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-rw-r--r--src/backend/bootstrap/bootstrap.c2
-rw-r--r--src/backend/postmaster/postmaster.c5
-rw-r--r--src/backend/storage/ipc/ipci.c6
-rw-r--r--src/backend/storage/lmgr/lock.c125
-rw-r--r--src/backend/storage/lmgr/proc.c46
-rw-r--r--src/backend/tcop/postgres.c3
-rw-r--r--src/backend/utils/init/postinit.c34
-rw-r--r--src/include/miscadmin.h1
-rw-r--r--src/include/storage/proc.h17
9 files changed, 212 insertions, 27 deletions
diff --git a/src/backend/bootstrap/bootstrap.c b/src/backend/bootstrap/bootstrap.c
index 7637581a184..ed59dfce893 100644
--- a/src/backend/bootstrap/bootstrap.c
+++ b/src/backend/bootstrap/bootstrap.c
@@ -309,6 +309,8 @@ BootstrapModeMain(int argc, char *argv[], bool check_only)
InitializeMaxBackends();
+ InitializeFastPathLocks();
+
CreateSharedMemoryAndSemaphores();
/*
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 96bc1d1cfed..85fd24e8287 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -904,6 +904,11 @@ PostmasterMain(int argc, char *argv[])
InitializeMaxBackends();
/*
+ * Calculate the size of the PGPROC fast-path lock arrays.
+ */
+ InitializeFastPathLocks();
+
+ /*
* Give preloaded libraries a chance to request additional shared memory.
*/
process_shmem_requests();
diff --git a/src/backend/storage/ipc/ipci.c b/src/backend/storage/ipc/ipci.c
index 6caeca3a8e6..10fc18f2529 100644
--- a/src/backend/storage/ipc/ipci.c
+++ b/src/backend/storage/ipc/ipci.c
@@ -178,6 +178,12 @@ AttachSharedMemoryStructs(void)
Assert(MyProc != NULL);
Assert(IsUnderPostmaster);
+ /*
+ * In EXEC_BACKEND mode, backends don't inherit the number of fast-path
+ * groups we calculated before setting the shmem up, so recalculate it.
+ */
+ InitializeFastPathLocks();
+
CreateOrAttachShmemStructs();
/*
diff --git a/src/backend/storage/lmgr/lock.c b/src/backend/storage/lmgr/lock.c
index 83b99a98f08..613b0d49944 100644
--- a/src/backend/storage/lmgr/lock.c
+++ b/src/backend/storage/lmgr/lock.c
@@ -166,8 +166,13 @@ typedef struct TwoPhaseLockRecord
* might be higher than the real number if another backend has transferred
* our locks to the primary lock table, but it can never be lower than the
* real value, since only we can acquire locks on our own behalf.
+ *
+ * XXX Allocate a static array of the maximum size. We could use a pointer
+ * and then allocate just the right size to save a couple kB, but then we
+ * would have to initialize that, while for the static array that happens
+ * automatically. Doesn't seem worth the extra complexity.
*/
-static int FastPathLocalUseCount = 0;
+static int FastPathLocalUseCounts[FP_LOCK_GROUPS_PER_BACKEND_MAX];
/*
* Flag to indicate if the relation extension lock is held by this backend.
@@ -184,23 +189,68 @@ static int FastPathLocalUseCount = 0;
*/
static bool IsRelationExtensionLockHeld PG_USED_FOR_ASSERTS_ONLY = false;
+/*
+ * Number of fast-path locks per backend - size of the arrays in PGPROC.
+ * This is set only once during start, before initializing shared memory,
+ * and remains constant after that.
+ *
+ * We set the limit based on max_locks_per_transaction GUC, because that's
+ * the best information about expected number of locks per backend we have.
+ * See InitializeFastPathLocks() for details.
+ */
+int FastPathLockGroupsPerBackend = 0;
+
+/*
+ * Macros to calculate the fast-path group and index for a relation.
+ *
+ * The formula is a simple hash function, designed to spread the OIDs a bit,
+ * so that even contiguous values end up in different groups. In most cases
+ * there will be gaps anyway, but the multiplication should help a bit.
+ *
+ * The selected constant (49157) is a prime not too close to 2^k, and it's
+ * small enough to not cause overflows (in 64-bit).
+ */
+#define FAST_PATH_REL_GROUP(rel) \
+ (((uint64) (rel) * 49157) % FastPathLockGroupsPerBackend)
+
+/*
+ * Given the group/slot indexes, calculate the slot index in the whole array
+ * of fast-path lock slots.
+ */
+#define FAST_PATH_SLOT(group, index) \
+ (AssertMacro(((group) >= 0) && ((group) < FastPathLockGroupsPerBackend)), \
+ AssertMacro(((index) >= 0) && ((index) < FP_LOCK_SLOTS_PER_GROUP)), \
+ ((group) * FP_LOCK_SLOTS_PER_GROUP + (index)))
+
+/*
+ * Given a slot index (into the whole per-backend array), calculated using
+ * the FAST_PATH_SLOT macro, split it into group and index (in the group).
+ */
+#define FAST_PATH_GROUP(index) \
+ (AssertMacro(((index) >= 0) && ((index) < FP_LOCK_SLOTS_PER_BACKEND)), \
+ ((index) / FP_LOCK_SLOTS_PER_GROUP))
+#define FAST_PATH_INDEX(index) \
+ (AssertMacro(((index) >= 0) && ((index) < FP_LOCK_SLOTS_PER_BACKEND)), \
+ ((index) % FP_LOCK_SLOTS_PER_GROUP))
+
/* Macros for manipulating proc->fpLockBits */
#define FAST_PATH_BITS_PER_SLOT 3
#define FAST_PATH_LOCKNUMBER_OFFSET 1
#define FAST_PATH_MASK ((1 << FAST_PATH_BITS_PER_SLOT) - 1)
+#define FAST_PATH_BITS(proc, n) (proc)->fpLockBits[FAST_PATH_GROUP(n)]
#define FAST_PATH_GET_BITS(proc, n) \
- (((proc)->fpLockBits >> (FAST_PATH_BITS_PER_SLOT * n)) & FAST_PATH_MASK)
+ ((FAST_PATH_BITS(proc, n) >> (FAST_PATH_BITS_PER_SLOT * FAST_PATH_INDEX(n))) & FAST_PATH_MASK)
#define FAST_PATH_BIT_POSITION(n, l) \
(AssertMacro((l) >= FAST_PATH_LOCKNUMBER_OFFSET), \
AssertMacro((l) < FAST_PATH_BITS_PER_SLOT+FAST_PATH_LOCKNUMBER_OFFSET), \
AssertMacro((n) < FP_LOCK_SLOTS_PER_BACKEND), \
- ((l) - FAST_PATH_LOCKNUMBER_OFFSET + FAST_PATH_BITS_PER_SLOT * (n)))
+ ((l) - FAST_PATH_LOCKNUMBER_OFFSET + FAST_PATH_BITS_PER_SLOT * (FAST_PATH_INDEX(n))))
#define FAST_PATH_SET_LOCKMODE(proc, n, l) \
- (proc)->fpLockBits |= UINT64CONST(1) << FAST_PATH_BIT_POSITION(n, l)
+ FAST_PATH_BITS(proc, n) |= UINT64CONST(1) << FAST_PATH_BIT_POSITION(n, l)
#define FAST_PATH_CLEAR_LOCKMODE(proc, n, l) \
- (proc)->fpLockBits &= ~(UINT64CONST(1) << FAST_PATH_BIT_POSITION(n, l))
+ FAST_PATH_BITS(proc, n) &= ~(UINT64CONST(1) << FAST_PATH_BIT_POSITION(n, l))
#define FAST_PATH_CHECK_LOCKMODE(proc, n, l) \
- ((proc)->fpLockBits & (UINT64CONST(1) << FAST_PATH_BIT_POSITION(n, l)))
+ (FAST_PATH_BITS(proc, n) & (UINT64CONST(1) << FAST_PATH_BIT_POSITION(n, l)))
/*
* The fast-path lock mechanism is concerned only with relation locks on
@@ -926,7 +976,7 @@ LockAcquireExtended(const LOCKTAG *locktag,
* for now we don't worry about that case either.
*/
if (EligibleForRelationFastPath(locktag, lockmode) &&
- FastPathLocalUseCount < FP_LOCK_SLOTS_PER_BACKEND)
+ FastPathLocalUseCounts[FAST_PATH_REL_GROUP(locktag->locktag_field2)] < FP_LOCK_SLOTS_PER_GROUP)
{
uint32 fasthashcode = FastPathStrongLockHashPartition(hashcode);
bool acquired;
@@ -2065,7 +2115,7 @@ LockRelease(const LOCKTAG *locktag, LOCKMODE lockmode, bool sessionLock)
/* Attempt fast release of any lock eligible for the fast path. */
if (EligibleForRelationFastPath(locktag, lockmode) &&
- FastPathLocalUseCount > 0)
+ FastPathLocalUseCounts[FAST_PATH_REL_GROUP(locktag->locktag_field2)] > 0)
{
bool released;
@@ -2633,12 +2683,18 @@ LockReassignOwner(LOCALLOCK *locallock, ResourceOwner parent)
static bool
FastPathGrantRelationLock(Oid relid, LOCKMODE lockmode)
{
- uint32 f;
+ uint32 i;
uint32 unused_slot = FP_LOCK_SLOTS_PER_BACKEND;
+ /* fast-path group the lock belongs to */
+ uint32 group = FAST_PATH_REL_GROUP(relid);
+
/* Scan for existing entry for this relid, remembering empty slot. */
- for (f = 0; f < FP_LOCK_SLOTS_PER_BACKEND; f++)
+ for (i = 0; i < FP_LOCK_SLOTS_PER_GROUP; i++)
{
+ /* index into the whole per-backend array */
+ uint32 f = FAST_PATH_SLOT(group, i);
+
if (FAST_PATH_GET_BITS(MyProc, f) == 0)
unused_slot = f;
else if (MyProc->fpRelId[f] == relid)
@@ -2654,7 +2710,7 @@ FastPathGrantRelationLock(Oid relid, LOCKMODE lockmode)
{
MyProc->fpRelId[unused_slot] = relid;
FAST_PATH_SET_LOCKMODE(MyProc, unused_slot, lockmode);
- ++FastPathLocalUseCount;
+ ++FastPathLocalUseCounts[group];
return true;
}
@@ -2670,12 +2726,18 @@ FastPathGrantRelationLock(Oid relid, LOCKMODE lockmode)
static bool
FastPathUnGrantRelationLock(Oid relid, LOCKMODE lockmode)
{
- uint32 f;
+ uint32 i;
bool result = false;
- FastPathLocalUseCount = 0;
- for (f = 0; f < FP_LOCK_SLOTS_PER_BACKEND; f++)
+ /* fast-path group the lock belongs to */
+ uint32 group = FAST_PATH_REL_GROUP(relid);
+
+ FastPathLocalUseCounts[group] = 0;
+ for (i = 0; i < FP_LOCK_SLOTS_PER_GROUP; i++)
{
+ /* index into the whole per-backend array */
+ uint32 f = FAST_PATH_SLOT(group, i);
+
if (MyProc->fpRelId[f] == relid
&& FAST_PATH_CHECK_LOCKMODE(MyProc, f, lockmode))
{
@@ -2685,7 +2747,7 @@ FastPathUnGrantRelationLock(Oid relid, LOCKMODE lockmode)
/* we continue iterating so as to update FastPathLocalUseCount */
}
if (FAST_PATH_GET_BITS(MyProc, f) != 0)
- ++FastPathLocalUseCount;
+ ++FastPathLocalUseCounts[group];
}
return result;
}
@@ -2714,7 +2776,8 @@ FastPathTransferRelationLocks(LockMethod lockMethodTable, const LOCKTAG *locktag
for (i = 0; i < ProcGlobal->allProcCount; i++)
{
PGPROC *proc = &ProcGlobal->allProcs[i];
- uint32 f;
+ uint32 j,
+ group;
LWLockAcquire(&proc->fpInfoLock, LW_EXCLUSIVE);
@@ -2739,10 +2802,16 @@ FastPathTransferRelationLocks(LockMethod lockMethodTable, const LOCKTAG *locktag
continue;
}
- for (f = 0; f < FP_LOCK_SLOTS_PER_BACKEND; f++)
+ /* fast-path group the lock belongs to */
+ group = FAST_PATH_REL_GROUP(relid);
+
+ for (j = 0; j < FP_LOCK_SLOTS_PER_GROUP; j++)
{
uint32 lockmode;
+ /* index into the whole per-backend array */
+ uint32 f = FAST_PATH_SLOT(group, j);
+
/* Look for an allocated slot matching the given relid. */
if (relid != proc->fpRelId[f] || FAST_PATH_GET_BITS(proc, f) == 0)
continue;
@@ -2793,14 +2862,21 @@ FastPathGetRelationLockEntry(LOCALLOCK *locallock)
PROCLOCK *proclock = NULL;
LWLock *partitionLock = LockHashPartitionLock(locallock->hashcode);
Oid relid = locktag->locktag_field2;
- uint32 f;
+ uint32 i,
+ group;
+
+ /* fast-path group the lock belongs to */
+ group = FAST_PATH_REL_GROUP(relid);
LWLockAcquire(&MyProc->fpInfoLock, LW_EXCLUSIVE);
- for (f = 0; f < FP_LOCK_SLOTS_PER_BACKEND; f++)
+ for (i = 0; i < FP_LOCK_SLOTS_PER_GROUP; i++)
{
uint32 lockmode;
+ /* index into the whole per-backend array */
+ uint32 f = FAST_PATH_SLOT(group, i);
+
/* Look for an allocated slot matching the given relid. */
if (relid != MyProc->fpRelId[f] || FAST_PATH_GET_BITS(MyProc, f) == 0)
continue;
@@ -2957,7 +3033,8 @@ GetLockConflicts(const LOCKTAG *locktag, LOCKMODE lockmode, int *countp)
for (i = 0; i < ProcGlobal->allProcCount; i++)
{
PGPROC *proc = &ProcGlobal->allProcs[i];
- uint32 f;
+ uint32 j,
+ group;
/* A backend never blocks itself */
if (proc == MyProc)
@@ -2979,10 +3056,16 @@ GetLockConflicts(const LOCKTAG *locktag, LOCKMODE lockmode, int *countp)
continue;
}
- for (f = 0; f < FP_LOCK_SLOTS_PER_BACKEND; f++)
+ /* fast-path group the lock belongs to */
+ group = FAST_PATH_REL_GROUP(relid);
+
+ for (j = 0; j < FP_LOCK_SLOTS_PER_GROUP; j++)
{
uint32 lockmask;
+ /* index into the whole per-backend array */
+ uint32 f = FAST_PATH_SLOT(group, j);
+
/* Look for an allocated slot matching the given relid. */
if (relid != proc->fpRelId[f])
continue;
diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c
index ac66da8638f..9b72829725a 100644
--- a/src/backend/storage/lmgr/proc.c
+++ b/src/backend/storage/lmgr/proc.c
@@ -103,6 +103,8 @@ ProcGlobalShmemSize(void)
Size size = 0;
Size TotalProcs =
add_size(MaxBackends, add_size(NUM_AUXILIARY_PROCS, max_prepared_xacts));
+ Size fpLockBitsSize,
+ fpRelIdSize;
/* ProcGlobal */
size = add_size(size, sizeof(PROC_HDR));
@@ -113,6 +115,15 @@ ProcGlobalShmemSize(void)
size = add_size(size, mul_size(TotalProcs, sizeof(*ProcGlobal->subxidStates)));
size = add_size(size, mul_size(TotalProcs, sizeof(*ProcGlobal->statusFlags)));
+ /*
+ * Memory needed for PGPROC fast-path lock arrays. Make sure the sizes are
+ * nicely aligned in each backend.
+ */
+ fpLockBitsSize = MAXALIGN(FastPathLockGroupsPerBackend * sizeof(uint64));
+ fpRelIdSize = MAXALIGN(FastPathLockGroupsPerBackend * sizeof(Oid) * FP_LOCK_SLOTS_PER_GROUP);
+
+ size = add_size(size, mul_size(TotalProcs, (fpLockBitsSize + fpRelIdSize)));
+
return size;
}
@@ -163,6 +174,12 @@ InitProcGlobal(void)
bool found;
uint32 TotalProcs = MaxBackends + NUM_AUXILIARY_PROCS + max_prepared_xacts;
+ /* Used for setup of per-backend fast-path slots. */
+ char *fpPtr,
+ *fpEndPtr PG_USED_FOR_ASSERTS_ONLY;
+ Size fpLockBitsSize,
+ fpRelIdSize;
+
/* Create the ProcGlobal shared structure */
ProcGlobal = (PROC_HDR *)
ShmemInitStruct("Proc Header", sizeof(PROC_HDR), &found);
@@ -211,6 +228,20 @@ InitProcGlobal(void)
ProcGlobal->statusFlags = (uint8 *) ShmemAlloc(TotalProcs * sizeof(*ProcGlobal->statusFlags));
MemSet(ProcGlobal->statusFlags, 0, TotalProcs * sizeof(*ProcGlobal->statusFlags));
+ /*
+ * Allocate arrays for fast-path locks. Those are variable-length, so
+ * can't be included in PGPROC directly. We allocate a separate piece of
+ * shared memory and then divide that between backends.
+ */
+ fpLockBitsSize = MAXALIGN(FastPathLockGroupsPerBackend * sizeof(uint64));
+ fpRelIdSize = MAXALIGN(FastPathLockGroupsPerBackend * sizeof(Oid) * FP_LOCK_SLOTS_PER_GROUP);
+
+ fpPtr = ShmemAlloc(TotalProcs * (fpLockBitsSize + fpRelIdSize));
+ MemSet(fpPtr, 0, TotalProcs * (fpLockBitsSize + fpRelIdSize));
+
+ /* For asserts checking we did not overflow. */
+ fpEndPtr = fpPtr + (TotalProcs * (fpLockBitsSize + fpRelIdSize));
+
for (i = 0; i < TotalProcs; i++)
{
PGPROC *proc = &procs[i];
@@ -218,6 +249,18 @@ InitProcGlobal(void)
/* Common initialization for all PGPROCs, regardless of type. */
/*
+ * Set the fast-path lock arrays, and move the pointer. We interleave
+ * the two arrays, to (hopefully) get some locality for each backend.
+ */
+ proc->fpLockBits = (uint64 *) fpPtr;
+ fpPtr += fpLockBitsSize;
+
+ proc->fpRelId = (Oid *) fpPtr;
+ fpPtr += fpRelIdSize;
+
+ Assert(fpPtr <= fpEndPtr);
+
+ /*
* Set up per-PGPROC semaphore, latch, and fpInfoLock. Prepared xact
* dummy PGPROCs don't need these though - they're never associated
* with a real process
@@ -278,6 +321,9 @@ InitProcGlobal(void)
pg_atomic_init_u64(&(proc->waitStart), 0);
}
+ /* Should have consumed exactly the expected amount of fast-path memory. */
+ Assert(fpPtr = fpEndPtr);
+
/*
* Save pointers to the blocks of PGPROC structures reserved for auxiliary
* processes and prepared transactions.
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index e394f1419ad..7f5eada9d45 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -4190,6 +4190,9 @@ PostgresSingleUserMain(int argc, char *argv[],
/* Initialize MaxBackends */
InitializeMaxBackends();
+ /* Initialize size of fast-path lock cache. */
+ InitializeFastPathLocks();
+
/*
* Give preloaded libraries a chance to request additional shared memory.
*/
diff --git a/src/backend/utils/init/postinit.c b/src/backend/utils/init/postinit.c
index 3b50ce19a2c..a024b1151d0 100644
--- a/src/backend/utils/init/postinit.c
+++ b/src/backend/utils/init/postinit.c
@@ -558,6 +558,40 @@ InitializeMaxBackends(void)
}
/*
+ * Initialize the number of fast-path lock slots in PGPROC.
+ *
+ * This must be called after modules have had the chance to alter GUCs in
+ * shared_preload_libraries and before shared memory size is determined.
+ *
+ * The default max_locks_per_xact=64 means 4 groups by default.
+ *
+ * We allow anything between 1 and 1024 groups, with the usual power-of-2
+ * logic. The 1 is the "old" size with only 16 slots, 1024 is an arbitrary
+ * limit (matching max_locks_per_xact = 16k). Values over 1024 are unlikely
+ * to be beneficial - there are bottlenecks we'll hit way before that.
+ */
+void
+InitializeFastPathLocks(void)
+{
+ /* Should be initialized only once. */
+ Assert(FastPathLockGroupsPerBackend == 0);
+
+ /* we need at least one group */
+ FastPathLockGroupsPerBackend = 1;
+
+ while (FastPathLockGroupsPerBackend < FP_LOCK_GROUPS_PER_BACKEND_MAX)
+ {
+ /* stop once we exceed max_locks_per_xact */
+ if (FastPathLockGroupsPerBackend * FP_LOCK_SLOTS_PER_GROUP >= max_locks_per_xact)
+ break;
+
+ FastPathLockGroupsPerBackend *= 2;
+ }
+
+ Assert(FastPathLockGroupsPerBackend <= FP_LOCK_GROUPS_PER_BACKEND_MAX);
+}
+
+/*
* Early initialization of a backend (either standalone or under postmaster).
* This happens even before InitPostgres.
*
diff --git a/src/include/miscadmin.h b/src/include/miscadmin.h
index 25348e71eb9..e26d108a470 100644
--- a/src/include/miscadmin.h
+++ b/src/include/miscadmin.h
@@ -475,6 +475,7 @@ extern PGDLLIMPORT ProcessingMode Mode;
#define INIT_PG_OVERRIDE_ROLE_LOGIN 0x0004
extern void pg_split_opts(char **argv, int *argcp, const char *optstr);
extern void InitializeMaxBackends(void);
+extern void InitializeFastPathLocks(void);
extern void InitPostgres(const char *in_dbname, Oid dboid,
const char *username, Oid useroid,
bits32 flags,
diff --git a/src/include/storage/proc.h b/src/include/storage/proc.h
index deeb06c9e01..ebcf0ad4036 100644
--- a/src/include/storage/proc.h
+++ b/src/include/storage/proc.h
@@ -78,12 +78,17 @@ struct XidCache
#define PROC_XMIN_FLAGS (PROC_IN_VACUUM | PROC_IN_SAFE_IC)
/*
- * We allow a small number of "weak" relation locks (AccessShareLock,
+ * We allow a limited number of "weak" relation locks (AccessShareLock,
* RowShareLock, RowExclusiveLock) to be recorded in the PGPROC structure
- * rather than the main lock table. This eases contention on the lock
- * manager LWLocks. See storage/lmgr/README for additional details.
+ * (or rather in shared memory referenced from PGPROC) rather than the main
+ * lock table. This eases contention on the lock manager LWLocks. See
+ * storage/lmgr/README for additional details.
*/
-#define FP_LOCK_SLOTS_PER_BACKEND 16
+extern PGDLLIMPORT int FastPathLockGroupsPerBackend;
+
+#define FP_LOCK_GROUPS_PER_BACKEND_MAX 1024
+#define FP_LOCK_SLOTS_PER_GROUP 16 /* don't change */
+#define FP_LOCK_SLOTS_PER_BACKEND (FP_LOCK_SLOTS_PER_GROUP * FastPathLockGroupsPerBackend)
/*
* Flags for PGPROC.delayChkptFlags
@@ -292,8 +297,8 @@ struct PGPROC
/* Lock manager data, recording fast-path locks taken by this backend. */
LWLock fpInfoLock; /* protects per-backend fast-path state */
- uint64 fpLockBits; /* lock modes held for each fast-path slot */
- Oid fpRelId[FP_LOCK_SLOTS_PER_BACKEND]; /* slots for rel oids */
+ uint64 *fpLockBits; /* lock modes held for each fast-path slot */
+ Oid *fpRelId; /* slots for rel oids */
bool fpVXIDLock; /* are we holding a fast-path VXID lock? */
LocalTransactionId fpLocalTransactionId; /* lxid for fast-path VXID
* lock */
generated by cgit v1.2.3 (git 2.25.1) at 2025-05-29 21:14:01 +0000