5181 **** RegisterBackgroundWorker(BackgroundWorker *worker)
--- 5165,5180 ----
  		return;
  	}
  
+ 	if (MaxBackends >= MAX_BACKENDS)
+ 	{
+ 		ereport(LOG,
+ 				(errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
+ 				 errmsg("too many background workers"),
+ 				 errhint("max_connections plus autovacuum_max_workers plus the total number of background workers cannot exceed %d",
+ 						 MAX_BACKENDS - 1)));
+ 		return;
+ 	}
+ 
  	/* sanity check for flags */
  	if (worker->bgw_flags & BGWORKER_BACKEND_DATABASE_CONNECTION)
  	{
*** a/src/backend/storage/ipc/procsignal.c
--- b/src/backend/storage/ipc/procsignal.c
***************
*** 21,26 ****
--- 21,27 ----
  #include "miscadmin.h"
  #include "storage/latch.h"
  #include "storage/ipc.h"
+ #include "storage/proc.h"
  #include "storage/shmem.h"
  #include "storage/sinval.h"
  #include "tcop/tcopprot.h"
*** 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;
--- 103,113 ----
  int			maintenance_work_mem = 16384;
  
  /*
!  * Primary determinants of sizes of shared-memory structures.
   */
  int			NBuffers = 1000;
  int			MaxConnections = 90;
+ int			autovacuum_max_workers = 3;
  
  int			VacuumCostPageHit = 1;		/* GUC parameters for vacuum */
  int			VacuumCostPageMiss = 10;
*** a/src/backend/utils/misc/guc.c
--- b/src/backend/utils/misc/guc.c
***************
*** 103,118 ****
  #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);
--- 189,195 ----
***************
*** 1615,1621 **** static struct config_int ConfigureNamesInt[] =
  		},
  		&MaxConnections,
  		100, 1, MAX_BACKENDS,
! 		check_maxconnections, assign_maxconnections, NULL
  	},
  
  	{
--- 1603,1609 ----
  		},
  		&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
  	},
  
  	{
--- 2278,2284 ----
  		},
  		&autovacuum_max_workers,
  		3, 1, MAX_BACKENDS,
! 		check_autovacuum_max_workers, NULL, NULL
  	},
  
  	{
***************
*** 8630,8648 **** show_tcp_keepalives_count(void)
  static bool
  check_maxconnections(int *newval, void **extra, GucSource source)
  {
! 	if (*newval + GetNumShmemAttachedBgworkers() + autovacuum_max_workers + 1 >
  		MAX_BACKENDS)
  		return false;
  	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)
  {
--- 8618,8629 ----
  static bool
  check_maxconnections(int *newval, void **extra, GucSource source)
  {
! 	if (*newval + autovacuum_max_workers + 1 + GetNumShmemAttachedBgworkers() >
  		MAX_BACKENDS)
  		return false;
  	return true;
  }
  
  static bool
  check_autovacuum_max_workers(int *newval, void **extra, GucSource source)
  {
***************
*** 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)
  {
--- 8633,8638 ----
*** a/src/include/miscadmin.h
--- b/src/include/miscadmin.h
***************
*** 139,146 **** extern bool ExitOnAnyError;
  extern PGDLLIMPORT char *DataDir;
  
  extern PGDLLIMPORT int NBuffers;
- extern int	MaxBackends;
- extern int	MaxConnections;
  
  extern PGDLLIMPORT int MyProcPid;
  extern PGDLLIMPORT pg_time_t MyStartTime;
--- 139,144 ----
*** a/src/include/postmaster/autovacuum.h
--- b/src/include/postmaster/autovacuum.h
***************
*** 17,23 ****
  
  /* GUC variables */
  extern bool autovacuum_start_daemon;
! extern int	autovacuum_max_workers;
  extern int	autovacuum_naptime;
  extern int	autovacuum_vac_thresh;
  extern double autovacuum_vac_scale;
--- 17,23 ----
  
  /* GUC variables */
  extern bool autovacuum_start_daemon;
! /* autovacuum_max_workers is elsewhere */
  extern int	autovacuum_naptime;
  extern int	autovacuum_vac_thresh;
  extern double autovacuum_vac_scale;
*** a/src/include/storage/proc.h
--- b/src/include/storage/proc.h
***************
*** 15,24 ****
--- 15,43 ----
  #define _PROC_H_
  
  #include "access/xlogdefs.h"
+ #include "postmaster/postmaster.h"
  #include "storage/latch.h"
  #include "storage/lock.h"
  #include "storage/pg_sema.h"
  
+ 
+ /*
+  * GUC variables determining the maximum number of backend processes.
+  */
+ extern int	MaxConnections;
+ extern int	autovacuum_max_workers;
+ #define MaxBackends (MaxConnections + autovacuum_max_workers + 1 + \
+ 					 GetNumShmemAttachedBgworkers())
+ /*
+  * 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 and check_autovacuum_max_workers, and also in the
+  * background worker registration code.
+  */
+ #define MAX_BACKENDS	0x7fffff
+ 
  /*
   * Each backend advertises up to PGPROC_MAX_CACHED_SUBXIDS TransactionIds
   * for non-aborted subtransactions of its current top transaction.	These