Code review for log_lock_waits patch. Don't try to issue log messages from

within a signal handler (this might be safe given the relatively narrow code
range in which the interrupt is enabled, but it seems awfully risky); do issue
more informative log messages that tell what is being waited for and the exact
length of the wait; minor other code cleanup.  Greg Stark and Tom Lane

doc/src/sgml/config.sgml

-<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.126 2007/06/07 19:19:56 tgl Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.127 2007/06/19 20:13:21 tgl Exp $ -->
 
 <chapter Id="runtime-config">
   <title>Server Configuration</title>
@@ -2947,7 +2947,7 @@ SELECT * FROM parent WHERE key = 2400;
       </indexterm>
       <listitem>
        <para>
-        Controls whether a log message is produced when a statement waits
+        Controls whether a log message is produced when a session waits
         longer than <xref linkend="guc-deadlock-timeout"> to acquire a
         lock.  This is useful in determining if lock waits are causing
         poor performance.  The default is <literal>off</>.
@@ -4084,11 +4084,18 @@ dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir'
         wasted in needless deadlock checks, but slows down reporting of
         real deadlock errors. The default is one second (<literal>1s</>),
         which is probably about the smallest value you would want in
-        practice.  Set <xref linkend="guc-log-lock-waits"> to log deadlock
-        checks.  On a heavily loaded server you might want to raise it.
+        practice. On a heavily loaded server you might want to raise it.
         Ideally the setting should exceed your typical transaction time,
-        so as to improve the odds that a lock will be released before the
-        waiter decides to check for deadlock.
+        so as to improve the odds that a lock will be released before
+        the waiter decides to check for deadlock.
+       </para>
+
+       <para>
+        When <xref linkend="guc-log-lock-waits"> is set,
+        this parameter also determines the length of time to wait before
+        a log message is issued about the lock wait.  If you are trying
+        to investigate locking delays you might want to set a shorter than
+        normal <varname>deadlock_timeout</varname>.
        </para>
       </listitem>
      </varlistentry>

src/backend/storage/lmgr/deadlock.c

@@ -12,7 +12,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/storage/lmgr/deadlock.c,v 1.47 2007/04/20 20:15:52 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/storage/lmgr/deadlock.c,v 1.48 2007/06/19 20:13:21 tgl Exp $
  *
  *	Interface:
  *
@@ -25,8 +25,8 @@
  */
 #include "postgres.h"
 
-#include "lib/stringinfo.h"
 #include "miscadmin.h"
+#include "storage/lmgr.h"
 #include "storage/proc.h"
 #include "utils/memutils.h"
 
@@ -117,8 +117,9 @@ static int	nDeadlockDetails;
  * allocation of working memory for DeadLockCheck.	We do this per-backend
  * since there's no percentage in making the kernel do copy-on-write
  * inheritance of workspace from the postmaster.  We want to allocate the
- * space at startup because the deadlock checker might be invoked when there's
- * no free memory left.
+ * space at startup because (a) the deadlock checker might be invoked when
+ * there's no free memory left, and (b) the checker is normally run inside a
+ * signal handler, which is a very dangerous place to invoke palloc from.
  */
 void
 InitDeadLockChecking(void)
@@ -184,17 +185,17 @@ InitDeadLockChecking(void)
  *
  * This code looks for deadlocks involving the given process.  If any
  * are found, it tries to rearrange lock wait queues to resolve the
- * deadlock.  If resolution is impossible, return TRUE --- the caller
- * is then expected to abort the given proc's transaction.
+ * deadlock.  If resolution is impossible, return DS_HARD_DEADLOCK ---
+ * the caller is then expected to abort the given proc's transaction.
  *
- * Caller must already have locked all partitions of the lock tables,
- * so standard error logging/reporting code is handled by caller.
+ * Caller must already have locked all partitions of the lock tables.
  *
  * On failure, deadlock details are recorded in deadlockDetails[] for
  * subsequent printing by DeadLockReport().  That activity is separate
- * because we don't want to do it while holding all those LWLocks.
+ * because (a) we don't want to do it while holding all those LWLocks,
+ * and (b) we are typically invoked inside a signal handler.
  */
-DeadlockState
+DeadLockState
 DeadLockCheck(PGPROC *proc)
 {
 	int			i,
@@ -205,11 +206,6 @@ DeadLockCheck(PGPROC *proc)
 	nPossibleConstraints = 0;
 	nWaitOrders = 0;
 
-#ifdef LOCK_DEBUG
-	if (Debug_deadlocks)
-		DumpAllLocks();
-#endif
-
 	/* Search for deadlocks and possible fixes */
 	if (DeadLockCheckRecurse(proc))
 	{
@@ -256,10 +252,11 @@ DeadLockCheck(PGPROC *proc)
 		ProcLockWakeup(GetLocksMethodTable(lock), lock);
 	}
 
+	/* Return code tells caller if we had to escape a deadlock or not */
 	if (nWaitOrders > 0)
 		return DS_SOFT_DEADLOCK;
 	else
-		return DS_DEADLOCK_NOT_FOUND;
+		return DS_NO_DEADLOCK;
 }
 
 /*
@@ -833,82 +830,7 @@ PrintLockQueue(LOCK *lock, const char *info)
 #endif
 
 /*
- * Append a description of a lockable object to buf.
- *
- * XXX probably this should be exported from lmgr.c or some such place.
- * Ideally we would print names for the numeric values, but that requires
- * getting locks on system tables, which might cause problems.
- */
-static void
-DescribeLockTag(StringInfo buf, const LOCKTAG *lock)
-{
-	switch (lock->locktag_type)
-	{
-		case LOCKTAG_RELATION:
-			appendStringInfo(buf,
-							 _("relation %u of database %u"),
-							 lock->locktag_field2,
-							 lock->locktag_field1);
-			break;
-		case LOCKTAG_RELATION_EXTEND:
-			appendStringInfo(buf,
-							 _("extension of relation %u of database %u"),
-							 lock->locktag_field2,
-							 lock->locktag_field1);
-			break;
-		case LOCKTAG_PAGE:
-			appendStringInfo(buf,
-							 _("page %u of relation %u of database %u"),
-							 lock->locktag_field3,
-							 lock->locktag_field2,
-							 lock->locktag_field1);
-			break;
-		case LOCKTAG_TUPLE:
-			appendStringInfo(buf,
-							 _("tuple (%u,%u) of relation %u of database %u"),
-							 lock->locktag_field3,
-							 lock->locktag_field4,
-							 lock->locktag_field2,
-							 lock->locktag_field1);
-			break;
-		case LOCKTAG_TRANSACTION:
-			appendStringInfo(buf,
-							 _("transaction %u"),
-							 lock->locktag_field1);
-			break;
-		case LOCKTAG_OBJECT:
-			appendStringInfo(buf,
-							 _("object %u of class %u of database %u"),
-							 lock->locktag_field3,
-							 lock->locktag_field2,
-							 lock->locktag_field1);
-			break;
-		case LOCKTAG_USERLOCK:
-			/* reserved for old contrib code, now on pgfoundry */
-			appendStringInfo(buf,
-							 _("user lock [%u,%u,%u]"),
-							 lock->locktag_field1,
-							 lock->locktag_field2,
-							 lock->locktag_field3);
-			break;
-		case LOCKTAG_ADVISORY:
-			appendStringInfo(buf,
-							 _("advisory lock [%u,%u,%u,%u]"),
-							 lock->locktag_field1,
-							 lock->locktag_field2,
-							 lock->locktag_field3,
-							 lock->locktag_field4);
-			break;
-		default:
-			appendStringInfo(buf,
-							 _("unrecognized locktag type %d"),
-							 lock->locktag_type);
-			break;
-	}
-}
-
-/*
- * Report a detected DS_HARD_DEADLOCK, with available details.
+ * Report a detected deadlock, with available details.
  */
 void
 DeadLockReport(void)

src/backend/storage/lmgr/lmgr.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/storage/lmgr/lmgr.c,v 1.90 2007/01/05 22:19:38 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/storage/lmgr/lmgr.c,v 1.91 2007/06/19 20:13:21 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -635,3 +635,79 @@ LockTagIsTemp(const LOCKTAG *tag)
 	}
 	return false;				/* default case */
 }
+
+
+/*
+ * Append a description of a lockable object to buf.
+ *
+ * Ideally we would print names for the numeric values, but that requires
+ * getting locks on system tables, which might cause problems since this is
+ * typically used to report deadlock situations.
+ */
+void
+DescribeLockTag(StringInfo buf, const LOCKTAG *tag)
+{
+	switch (tag->locktag_type)
+	{
+		case LOCKTAG_RELATION:
+			appendStringInfo(buf,
+							 _("relation %u of database %u"),
+							 tag->locktag_field2,
+							 tag->locktag_field1);
+			break;
+		case LOCKTAG_RELATION_EXTEND:
+			appendStringInfo(buf,
+							 _("extension of relation %u of database %u"),
+							 tag->locktag_field2,
+							 tag->locktag_field1);
+			break;
+		case LOCKTAG_PAGE:
+			appendStringInfo(buf,
+							 _("page %u of relation %u of database %u"),
+							 tag->locktag_field3,
+							 tag->locktag_field2,
+							 tag->locktag_field1);
+			break;
+		case LOCKTAG_TUPLE:
+			appendStringInfo(buf,
+							 _("tuple (%u,%u) of relation %u of database %u"),
+							 tag->locktag_field3,
+							 tag->locktag_field4,
+							 tag->locktag_field2,
+							 tag->locktag_field1);
+			break;
+		case LOCKTAG_TRANSACTION:
+			appendStringInfo(buf,
+							 _("transaction %u"),
+							 tag->locktag_field1);
+			break;
+		case LOCKTAG_OBJECT:
+			appendStringInfo(buf,
+							 _("object %u of class %u of database %u"),
+							 tag->locktag_field3,
+							 tag->locktag_field2,
+							 tag->locktag_field1);
+			break;
+		case LOCKTAG_USERLOCK:
+			/* reserved for old contrib code, now on pgfoundry */
+			appendStringInfo(buf,
+							 _("user lock [%u,%u,%u]"),
+							 tag->locktag_field1,
+							 tag->locktag_field2,
+							 tag->locktag_field3);
+			break;
+		case LOCKTAG_ADVISORY:
+			appendStringInfo(buf,
+							 _("advisory lock [%u,%u,%u,%u]"),
+							 tag->locktag_field1,
+							 tag->locktag_field2,
+							 tag->locktag_field3,
+							 tag->locktag_field4);
+			break;
+		default:
+			appendStringInfo(buf,
+							 _("unrecognized locktag type %d"),
+							 tag->locktag_type);
+			break;
+	}
+}

src/backend/storage/lmgr/proc.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/storage/lmgr/proc.c,v 1.188 2007/04/16 18:29:53 alvherre Exp $
+ *	  $PostgreSQL: pgsql/src/backend/storage/lmgr/proc.c,v 1.189 2007/06/19 20:13:21 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -40,6 +40,7 @@
 #include "miscadmin.h"
 #include "postmaster/autovacuum.h"
 #include "storage/ipc.h"
+#include "storage/lmgr.h"
 #include "storage/proc.h"
 #include "storage/procarray.h"
 #include "storage/spin.h"
@@ -72,8 +73,12 @@ static LOCALLOCK *lockAwaited = NULL;
 /* Mark these volatile because they can be changed by signal handler */
 static volatile bool statement_timeout_active = false;
 static volatile bool deadlock_timeout_active = false;
+static volatile DeadLockState deadlock_state = DS_NOT_YET_CHECKED;
 volatile bool cancel_from_timeout = false;
 
+/* timeout_start_time is set when log_lock_waits is true */
+static TimestampTz timeout_start_time;
+
 /* statement_fin_time is valid only if statement_timeout_active is true */
 static TimestampTz statement_fin_time;
 
@@ -837,6 +842,9 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
 	 */
 	LWLockRelease(partitionLock);
 
+	/* Reset deadlock_state before enabling the signal handler */
+	deadlock_state = DS_NOT_YET_CHECKED;
+
 	/*
 	 * Set timer so we can wake up after awhile and check for a deadlock. If a
 	 * deadlock is detected, the handler releases the process's semaphore and
@@ -869,6 +877,60 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
 	do
 	{
 		PGSemaphoreLock(&MyProc->sem, true);
+
+		/*
+		 * If awoken after the deadlock check interrupt has run, and
+		 * log_lock_waits is on, then report about the wait.
+		 */
+		if (log_lock_waits)
+		{
+			switch (deadlock_state)
+			{
+				case DS_NOT_YET_CHECKED:
+					/* Spurious wakeup as described above */
+					break; 
+				case DS_NO_DEADLOCK:
+				case DS_SOFT_DEADLOCK:
+				{
+					StringInfoData buf;
+					const char *modename;
+					long		secs;
+					int			usecs;
+					long		msecs;
+
+					initStringInfo(&buf);
+					DescribeLockTag(&buf, &locallock->tag.lock);
+					modename = GetLockmodeName(locallock->tag.lock.locktag_lockmethodid,
+											   lockmode);
+					TimestampDifference(timeout_start_time,
+										GetCurrentTimestamp(),
+										&secs, &usecs);
+					msecs = secs * 1000 + usecs / 1000;
+					usecs = usecs % 1000;
+
+					if (deadlock_state == DS_SOFT_DEADLOCK)
+						ereport(LOG,
+								(errmsg("deadlock for %s on %s avoided by rearranging queue order after %ld.%03d ms",
+										modename, buf.data,
+										msecs, usecs)));
+					else if (MyProc->waitStatus == STATUS_WAITING)
+						ereport(LOG,
+								(errmsg("process %d still waiting for %s on %s after %ld.%03d ms",
+										MyProcPid, modename, buf.data,
+										msecs, usecs)));
+					else
+						ereport(LOG,
+								(errmsg("process %d acquired %s on %s after %ld.%03d ms",
+										MyProcPid, modename, buf.data,
+										msecs, usecs)));
+					pfree(buf.data);
+					break;
+				}
+				case DS_HARD_DEADLOCK:
+					/* ERROR will be reported below, so no message here */
+					break; 
+			}
+		}
 	} while (MyProc->waitStatus == STATUS_WAITING);
 
 	/*
@@ -1011,14 +1073,17 @@ ProcLockWakeup(LockMethod lockMethodTable, LOCK *lock)
  * We only get to this routine if we got SIGALRM after DeadlockTimeout
  * while waiting for a lock to be released by some other process.  Look
  * to see if there's a deadlock; if not, just return and continue waiting.
+ * (But signal ProcSleep to log a message, if log_lock_waits is true.)
  * If we have a real deadlock, remove ourselves from the lock's wait queue
  * and signal an error to ProcSleep.
+ *
+ * NB: this is run inside a signal handler, so be very wary about what is done
+ * here or in called routines.
  */
 static void
 CheckDeadLock(void)
 {
 	int			i;
-	DeadlockState deadlock_state = DS_DEADLOCK_NOT_FOUND;
 
 	/*
 	 * Acquire exclusive lock on the entire shared lock data structures. Must
@@ -1044,22 +1109,31 @@ CheckDeadLock(void)
 	 * This is quicker than checking our semaphore's state, since no kernel
 	 * call is needed, and it is safe because we hold the lock partition lock.
 	 */
-	if (MyProc->links.prev != INVALID_OFFSET &&
-		MyProc->links.next != INVALID_OFFSET)
-		deadlock_state = DeadLockCheck(MyProc);
-	
+	if (MyProc->links.prev == INVALID_OFFSET ||
+		MyProc->links.next == INVALID_OFFSET)
+		goto check_done;
+
+#ifdef LOCK_DEBUG
+	if (Debug_deadlocks)
+		DumpAllLocks();
+#endif
+
+	/* Run the deadlock check, and set deadlock_state for use by ProcSleep */
+	deadlock_state = DeadLockCheck(MyProc);
+
 	if (deadlock_state == DS_HARD_DEADLOCK)
 	{
 		/*
 		 * Oops.  We have a deadlock.
 		 *
-		 * Get this process out of wait state.	(Note: we could do this more
-		 * efficiently by relying on lockAwaited, but use this coding to preserve
-		 * the flexibility to kill some other transaction than the one detecting
-		 * the deadlock.)
+		 * Get this process out of wait state. (Note: we could do this more
+		 * efficiently by relying on lockAwaited, but use this coding to
+		 * preserve the flexibility to kill some other transaction than the
+		 * one detecting the deadlock.)
 		 *
 		 * RemoveFromWaitQueue sets MyProc->waitStatus to STATUS_ERROR, so
-		 * ProcSleep will report an error after we return from the signal handler.
+		 * ProcSleep will report an error after we return from the signal
+		 * handler.
 		 */
 		Assert(MyProc->waitLock != NULL);
 		RemoveFromWaitQueue(MyProc, LockTagHashCode(&(MyProc->waitLock->tag)));
@@ -1071,50 +1145,35 @@ CheckDeadLock(void)
 		PGSemaphoreUnlock(&MyProc->sem);
 
 		/*
-		 * We're done here.  Transaction abort caused by the error that ProcSleep
-		 * will raise will cause any other locks we hold to be released, thus
-		 * allowing other processes to wake up; we don't need to do that here.
-		 * NOTE: an exception is that releasing locks we hold doesn't consider the
-		 * possibility of waiters that were blocked behind us on the lock we just
-		 * failed to get, and might now be wakable because we're not in front of
-		 * them anymore.  However, RemoveFromWaitQueue took care of waking up any
-		 * such processes.
+		 * We're done here.  Transaction abort caused by the error that
+		 * ProcSleep will raise will cause any other locks we hold to be
+		 * released, thus allowing other processes to wake up; we don't need
+		 * to do that here.  NOTE: an exception is that releasing locks we
+		 * hold doesn't consider the possibility of waiters that were blocked
+		 * behind us on the lock we just failed to get, and might now be
+		 * wakable because we're not in front of them anymore.  However,
+		 * RemoveFromWaitQueue took care of waking up any such processes.
 		 */
 	}
+	else if (log_lock_waits)
+	{
+		/*
+		 * Unlock my semaphore so that the interrupted ProcSleep() call can
+		 * print the log message (we daren't do it here because we are inside
+		 * a signal handler).  It will then sleep again until someone
+		 * releases the lock.
+		 */
+		PGSemaphoreUnlock(&MyProc->sem);
+	}
 
 	/*
 	 * Release locks acquired at head of routine.  Order is not critical, so
 	 * do it back-to-front to avoid waking another CheckDeadLock instance
 	 * before it can get all the locks.
 	 */
+check_done:
 	for (i = NUM_LOCK_PARTITIONS; --i >= 0;)
 		LWLockRelease(FirstLockMgrLock + i);
-
-	/*
-	 * Issue any log messages requested.
-	 *
-	 * Deadlock ERROR messages are issued as part of transaction abort, so 
-	 * these messages should not raise error states intentionally.
-	 */
-	if (log_lock_waits)
-	{
-		switch (deadlock_state)
-		{
-			case DS_SOFT_DEADLOCK:
-				ereport(LOG,
-					(errmsg("deadlock avoided by rearranging lock order")));
-				break;
-			case DS_DEADLOCK_NOT_FOUND:
-				ereport(LOG,
-					(errmsg("statement waiting for lock for at least %d ms",
-								DeadlockTimeout)));
-				break;
-			case DS_HARD_DEADLOCK:
-				break;	/* ERROR message handled during abort */
-			default:
-				break;
-		}
-	}
 }
 
 
@@ -1211,8 +1270,8 @@ enable_sig_alarm(int delayms, bool is_statement_timeout)
 		 * to the state variables.	The deadlock checker may get run earlier
 		 * than normal, but that does no harm.
 		 */
-		fin_time = GetCurrentTimestamp();
-		fin_time = TimestampTzPlusMilliseconds(fin_time, delayms);
+		timeout_start_time = GetCurrentTimestamp();
+		fin_time = TimestampTzPlusMilliseconds(timeout_start_time, delayms);
 		deadlock_timeout_active = true;
 		if (fin_time >= statement_fin_time)
 			return true;
@@ -1221,6 +1280,9 @@ enable_sig_alarm(int delayms, bool is_statement_timeout)
 	{
 		/* Begin deadlock timeout with no statement-level timeout */
 		deadlock_timeout_active = true;
+		/* GetCurrentTimestamp can be expensive, so only do it if we must */
+		if (log_lock_waits)
+			timeout_start_time = GetCurrentTimestamp();
 	}
 
 	/* If we reach here, okay to set the timer interrupt */

src/backend/utils/misc/guc.c

@@ -10,7 +10,7 @@
  * Written by Peter Eisentraut <peter_e@gmx.net>.
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.398 2007/06/18 10:02:57 mha Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.399 2007/06/19 20:13:22 tgl Exp $
  *
  *--------------------------------------------------------------------
  */
@@ -825,13 +825,14 @@ static struct config_bool ConfigureNamesBool[] =
 #endif
 
 	{
-		{"log_lock_waits", PGC_SIGHUP, LOGGING_WHAT,
-			gettext_noop("Logs long lock wait events."),
+		{"log_lock_waits", PGC_SUSET, LOGGING_WHAT,
+			gettext_noop("Logs long lock waits."),
 			NULL
 		},
 		&log_lock_waits,
 		false, NULL, NULL
 	},
+
 	{
 		{"log_hostname", PGC_SIGHUP, LOGGING_WHAT,
 			gettext_noop("Logs the host name in the connection logs."),

src/include/storage/lmgr.h

@@ -7,13 +7,14 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/storage/lmgr.h,v 1.57 2007/01/05 22:19:58 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/storage/lmgr.h,v 1.58 2007/06/19 20:13:22 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
 #ifndef LMGR_H
 #define LMGR_H
 
+#include "lib/stringinfo.h"
 #include "storage/lock.h"
 #include "utils/rel.h"
 
@@ -69,4 +70,7 @@ extern void UnlockSharedObject(Oid classid, Oid objid, uint16 objsubid,
 /* Knowledge about which locktags describe temp objects */
 extern bool LockTagIsTemp(const LOCKTAG *tag);
 
+/* Describe a locktag for error messages */
+extern void DescribeLockTag(StringInfo buf, const LOCKTAG *tag);
+
 #endif   /* LMGR_H */

src/include/storage/lock.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/storage/lock.h,v 1.105 2007/05/30 16:16:32 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/storage/lock.h,v 1.106 2007/06/19 20:13:22 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -397,10 +397,12 @@ typedef enum
 /* Deadlock states identified by DeadLockCheck() */
 typedef enum
 {
-	DS_DEADLOCK_NOT_FOUND,		/* no deadlock found within database server */
-	DS_SOFT_DEADLOCK,			/* deadlock, but lock queues rearrangeable */
+	DS_NOT_YET_CHECKED,			/* no deadlock check has run yet */
+	DS_NO_DEADLOCK,				/* no deadlock detected */
+	DS_SOFT_DEADLOCK,			/* deadlock avoided by queue rearrangement */
 	DS_HARD_DEADLOCK			/* deadlock, no way out but ERROR */
-} DeadlockState;
+} DeadLockState;
+
 
 /*
  * The lockmgr's shared hash tables are partitioned to reduce contention.
@@ -449,7 +451,7 @@ extern void lock_twophase_postcommit(TransactionId xid, uint16 info,
 extern void lock_twophase_postabort(TransactionId xid, uint16 info,
 						void *recdata, uint32 len);
 
-extern DeadlockState DeadLockCheck(PGPROC *proc);
+extern DeadLockState DeadLockCheck(PGPROC *proc);
 extern void DeadLockReport(void);
 extern void RememberSimpleDeadLock(PGPROC *proc1,
 					   LOCKMODE lockmode,