Move the responsibility for calling StartupXLOG into InitPostgres, for

those process types that go through InitPostgres; in particular, bootstrap
and standalone-backend cases.  This ensures that we have set up a PGPROC
and done some other basic initialization steps (corresponding to the
if (IsUnderPostmaster) block in AuxiliaryProcessMain) before we attempt to
run WAL recovery in a standalone backend.  As was discovered last September,
this is necessary for some corner-case code paths during WAL recovery,
particularly end-of-WAL cleanup.

Moving the bootstrap case here too is not necessary for correctness, but it
seems like a good idea since it reduces the number of distinct code paths.

src/backend/bootstrap/bootstrap.c

@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/bootstrap/bootstrap.c,v 1.260 2010/02/26 02:00:35 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/bootstrap/bootstrap.c,v 1.261 2010/04/20 01:38:52 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -397,14 +397,13 @@ AuxiliaryProcessMain(int argc, char *argv[])
 	switch (auxType)
 	{
 		case CheckerProcess:
-			bootstrap_signals();
+			/* don't set signals, they're useless here */
 			CheckerModeMain();
 			proc_exit(1);		/* should never return */
 
 		case BootstrapProcess:
 			bootstrap_signals();
 			BootStrapXLOG();
-			StartupXLOG();
 			BootstrapModeMain();
 			proc_exit(1);		/* should never return */
 
@@ -438,23 +437,12 @@ AuxiliaryProcessMain(int argc, char *argv[])
 /*
  * In shared memory checker mode, all we really want to do is create shared
  * memory and semaphores (just to prove we can do it with the current GUC
- * settings).
+ * settings).  Since, in fact, that was already done by BaseInit(),
+ * we have nothing more to do here.
  */
 static void
 CheckerModeMain(void)
 {
-	/*
-	 * We must be getting invoked for bootstrap mode
-	 */
-	Assert(!IsUnderPostmaster);
-
-	SetProcessingMode(BootstrapProcessing);
-
-	/*
-	 * Do backend-like initialization for bootstrap mode
-	 */
-	InitProcess();
-	InitPostgres(NULL, InvalidOid, NULL, NULL);
 	proc_exit(0);
 }
 
@@ -478,6 +466,7 @@ BootstrapModeMain(void)
 	 * Do backend-like initialization for bootstrap mode
 	 */
 	InitProcess();
+
 	InitPostgres(NULL, InvalidOid, NULL, NULL);
 
 	/* Initialize stuff for bootstrap-file processing */
@@ -498,10 +487,6 @@ BootstrapModeMain(void)
 	 */
 	RelationMapFinishBootstrap();
 
-	/* Perform a checkpoint to ensure everything's down to disk */
-	SetProcessingMode(NormalProcessing);
-	CreateCheckPoint(CHECKPOINT_IS_SHUTDOWN | CHECKPOINT_IMMEDIATE);
-
 	/* Clean up and exit */
 	cleanup();
 	proc_exit(0);

src/backend/tcop/postgres.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.592 2010/03/21 00:17:58 petere Exp $
+ *	  $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.593 2010/04/20 01:38:52 tgl Exp $
  *
  * NOTES
  *	  this is the "main" module of the postgres backend and
@@ -3531,11 +3531,7 @@ PostgresMain(int argc, char *argv[], const char *username)
 
 	PG_SETMASK(&BlockSig);		/* block everything except SIGQUIT */
 
-	if (IsUnderPostmaster)
-	{
-		BaseInit();
-	}
-	else
+	if (!IsUnderPostmaster)
 	{
 		/*
 		 * Validate we have been given a reasonable-looking DataDir (if under
@@ -3551,17 +3547,11 @@ PostgresMain(int argc, char *argv[], const char *username)
 		 * Create lockfile for data directory.
 		 */
 		CreateDataDirLockFile(false);
-
-		BaseInit();
-
-		/*
-		 * Start up xlog for standalone backend, and register to have it
-		 * closed down at exit.
-		 */
-		StartupXLOG();
-		on_shmem_exit(ShutdownXLOG, 0);
 	}
 
+	/* Early initialization */
+	BaseInit();
+
 	/*
 	 * Create a per-backend PGPROC struct in shared memory, except in the
 	 * EXEC_BACKEND case where this was done in SubPostmasterMain. We must do

src/backend/utils/init/postinit.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/init/postinit.c,v 1.208 2010/03/25 20:40:17 sriggs Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/init/postinit.c,v 1.209 2010/04/20 01:38:52 tgl Exp $
  *
  *
  *-------------------------------------------------------------------------
@@ -427,11 +427,9 @@ pg_split_opts(char **argv, int *argcp, char *optstr)
  * Early initialization of a backend (either standalone or under postmaster).
  * This happens even before InitPostgres.
  *
- * If you're wondering why this is separate from InitPostgres at all:
- * the critical distinction is that this stuff has to happen before we can
- * run XLOG-related initialization, which is done before InitPostgres --- in
- * fact, for cases such as the background writer process, InitPostgres may
- * never be done at all.
+ * This is separate from InitPostgres because it is also called by auxiliary
+ * processes, such as the background writer process, which may not call
+ * InitPostgres at all.
  */
 void
 BaseInit(void)
@@ -512,11 +510,28 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
 	InitBufferPoolBackend();
 
 	/*
-	 * Initialize local process's access to XLOG, if appropriate.  In
-	 * bootstrap case we skip this since StartupXLOG() was run instead.
+	 * Initialize local process's access to XLOG.
+	 */
+	if (IsUnderPostmaster)
+	{
+		/*
+		 * The postmaster already started the XLOG machinery, but we need
+		 * to call InitXLOGAccess(), if the system isn't in hot-standby mode.
+		 * This is handled by calling RecoveryInProgress and ignoring the
+		 * result.
 		 */
-	if (!bootstrap)
 		(void) RecoveryInProgress();
+	}
+	else
+	{
+		/*
+		 * We are either a bootstrap process or a standalone backend.
+		 * Either way, start up the XLOG machinery, and register to have it
+		 * closed down at exit.
+		 */
+		StartupXLOG();
+		on_shmem_exit(ShutdownXLOG, 0);
+	}
 
 	/*
 	 * Initialize the relation cache and the system catalog caches.  Note that