From 0cb6f8d665980d30a5d2a29013000744f16bf813 Mon Sep 17 00:00:00 2001 From: Heikki Linnakangas Date: Sun, 18 Jun 2023 11:00:21 +0300 Subject: [PATCH 3/9] Refactor CreateSharedMemoryAndSemaphores. Moves InitProcess calls a little later in EXEC_BACKEND case. For clarity, have separate functions for *creating* the shared memory and semaphores, at postmaster or single-user backend startup, and for *attaching* to existing shared memory structures in EXEC_BACKEND case. I find it pretty confusing in all the *ShmemInit() functions too, that they are called in two different contexts: in postmaster when creating the shmem structs, and in the child process in EXEC_BACKEND when attaching to the already existing structs. But this commit doesn't change that. --- src/backend/postmaster/autovacuum.c | 22 ++++++------- src/backend/postmaster/auxprocess.c | 8 ++--- src/backend/postmaster/bgworker.c | 11 +++---- src/backend/postmaster/postmaster.c | 48 ++++++----------------------- src/backend/storage/ipc/ipci.c | 11 +++++++ src/backend/storage/lmgr/proc.c | 2 +- src/include/storage/ipc.h | 1 + 7 files changed, 41 insertions(+), 62 deletions(-) diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c index f929b62e8ad..7157c5466aa 100644 --- a/src/backend/postmaster/autovacuum.c +++ b/src/backend/postmaster/autovacuum.c @@ -476,14 +476,13 @@ AutoVacLauncherMain(int argc, char *argv[]) pqsignal(SIGCHLD, SIG_DFL); /* - * Create a per-backend PGPROC struct in shared memory, except in the - * EXEC_BACKEND case where this was done in SubPostmasterMain. We must do - * this before we can use LWLocks (and in the EXEC_BACKEND case we already - * had to do some stuff with LWLocks). + * Create a per-backend PGPROC struct in shared memory. We must do + * this before we can use LWLocks. */ -#ifndef EXEC_BACKEND InitProcess(); -#endif + + /* Attach process to shared data structures */ + AttachSharedMemoryAndSemaphores(); /* Early initialization */ BaseInit(); @@ -1548,14 +1547,13 @@ AutoVacWorkerMain(int argc, char *argv[]) pqsignal(SIGCHLD, SIG_DFL); /* - * Create a per-backend PGPROC struct in shared memory, except in the - * EXEC_BACKEND case where this was done in SubPostmasterMain. We must do - * this before we can use LWLocks (and in the EXEC_BACKEND case we already - * had to do some stuff with LWLocks). + * Create a per-backend PGPROC struct in shared memory. We must do + * this before we can use LWLocks. */ -#ifndef EXEC_BACKEND InitProcess(); -#endif + + /* Attach process to shared data structures */ + AttachSharedMemoryAndSemaphores(); /* Early initialization */ BaseInit(); diff --git a/src/backend/postmaster/auxprocess.c b/src/backend/postmaster/auxprocess.c index cae6feb3562..536d9a2b3e4 100644 --- a/src/backend/postmaster/auxprocess.c +++ b/src/backend/postmaster/auxprocess.c @@ -97,12 +97,12 @@ AuxiliaryProcessMain(AuxProcType auxtype) */ /* - * Create a PGPROC so we can use LWLocks. In the EXEC_BACKEND case, this - * was already done by SubPostmasterMain(). + * Create a PGPROC so we can use LWLocks. */ -#ifndef EXEC_BACKEND InitAuxiliaryProcess(); -#endif + + /* Attach process to shared data structures */ + AttachSharedMemoryAndSemaphores(); BaseInit(); diff --git a/src/backend/postmaster/bgworker.c b/src/backend/postmaster/bgworker.c index b7140306e43..13519ea0c45 100644 --- a/src/backend/postmaster/bgworker.c +++ b/src/backend/postmaster/bgworker.c @@ -810,14 +810,13 @@ StartBackgroundWorker(void) PG_exception_stack = &local_sigjmp_buf; /* - * Create a per-backend PGPROC struct in shared memory, except in the - * EXEC_BACKEND case where this was done in SubPostmasterMain. We must do - * this before we can use LWLocks (and in the EXEC_BACKEND case we already - * had to do some stuff with LWLocks). + * Create a per-backend PGPROC struct in shared memory. We must do + * this before we can use LWLocks. */ -#ifndef EXEC_BACKEND InitProcess(); -#endif + + /* Attach process to shared data structures */ + AttachSharedMemoryAndSemaphores(); /* * Early initialization. diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c index a7a9e061c5b..bf9f0d27278 100644 --- a/src/backend/postmaster/postmaster.c +++ b/src/backend/postmaster/postmaster.c @@ -4176,15 +4176,6 @@ BackendStartup(Port *port) /* Perform additional initialization and collect startup packet */ BackendInitialize(port); - /* - * Create a per-backend PGPROC struct in shared memory. We must do - * this before we can use LWLocks. In the !EXEC_BACKEND case (here) - * this could be delayed a bit further, but EXEC_BACKEND needs to do - * stuff with LWLocks before PostgresMain(), so we do it here as well - * for symmetry. - */ - InitProcess(); - /* And run the backend */ BackendRun(port); } @@ -4452,6 +4443,15 @@ BackendInitialize(Port *port) static void BackendRun(Port *port) { + /* + * Create a per-backend PGPROC struct in shared memory. We must do + * this before we can use LWLocks (in AttachSharedMemoryAndSemaphores). + */ + InitProcess(); + + /* Attach process to shared data structures */ + AttachSharedMemoryAndSemaphores(); + /* * Make sure we aren't in PostmasterContext anymore. (We can't delete it * just yet, though, because InitPostgres will need the HBA data.) @@ -4947,12 +4947,6 @@ SubPostmasterMain(int argc, char *argv[]) /* Restore basic shared memory pointers */ InitShmemAccess(UsedShmemSegAddr); - /* Need a PGPROC to run CreateSharedMemoryAndSemaphores */ - InitProcess(); - - /* Attach process to shared data structures */ - CreateSharedMemoryAndSemaphores(); - /* And run the backend */ BackendRun(&port); /* does not return */ } @@ -4965,12 +4959,6 @@ SubPostmasterMain(int argc, char *argv[]) /* Restore basic shared memory pointers */ InitShmemAccess(UsedShmemSegAddr); - /* Need a PGPROC to run CreateSharedMemoryAndSemaphores */ - InitAuxiliaryProcess(); - - /* Attach process to shared data structures */ - CreateSharedMemoryAndSemaphores(); - auxtype = atoi(argv[3]); AuxiliaryProcessMain(auxtype); /* does not return */ } @@ -4979,12 +4967,6 @@ SubPostmasterMain(int argc, char *argv[]) /* Restore basic shared memory pointers */ InitShmemAccess(UsedShmemSegAddr); - /* Need a PGPROC to run CreateSharedMemoryAndSemaphores */ - InitProcess(); - - /* Attach process to shared data structures */ - CreateSharedMemoryAndSemaphores(); - AutoVacLauncherMain(argc - 2, argv + 2); /* does not return */ } if (strcmp(argv[1], "--forkavworker") == 0) @@ -4992,12 +4974,6 @@ SubPostmasterMain(int argc, char *argv[]) /* Restore basic shared memory pointers */ InitShmemAccess(UsedShmemSegAddr); - /* Need a PGPROC to run CreateSharedMemoryAndSemaphores */ - InitProcess(); - - /* Attach process to shared data structures */ - CreateSharedMemoryAndSemaphores(); - AutoVacWorkerMain(argc - 2, argv + 2); /* does not return */ } if (strncmp(argv[1], "--forkbgworker", 14) == 0) @@ -5008,12 +4984,6 @@ SubPostmasterMain(int argc, char *argv[]) /* Restore basic shared memory pointers */ InitShmemAccess(UsedShmemSegAddr); - /* Need a PGPROC to run CreateSharedMemoryAndSemaphores */ - InitProcess(); - - /* Attach process to shared data structures */ - CreateSharedMemoryAndSemaphores(); - StartBackgroundWorker(); } if (strcmp(argv[1], "--forklog") == 0) diff --git a/src/backend/storage/ipc/ipci.c b/src/backend/storage/ipc/ipci.c index 8f1ded7338f..be6a774e351 100644 --- a/src/backend/storage/ipc/ipci.c +++ b/src/backend/storage/ipc/ipci.c @@ -170,6 +170,17 @@ CalculateShmemSize(int *num_semaphores) * check IsUnderPostmaster, rather than EXEC_BACKEND, to detect this case. * This is a bit code-wasteful and could be cleaned up.) */ +void +AttachSharedMemoryAndSemaphores(void) +{ + /* InitProcess must've been called already */ + + /* Init !EXEC_BACKEND mode, we inherited everything through the fork */ +#ifdef EXEC_BACKEND + CreateSharedMemoryAndSemaphores(); +#endif +} + void CreateSharedMemoryAndSemaphores(void) { diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c index dac921219fa..91f415aa783 100644 --- a/src/backend/storage/lmgr/proc.c +++ b/src/backend/storage/lmgr/proc.c @@ -468,7 +468,7 @@ InitProcess(void) * * This is separate from InitProcess because we can't acquire LWLocks until * we've created a PGPROC, but in the EXEC_BACKEND case ProcArrayAdd won't - * work until after we've done CreateSharedMemoryAndSemaphores. + * work until after we've done AttachSharedMemoryAndSemaphores. */ void InitProcessPhase2(void) diff --git a/src/include/storage/ipc.h b/src/include/storage/ipc.h index 888c08b3067..e75656f5242 100644 --- a/src/include/storage/ipc.h +++ b/src/include/storage/ipc.h @@ -79,6 +79,7 @@ extern PGDLLIMPORT shmem_startup_hook_type shmem_startup_hook; extern Size CalculateShmemSize(int *num_semaphores); extern void CreateSharedMemoryAndSemaphores(void); +extern void AttachSharedMemoryAndSemaphores(void); extern void InitializeShmemGUCs(void); #endif /* IPC_H */ -- 2.30.2