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Implement new 'lightweight lock manager' that's intermediate between

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existing lock manager and spinlocks: it understands exclusive vs shared
lock but has few other fancy features.  Replace most uses of spinlocks
with lightweight locks.  All remaining uses of spinlocks have very short
lock hold times (a few dozen instructions), so tweak spinlock backoff
code to work efficiently given this assumption.  All per my proposal on
pghackers 26-Sep-01.
This commit is contained in:
Tom Lane
2001-09-29 04:02:27 +00:00
parent 818fb55ac4
commit 499abb0c0f
46 changed files with 1595 additions and 1355 deletions
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72
src/backend/storage/lmgr/lock.c
View File

@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lock.c,v 1.95 2001/09/27 16:29:12 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lock.c,v 1.96 2001/09/29 04:02:24 tgl Exp $
*
* NOTES
* Outside modules can create a lock table and acquire/release
@@ -78,8 +78,8 @@ static char *lock_mode_names[] =
* TRACE_LOCK_TABLE -- trace locks on this table (oid) unconditionally
* DEBUG_DEADLOCKS -- currently dumps locks at untimely occasions ;)
*
* Furthermore, but in storage/ipc/spin.c:
* TRACE_SPINLOCKS -- trace spinlocks (pretty useless)
* Furthermore, but in storage/lmgr/lwlock.c:
* TRACE_LWLOCKS -- trace lightweight locks (pretty useless)
*
* Define LOCK_DEBUG at compile time to get all these enabled.
* --------
@@ -151,10 +151,6 @@ HOLDER_PRINT(const char *where, const HOLDER *holderP)
#endif /* not LOCK_DEBUG */
SPINLOCK LockMgrLock; /* in Shmem or created in
* CreateSpinlocks() */
/*
* These are to simplify/speed up some bit arithmetic.
*
@@ -230,12 +226,6 @@ LockMethodInit(LOCKMETHODTABLE *lockMethodTable,
/*
* LockMethodTableInit -- initialize a lock table structure
*
* Notes:
* (a) a lock table has four separate entries in the shmem index
* table. This is because every shared hash table and spinlock
* has its name stored in the shmem index at its creation. It
* is wasteful, in this case, but not much space is involved.
*
* NOTE: data structures allocated here are allocated permanently, using
* TopMemoryContext and shared memory. We don't ever release them anyway,
* and in normal multi-backend operation the lock table structures set up
@@ -277,9 +267,9 @@ LockMethodTableInit(char *tabName,
MemoryContextAlloc(TopMemoryContext, sizeof(LOCKMETHODTABLE));
/*
* find/acquire the spinlock for the table
* Lock the LWLock for the table (probably not necessary here)
*/
SpinAcquire(LockMgrLock);
LWLockAcquire(LockMgrLock, LW_EXCLUSIVE);
/*
* allocate a control structure from shared memory or attach to it if
@@ -356,7 +346,7 @@ LockMethodTableInit(char *tabName,
/* init ctl data structures */
LockMethodInit(lockMethodTable, conflictsP, prioP, numModes);
SpinRelease(LockMgrLock);
LWLockRelease(LockMgrLock);
pfree(shmemName);
@@ -464,7 +454,7 @@ LockAcquire(LOCKMETHOD lockmethod, LOCKTAG *locktag,
HTAB *holderTable;
bool found;
LOCK *lock;
SPINLOCK masterLock;
LWLockId masterLock;
LOCKMETHODTABLE *lockMethodTable;
int status;
int myHolding[MAX_LOCKMODES];
@@ -489,7 +479,7 @@ LockAcquire(LOCKMETHOD lockmethod, LOCKTAG *locktag,
masterLock = lockMethodTable->ctl->masterLock;
SpinAcquire(masterLock);
LWLockAcquire(masterLock, LW_EXCLUSIVE);
/*
* Find or create a lock with this tag
@@ -499,7 +489,7 @@ LockAcquire(LOCKMETHOD lockmethod, LOCKTAG *locktag,
HASH_ENTER, &found);
if (!lock)
{
SpinRelease(masterLock);
LWLockRelease(masterLock);
elog(FATAL, "LockAcquire: lock table %d is corrupted", lockmethod);
return FALSE;
}
@@ -544,7 +534,7 @@ LockAcquire(LOCKMETHOD lockmethod, LOCKTAG *locktag,
HASH_ENTER, &found);
if (!holder)
{
SpinRelease(masterLock);
LWLockRelease(masterLock);
elog(FATAL, "LockAcquire: holder table corrupted");
return FALSE;
}
@@ -617,7 +607,7 @@ LockAcquire(LOCKMETHOD lockmethod, LOCKTAG *locktag,
{
GrantLock(lock, holder, lockmode);
HOLDER_PRINT("LockAcquire: owning", holder);
SpinRelease(masterLock);
LWLockRelease(masterLock);
return TRUE;
}
@@ -630,7 +620,7 @@ LockAcquire(LOCKMETHOD lockmethod, LOCKTAG *locktag,
{
GrantLock(lock, holder, lockmode);
HOLDER_PRINT("LockAcquire: my other XID owning", holder);
SpinRelease(masterLock);
LWLockRelease(masterLock);
return TRUE;
}
@@ -677,7 +667,7 @@ LockAcquire(LOCKMETHOD lockmethod, LOCKTAG *locktag,
LOCK_PRINT("LockAcquire: conditional lock failed", lock, lockmode);
Assert((lock->nRequested > 0) && (lock->requested[lockmode] >= 0));
Assert(lock->nGranted <= lock->nRequested);
SpinRelease(masterLock);
LWLockRelease(masterLock);
return FALSE;
}
@@ -719,14 +709,14 @@ LockAcquire(LOCKMETHOD lockmethod, LOCKTAG *locktag,
HOLDER_PRINT("LockAcquire: INCONSISTENT", holder);
LOCK_PRINT("LockAcquire: INCONSISTENT", lock, lockmode);
/* Should we retry ? */
SpinRelease(masterLock);
LWLockRelease(masterLock);
return FALSE;
}
HOLDER_PRINT("LockAcquire: granted", holder);
LOCK_PRINT("LockAcquire: granted", lock, lockmode);
}
SpinRelease(masterLock);
LWLockRelease(masterLock);
return status == STATUS_OK;
}
@@ -879,7 +869,7 @@ GrantLock(LOCK *lock, HOLDER *holder, LOCKMODE lockmode)
* Caller must have set MyProc->heldLocks to reflect locks already held
* on the lockable object by this process (under all XIDs).
*
* The locktable spinlock must be held at entry.
* The locktable's masterLock must be held at entry.
*/
static int
WaitOnLock(LOCKMETHOD lockmethod, LOCKMODE lockmode,
@@ -925,7 +915,7 @@ WaitOnLock(LOCKMETHOD lockmethod, LOCKMODE lockmode,
* needed, will happen in xact cleanup (see above for motivation).
*/
LOCK_PRINT("WaitOnLock: aborting on lock", lock, lockmode);
SpinRelease(lockMethodTable->ctl->masterLock);
LWLockRelease(lockMethodTable->ctl->masterLock);
elog(ERROR, "deadlock detected");
/* not reached */
}
@@ -998,7 +988,7 @@ LockRelease(LOCKMETHOD lockmethod, LOCKTAG *locktag,
TransactionId xid, LOCKMODE lockmode)
{
LOCK *lock;
SPINLOCK masterLock;
LWLockId masterLock;
bool found;
LOCKMETHODTABLE *lockMethodTable;
HOLDER *holder;
@@ -1023,7 +1013,7 @@ LockRelease(LOCKMETHOD lockmethod, LOCKTAG *locktag,
}
masterLock = lockMethodTable->ctl->masterLock;
SpinAcquire(masterLock);
LWLockAcquire(masterLock, LW_EXCLUSIVE);
/*
* Find a lock with this tag
@@ -1038,14 +1028,14 @@ LockRelease(LOCKMETHOD lockmethod, LOCKTAG *locktag,
*/
if (!lock)
{
SpinRelease(masterLock);
LWLockRelease(masterLock);
elog(NOTICE, "LockRelease: locktable corrupted");
return FALSE;
}
if (!found)
{
SpinRelease(masterLock);
LWLockRelease(masterLock);
elog(NOTICE, "LockRelease: no such lock");
return FALSE;
}
@@ -1065,7 +1055,7 @@ LockRelease(LOCKMETHOD lockmethod, LOCKTAG *locktag,
HASH_FIND_SAVE, &found);
if (!holder || !found)
{
SpinRelease(masterLock);
LWLockRelease(masterLock);
#ifdef USER_LOCKS
if (!found && lockmethod == USER_LOCKMETHOD)
elog(NOTICE, "LockRelease: no lock with this tag");
@@ -1084,7 +1074,7 @@ LockRelease(LOCKMETHOD lockmethod, LOCKTAG *locktag,
{
HOLDER_PRINT("LockRelease: WRONGTYPE", holder);
Assert(holder->holding[lockmode] >= 0);
SpinRelease(masterLock);
LWLockRelease(masterLock);
elog(NOTICE, "LockRelease: you don't own a lock of type %s",
lock_mode_names[lockmode]);
return FALSE;
@@ -1139,7 +1129,7 @@ LockRelease(LOCKMETHOD lockmethod, LOCKTAG *locktag,
&found);
if (!lock || !found)
{
SpinRelease(masterLock);
LWLockRelease(masterLock);
elog(NOTICE, "LockRelease: remove lock, table corrupted");
return FALSE;
}
@@ -1167,7 +1157,7 @@ LockRelease(LOCKMETHOD lockmethod, LOCKTAG *locktag,
HASH_REMOVE_SAVED, &found);
if (!holder || !found)
{
SpinRelease(masterLock);
LWLockRelease(masterLock);
elog(NOTICE, "LockRelease: remove holder, table corrupted");
return FALSE;
}
@@ -1179,7 +1169,7 @@ LockRelease(LOCKMETHOD lockmethod, LOCKTAG *locktag,
if (wakeupNeeded)
ProcLockWakeup(lockMethodTable, lock);
SpinRelease(masterLock);
LWLockRelease(masterLock);
return TRUE;
}
@@ -1201,7 +1191,7 @@ LockReleaseAll(LOCKMETHOD lockmethod, PROC *proc,
SHM_QUEUE *procHolders = &(proc->procHolders);
HOLDER *holder;
HOLDER *nextHolder;
SPINLOCK masterLock;
LWLockId masterLock;
LOCKMETHODTABLE *lockMethodTable;
int i,
numLockModes;
@@ -1225,7 +1215,7 @@ LockReleaseAll(LOCKMETHOD lockmethod, PROC *proc,
numLockModes = lockMethodTable->ctl->numLockModes;
masterLock = lockMethodTable->ctl->masterLock;
SpinAcquire(masterLock);
LWLockAcquire(masterLock, LW_EXCLUSIVE);
holder = (HOLDER *) SHMQueueNext(procHolders, procHolders,
offsetof(HOLDER, procLink));
@@ -1321,7 +1311,7 @@ LockReleaseAll(LOCKMETHOD lockmethod, PROC *proc,
&found);
if (!holder || !found)
{
SpinRelease(masterLock);
LWLockRelease(masterLock);
elog(NOTICE, "LockReleaseAll: holder table corrupted");
return FALSE;
}
@@ -1340,7 +1330,7 @@ LockReleaseAll(LOCKMETHOD lockmethod, PROC *proc,
HASH_REMOVE, &found);
if (!lock || !found)
{
SpinRelease(masterLock);
LWLockRelease(masterLock);
elog(NOTICE, "LockReleaseAll: cannot remove lock from HTAB");
return FALSE;
}
@@ -1352,7 +1342,7 @@ next_item:
holder = nextHolder;
}
SpinRelease(masterLock);
LWLockRelease(masterLock);
#ifdef LOCK_DEBUG
if (lockmethod == USER_LOCKMETHOD ? Trace_userlocks : Trace_locks)