diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/storage/lmgr/proc.c | 37 | ||||
| -rw-r--r-- | src/backend/utils/init/postinit.c | 8 | ||||
| -rw-r--r-- | src/include/miscadmin.h | 9 | ||||
| -rw-r--r-- | src/include/storage/proc.h | 14 |
4 files changed, 44 insertions, 24 deletions
diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c index 720ef99ee83..10d4fb4ea1a 100644 --- a/src/backend/storage/lmgr/proc.c +++ b/src/backend/storage/lmgr/proc.c @@ -197,11 +197,12 @@ InitProcGlobal(void) /* * Create and initialize all the PGPROC structures we'll need. There are - * five separate consumers: (1) normal backends, (2) autovacuum workers - * and the autovacuum launcher, (3) background workers, (4) auxiliary - * processes, and (5) prepared transactions. Each PGPROC structure is - * dedicated to exactly one of these purposes, and they do not move - * between groups. + * six separate consumers: (1) normal backends, (2) autovacuum workers and + * special workers, (3) background workers, (4) walsenders, (5) auxiliary + * processes, and (6) prepared transactions. (For largely-historical + * reasons, we combine autovacuum and special workers into one category + * with a single freelist.) Each PGPROC structure is dedicated to exactly + * one of these purposes, and they do not move between groups. */ procs = (PGPROC *) ShmemAlloc(TotalProcs * sizeof(PGPROC)); MemSet(procs, 0, TotalProcs * sizeof(PGPROC)); @@ -269,12 +270,13 @@ InitProcGlobal(void) } /* - * Newly created PGPROCs for normal backends, autovacuum and bgworkers - * must be queued up on the appropriate free list. Because there can - * only ever be a small, fixed number of auxiliary processes, no free - * list is used in that case; InitAuxiliaryProcess() instead uses a - * linear search. PGPROCs for prepared transactions are added to a - * free list by TwoPhaseShmemInit(). + * Newly created PGPROCs for normal backends, autovacuum workers, + * special workers, bgworkers, and walsenders must be queued up on the + * appropriate free list. Because there can only ever be a small, + * fixed number of auxiliary processes, no free list is used in that + * case; InitAuxiliaryProcess() instead uses a linear search. PGPROCs + * for prepared transactions are added to a free list by + * TwoPhaseShmemInit(). */ if (i < MaxConnections) { @@ -282,13 +284,13 @@ InitProcGlobal(void) dlist_push_tail(&ProcGlobal->freeProcs, &proc->links); proc->procgloballist = &ProcGlobal->freeProcs; } - else if (i < MaxConnections + autovacuum_max_workers + 1) + else if (i < MaxConnections + autovacuum_max_workers + NUM_SPECIAL_WORKER_PROCS) { - /* PGPROC for AV launcher/worker, add to autovacFreeProcs list */ + /* PGPROC for AV or special worker, add to autovacFreeProcs list */ dlist_push_tail(&ProcGlobal->autovacFreeProcs, &proc->links); proc->procgloballist = &ProcGlobal->autovacFreeProcs; } - else if (i < MaxConnections + autovacuum_max_workers + 1 + max_worker_processes) + else if (i < MaxConnections + autovacuum_max_workers + NUM_SPECIAL_WORKER_PROCS + max_worker_processes) { /* PGPROC for bgworker, add to bgworkerFreeProcs list */ dlist_push_tail(&ProcGlobal->bgworkerFreeProcs, &proc->links); @@ -358,8 +360,11 @@ InitProcess(void) if (IsUnderPostmaster) RegisterPostmasterChildActive(); - /* Decide which list should supply our PGPROC. */ - if (AmAutoVacuumLauncherProcess() || AmAutoVacuumWorkerProcess()) + /* + * Decide which list should supply our PGPROC. This logic must match the + * way the freelists were constructed in InitProcGlobal(). + */ + if (AmAutoVacuumWorkerProcess() || AmSpecialWorkerProcess()) procgloballist = &ProcGlobal->autovacFreeProcs; else if (AmBackgroundWorkerProcess()) procgloballist = &ProcGlobal->bgworkerFreeProcs; diff --git a/src/backend/utils/init/postinit.c b/src/backend/utils/init/postinit.c index 770ab6906e7..9731de5781d 100644 --- a/src/backend/utils/init/postinit.c +++ b/src/backend/utils/init/postinit.c @@ -544,9 +544,9 @@ InitializeMaxBackends(void) { Assert(MaxBackends == 0); - /* the extra unit accounts for the autovacuum launcher */ - MaxBackends = MaxConnections + autovacuum_max_workers + 1 + - max_worker_processes + max_wal_senders; + /* Note that this does not include "auxiliary" processes */ + MaxBackends = MaxConnections + autovacuum_max_workers + + max_worker_processes + max_wal_senders + NUM_SPECIAL_WORKER_PROCS; if (MaxBackends > MAX_BACKENDS) ereport(ERROR, @@ -555,7 +555,7 @@ InitializeMaxBackends(void) errdetail("\"max_connections\" (%d) plus \"autovacuum_max_workers\" (%d) plus \"max_worker_processes\" (%d) plus \"max_wal_senders\" (%d) must be less than %d.", MaxConnections, autovacuum_max_workers, max_worker_processes, max_wal_senders, - MAX_BACKENDS))); + MAX_BACKENDS - (NUM_SPECIAL_WORKER_PROCS - 1)))); } /* diff --git a/src/include/miscadmin.h b/src/include/miscadmin.h index 3f97fcef800..d07181f9321 100644 --- a/src/include/miscadmin.h +++ b/src/include/miscadmin.h @@ -350,8 +350,9 @@ typedef enum BackendType /* * Auxiliary processes. These have PGPROC entries, but they are not - * attached to any particular database. There can be only one of each of - * these running at a time. + * attached to any particular database, and cannot run transactions or + * even take heavyweight locks. There can be only one of each of these + * running at a time. * * If you modify these, make sure to update NUM_AUXILIARY_PROCS and the * glossary in the docs. @@ -388,6 +389,10 @@ extern PGDLLIMPORT BackendType MyBackendType; #define AmWalSummarizerProcess() (MyBackendType == B_WAL_SUMMARIZER) #define AmWalWriterProcess() (MyBackendType == B_WAL_WRITER) +#define AmSpecialWorkerProcess() \ + (AmAutoVacuumLauncherProcess() || \ + AmLogicalSlotSyncWorkerProcess()) + extern const char *GetBackendTypeDesc(BackendType backendType); extern void SetDatabasePath(const char *path); diff --git a/src/include/storage/proc.h b/src/include/storage/proc.h index 5a3dd5d2d40..14e34d4e933 100644 --- a/src/include/storage/proc.h +++ b/src/include/storage/proc.h @@ -408,7 +408,7 @@ typedef struct PROC_HDR uint32 allProcCount; /* Head of list of free PGPROC structures */ dlist_head freeProcs; - /* Head of list of autovacuum's free PGPROC structures */ + /* Head of list of autovacuum & special worker free PGPROC structures */ dlist_head autovacFreeProcs; /* Head of list of bgworker free PGPROC structures */ dlist_head bgworkerFreeProcs; @@ -443,8 +443,18 @@ extern PGDLLIMPORT PGPROC *PreparedXactProcs; #define GetNumberFromPGProc(proc) ((proc) - &ProcGlobal->allProcs[0]) /* + * We set aside some extra PGPROC structures for "special worker" processes, + * which are full-fledged backends (they can run transactions) + * but are unique animals that there's never more than one of. + * Currently there are two such processes: the autovacuum launcher + * and the slotsync worker. + */ +#define NUM_SPECIAL_WORKER_PROCS 2 + +/* * We set aside some extra PGPROC structures for auxiliary processes, - * ie things that aren't full-fledged backends but need shmem access. + * ie things that aren't full-fledged backends (they cannot run transactions + * or take heavyweight locks) but need shmem access. * * Background writer, checkpointer, WAL writer, WAL summarizer, and archiver * run during normal operation. Startup process and WAL receiver also consume |