On Mon, Dec 5, 2016 at 3:12 PM, Robert Haas <robertmh...@gmail.com> wrote:
> On Thu, Dec 1, 2016 at 6:35 AM, Thomas Munro
> <thomas.mu...@enterprisedb.com> wrote:
>> On Sat, Nov 26, 2016 at 1:55 AM, Thomas Munro
>> <thomas.mu...@enterprisedb.com> wrote:
>>> Here's a new version to apply on top of dsa-v7.patch.
>>
>> Here's a version to go with dsa-v8.patch.
>
> Thomas has spent a fair amount of time beating me up off-list about
> the fact that we have no way to recycle LWLock tranche IDs, and I've
> spent a fair amount of time trying to defend that decision, but it's
> really a problem here. This is all well and good the way it's written
> provided that there's only one parallel context in existence at a
> time, but should that number ever exceed 1, which it can, then the
> tranche's array_base will be incorrect for LWLocks in one or the other
> tranche.
>
> That *almost* doesn't matter. If you're not compiling with dtrace or
> LOCK_DEBUG or LWLOCK_STATS, you'll be fine. And if you are compiling
> with one of those things, I believe the consequences will be no worse
> than an occasional nonsensical lock ID. It's halfway tempting to just
> accept that as a known wart, but, uggh, that sucks.
>
> It's a bit hard to come up with a better alternative.
After thinking about this some more, I realized that the problem here
boils down to T_ID() not being smart enough to cope with multiple
instances of the same tranche at different base addresses. We can
either make it more complicated so that it can do that, or (drum roll,
please!) get rid of it altogether. I don't think making it more
complicated is very desirable, because I think that we end up
computing T_ID() for every lock acquisition and release whenever
--enable-dtrace is used, even if dtrace is not actually in use. And
the usefulness of T_ID() for debugging is pretty marginal, with one
important exception, which is that currently T_ID() is used to
distinguish between individual LWLocks in the main tranche. So here's
my proposal:
1. Give every LWLock in the main tranche a separate tranche ID. This
has been previously proposed, so it's not a revolutionary concept.
2. Always identify LWLocks in pg_stat_activity only by tranche ID,
never offset within the tranche, not even for the main tranche. This
results in pg_stat_activity saying "LWLock" rather than either
"LWLockNamed" or "LWLockTranche", which is a user-visible behavior
change but not AFAICS a very upsetting one.
3. Change the dtrace probes that currently pass both T_NAME() and
T_ID() to pass only T_NAME(). This is a minor loss of information for
dtrace, but in view of (1) it's not a very significant loss.
4. Change LOCK_DEBUG and LWLOCK_STATS output that identifies locks
using T_NAME() and T_ID() to instead identify them by T_NAME() and the
pointer address. Since these are only developer debugging facilities
not intended for production builds, I think it's OK to expose the
pointer address, and it's arguably MORE useful to do so than to expose
an offset into an array with an unknown base address.
5. Remove T_ID() from the can't-happen elog() in LWLockRelease().
6. Remove T_ID() itself. And then, since that's the only client of
array_base/array_stride, remove those too. And then, since there's
nothing left in LWLockTranche except for the tranche name, get rid of
the whole structure, simplifying a whole bunch of code all over the
system.
Patch implementing all of this attached. There's further
simplification that could be done here -- with array_stride gone, we
could do more at compile time rather than run-time -- but I think that
can be left for another day.
The overall result of this is a considerable savings of code:
doc/src/sgml/monitoring.sgml | 52 ++++-----
src/backend/access/transam/slru.c | 6 +-
src/backend/access/transam/xlog.c | 9 +-
src/backend/postmaster/pgstat.c | 10 +-
src/backend/replication/logical/origin.c | 8 +-
src/backend/replication/slot.c | 8 +-
src/backend/storage/buffer/buf_init.c | 16 +--
src/backend/storage/ipc/procarray.c | 9 +-
src/backend/storage/lmgr/lwlock.c | 175 ++++++++++---------------------
src/backend/utils/mmgr/dsa.c | 15 +--
src/backend/utils/probes.d | 16 +--
src/include/access/slru.h | 1 -
src/include/pgstat.h | 3 +-
src/include/storage/lwlock.h | 45 ++------
14 files changed, 112 insertions(+), 261 deletions(-)
It also noticeably reduces the number of bytes of machine code
generated for lwlock.c:
[rhaas pgsql]$ size src/backend/storage/lmgr/lwlock.o # echo master
__TEXT __DATA __OBJC others dec hex
11815 3360 0 46430 61605 f0a5
[rhaas pgsql]$ size src/backend/storage/lmgr/lwlock.o # echo lwlock
__TEXT __DATA __OBJC others dec hex
11199 3264 0 45487 59950 ea2e
That's better than a 5% reduction in the code size of a very hot
module just by removing something that almost nobody uses or cares
about. That's with --enable-dtrace but without --enable-cassert.
Thoughts?
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 128ee13..5b58d2e 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -646,18 +646,11 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
<itemizedlist>
<listitem>
<para>
- <literal>LWLockNamed</>: The backend is waiting for a specific named
- lightweight lock. Each such lock protects a particular data
- structure in shared memory. <literal>wait_event</> will contain
- the name of the lightweight lock.
- </para>
- </listitem>
- <listitem>
- <para>
- <literal>LWLockTranche</>: The backend is waiting for one of a
- group of related lightweight locks. All locks in the group perform
- a similar function; <literal>wait_event</> will identify the general
- purpose of locks in that group.
+ <literal>LWLock</>: The backend is waiting for a lightweight lock.
+ Each such lock protects a particular data structure in shared memory.
+ <literal>wait_event</> will contain a name identifying the purpose
+ of the lightweight lock. (Some locks have specific names; others
+ are part of a group of locks each with a similar purpose.)
</para>
</listitem>
<listitem>
@@ -825,7 +818,7 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
<tbody>
<row>
- <entry morerows="41"><literal>LWLockNamed</></entry>
+ <entry morerows="57"><literal>LWLock</></entry>
<entry><literal>ShmemIndexLock</></entry>
<entry>Waiting to find or allocate space in shared memory.</entry>
</row>
@@ -1011,7 +1004,6 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
<entry>Waiting to read or update old snapshot control information.</entry>
</row>
<row>
- <entry morerows="15"><literal>LWLockTranche</></entry>
<entry><literal>clog</></entry>
<entry>Waiting for I/O on a clog (transaction status) buffer.</entry>
</row>
@@ -1279,7 +1271,7 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i
pid | wait_event_type | wait_event
------+-----------------+---------------
2540 | Lock | relation
- 6644 | LWLockNamed | ProcArrayLock
+ 6644 | LWLock | ProcArrayLock
(2 rows)
</programlisting>
</para>
@@ -3347,55 +3339,49 @@ SELECT pg_stat_get_backend_pid(s.backendid) AS pid,
</row>
<row>
<entry><literal>lwlock-acquire</literal></entry>
- <entry><literal>(char *, int, LWLockMode)</literal></entry>
+ <entry><literal>(char *, LWLockMode)</literal></entry>
<entry>Probe that fires when an LWLock has been acquired.
arg0 is the LWLock's tranche.
- arg1 is the LWLock's offset within its tranche.
- arg2 is the requested lock mode, either exclusive or shared.</entry>
+ arg1 is the requested lock mode, either exclusive or shared.</entry>
</row>
<row>
<entry><literal>lwlock-release</literal></entry>
- <entry><literal>(char *, int)</literal></entry>
+ <entry><literal>(char *)</literal></entry>
<entry>Probe that fires when an LWLock has been released (but note
that any released waiters have not yet been awakened).
- arg0 is the LWLock's tranche.
- arg1 is the LWLock's offset within its tranche.</entry>
+ arg0 is the LWLock's tranche.</entry>
</row>
<row>
<entry><literal>lwlock-wait-start</literal></entry>
- <entry><literal>(char *, int, LWLockMode)</literal></entry>
+ <entry><literal>(char *, LWLockMode)</literal></entry>
<entry>Probe that fires when an LWLock was not immediately available and
a server process has begun to wait for the lock to become available.
arg0 is the LWLock's tranche.
- arg1 is the LWLock's offset within its tranche.
- arg2 is the requested lock mode, either exclusive or shared.</entry>
+ arg1 is the requested lock mode, either exclusive or shared.</entry>
</row>
<row>
<entry><literal>lwlock-wait-done</literal></entry>
- <entry><literal>(char *, int, LWLockMode)</literal></entry>
+ <entry><literal>(char *, LWLockMode)</literal></entry>
<entry>Probe that fires when a server process has been released from its
wait for an LWLock (it does not actually have the lock yet).
arg0 is the LWLock's tranche.
- arg1 is the LWLock's offset within its tranche.
- arg2 is the requested lock mode, either exclusive or shared.</entry>
+ arg1 is the requested lock mode, either exclusive or shared.</entry>
</row>
<row>
<entry><literal>lwlock-condacquire</literal></entry>
- <entry><literal>(char *, int, LWLockMode)</literal></entry>
+ <entry><literal>(char *, LWLockMode)</literal></entry>
<entry>Probe that fires when an LWLock was successfully acquired when the
caller specified no waiting.
arg0 is the LWLock's tranche.
- arg1 is the LWLock's offset within its tranche.
- arg2 is the requested lock mode, either exclusive or shared.</entry>
+ arg1 is the requested lock mode, either exclusive or shared.</entry>
</row>
<row>
<entry><literal>lwlock-condacquire-fail</literal></entry>
- <entry><literal>(char *, int, LWLockMode)</literal></entry>
+ <entry><literal>(char *, LWLockMode)</literal></entry>
<entry>Probe that fires when an LWLock was not successfully acquired when
the caller specified no waiting.
arg0 is the LWLock's tranche.
- arg1 is the LWLock's offset within its tranche.
- arg2 is the requested lock mode, either exclusive or shared.</entry>
+ arg1 is the requested lock mode, either exclusive or shared.</entry>
</row>
<row>
<entry><literal>lock-wait-start</literal></entry>
diff --git a/src/backend/access/transam/slru.c b/src/backend/access/transam/slru.c
index bbae584..8b95f35 100644
--- a/src/backend/access/transam/slru.c
+++ b/src/backend/access/transam/slru.c
@@ -216,9 +216,6 @@ SimpleLruInit(SlruCtl ctl, const char *name, int nslots, int nlsns,
Assert(strlen(name) + 1 < SLRU_MAX_NAME_LENGTH);
strlcpy(shared->lwlock_tranche_name, name, SLRU_MAX_NAME_LENGTH);
shared->lwlock_tranche_id = tranche_id;
- shared->lwlock_tranche.name = shared->lwlock_tranche_name;
- shared->lwlock_tranche.array_base = shared->buffer_locks;
- shared->lwlock_tranche.array_stride = sizeof(LWLockPadded);
ptr += BUFFERALIGN(offset);
for (slotno = 0; slotno < nslots; slotno++)
@@ -237,7 +234,8 @@ SimpleLruInit(SlruCtl ctl, const char *name, int nslots, int nlsns,
Assert(found);
/* Register SLRU tranche in the main tranches array */
- LWLockRegisterTranche(shared->lwlock_tranche_id, &shared->lwlock_tranche);
+ LWLockRegisterTranche(shared->lwlock_tranche_id,
+ shared->lwlock_tranche_name);
/*
* Initialize the unshared control struct, including directory path. We
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 084401d..aa9ee5a 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -517,7 +517,6 @@ typedef struct XLogCtlInsert
* WAL insertion locks.
*/
WALInsertLockPadded *WALInsertLocks;
- LWLockTranche WALInsertLockTranche;
} XLogCtlInsert;
/*
@@ -4688,7 +4687,7 @@ XLOGShmemInit(void)
/* Initialize local copy of WALInsertLocks and register the tranche */
WALInsertLocks = XLogCtl->Insert.WALInsertLocks;
LWLockRegisterTranche(LWTRANCHE_WAL_INSERT,
- &XLogCtl->Insert.WALInsertLockTranche);
+ "wal_insert");
return;
}
memset(XLogCtl, 0, sizeof(XLogCtlData));
@@ -4711,11 +4710,7 @@ XLOGShmemInit(void)
(WALInsertLockPadded *) allocptr;
allocptr += sizeof(WALInsertLockPadded) * NUM_XLOGINSERT_LOCKS;
- XLogCtl->Insert.WALInsertLockTranche.name = "wal_insert";
- XLogCtl->Insert.WALInsertLockTranche.array_base = WALInsertLocks;
- XLogCtl->Insert.WALInsertLockTranche.array_stride = sizeof(WALInsertLockPadded);
-
- LWLockRegisterTranche(LWTRANCHE_WAL_INSERT, &XLogCtl->Insert.WALInsertLockTranche);
+ LWLockRegisterTranche(LWTRANCHE_WAL_INSERT, "wal_insert");
for (i = 0; i < NUM_XLOGINSERT_LOCKS; i++)
{
LWLockInitialize(&WALInsertLocks[i].l.lock, LWTRANCHE_WAL_INSERT);
diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index c7584cb..61e6a2c 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -3152,11 +3152,8 @@ pgstat_get_wait_event_type(uint32 wait_event_info)
switch (classId)
{
- case PG_WAIT_LWLOCK_NAMED:
- event_type = "LWLockNamed";
- break;
- case PG_WAIT_LWLOCK_TRANCHE:
- event_type = "LWLockTranche";
+ case PG_WAIT_LWLOCK:
+ event_type = "LWLock";
break;
case PG_WAIT_LOCK:
event_type = "Lock";
@@ -3209,8 +3206,7 @@ pgstat_get_wait_event(uint32 wait_event_info)
switch (classId)
{
- case PG_WAIT_LWLOCK_NAMED:
- case PG_WAIT_LWLOCK_TRANCHE:
+ case PG_WAIT_LWLOCK:
event_name = GetLWLockIdentifier(classId, eventId);
break;
case PG_WAIT_LOCK:
diff --git a/src/backend/replication/logical/origin.c b/src/backend/replication/logical/origin.c
index cc2b513..0deec75 100644
--- a/src/backend/replication/logical/origin.c
+++ b/src/backend/replication/logical/origin.c
@@ -143,7 +143,6 @@ typedef struct ReplicationStateOnDisk
typedef struct ReplicationStateCtl
{
int tranche_id;
- LWLockTranche tranche;
ReplicationState states[FLEXIBLE_ARRAY_MEMBER];
} ReplicationStateCtl;
@@ -474,11 +473,6 @@ ReplicationOriginShmemInit(void)
int i;
replication_states_ctl->tranche_id = LWTRANCHE_REPLICATION_ORIGIN;
- replication_states_ctl->tranche.name = "replication_origin";
- replication_states_ctl->tranche.array_base =
- &replication_states[0].lock;
- replication_states_ctl->tranche.array_stride =
- sizeof(ReplicationState);
MemSet(replication_states, 0, ReplicationOriginShmemSize());
@@ -488,7 +482,7 @@ ReplicationOriginShmemInit(void)
}
LWLockRegisterTranche(replication_states_ctl->tranche_id,
- &replication_states_ctl->tranche);
+ "replication_origin");
}
/* ---------------------------------------------------------------------------
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index d8ed005..cf814d1 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -98,8 +98,6 @@ ReplicationSlot *MyReplicationSlot = NULL;
int max_replication_slots = 0; /* the maximum number of replication
* slots */
-static LWLockTranche ReplSlotIOLWLockTranche;
-
static void ReplicationSlotDropAcquired(void);
static void ReplicationSlotDropPtr(ReplicationSlot *slot);
@@ -141,12 +139,8 @@ ReplicationSlotsShmemInit(void)
ShmemInitStruct("ReplicationSlot Ctl", ReplicationSlotsShmemSize(),
&found);
- ReplSlotIOLWLockTranche.name = "replication_slot_io";
- ReplSlotIOLWLockTranche.array_base =
- ((char *) ReplicationSlotCtl) + offsetof(ReplicationSlotCtlData, replication_slots) +offsetof(ReplicationSlot, io_in_progress_lock);
- ReplSlotIOLWLockTranche.array_stride = sizeof(ReplicationSlot);
LWLockRegisterTranche(LWTRANCHE_REPLICATION_SLOT_IO_IN_PROGRESS,
- &ReplSlotIOLWLockTranche);
+ "replication_slot_io");
if (!found)
{
diff --git a/src/backend/storage/buffer/buf_init.c b/src/backend/storage/buffer/buf_init.c
index a4163cf..c507389 100644
--- a/src/backend/storage/buffer/buf_init.c
+++ b/src/backend/storage/buffer/buf_init.c
@@ -21,8 +21,6 @@
BufferDescPadded *BufferDescriptors;
char *BufferBlocks;
LWLockMinimallyPadded *BufferIOLWLockArray = NULL;
-LWLockTranche BufferIOLWLockTranche;
-LWLockTranche BufferContentLWLockTranche;
WritebackContext BackendWritebackContext;
CkptSortItem *CkptBufferIds;
@@ -90,18 +88,8 @@ InitBufferPool(void)
NBuffers * (Size) sizeof(LWLockMinimallyPadded),
&foundIOLocks);
- BufferIOLWLockTranche.name = "buffer_io";
- BufferIOLWLockTranche.array_base = BufferIOLWLockArray;
- BufferIOLWLockTranche.array_stride = sizeof(LWLockMinimallyPadded);
- LWLockRegisterTranche(LWTRANCHE_BUFFER_IO_IN_PROGRESS,
- &BufferIOLWLockTranche);
-
- BufferContentLWLockTranche.name = "buffer_content";
- BufferContentLWLockTranche.array_base =
- ((char *) BufferDescriptors) + offsetof(BufferDesc, content_lock);
- BufferContentLWLockTranche.array_stride = sizeof(BufferDescPadded);
- LWLockRegisterTranche(LWTRANCHE_BUFFER_CONTENT,
- &BufferContentLWLockTranche);
+ LWLockRegisterTranche(LWTRANCHE_BUFFER_IO_IN_PROGRESS, "buffer_io");
+ LWLockRegisterTranche(LWTRANCHE_BUFFER_CONTENT, "buffer_content");
/*
* The array used to sort to-be-checkpointed buffer ids is located in
diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c
index bf38470..0f63755 100644
--- a/src/backend/storage/ipc/procarray.c
+++ b/src/backend/storage/ipc/procarray.c
@@ -106,9 +106,6 @@ static TransactionId *KnownAssignedXids;
static bool *KnownAssignedXidsValid;
static TransactionId latestObservedXid = InvalidTransactionId;
-/* LWLock tranche for backend locks */
-static LWLockTranche ProcLWLockTranche;
-
/*
* If we're in STANDBY_SNAPSHOT_PENDING state, standbySnapshotPendingXmin is
* the highest xid that might still be running that we don't have in
@@ -266,11 +263,7 @@ CreateSharedProcArray(void)
}
/* Register and initialize fields of ProcLWLockTranche */
- ProcLWLockTranche.name = "proc";
- ProcLWLockTranche.array_base = (char *) (ProcGlobal->allProcs) +
- offsetof(PGPROC, backendLock);
- ProcLWLockTranche.array_stride = sizeof(PGPROC);
- LWLockRegisterTranche(LWTRANCHE_PROC, &ProcLWLockTranche);
+ LWLockRegisterTranche(LWTRANCHE_PROC, "proc");
}
/*
diff --git a/src/backend/storage/lmgr/lwlock.c b/src/backend/storage/lmgr/lwlock.c
index 03c4c78..4b381e4 100644
--- a/src/backend/storage/lmgr/lwlock.c
+++ b/src/backend/storage/lmgr/lwlock.c
@@ -108,18 +108,14 @@ extern slock_t *ShmemLock;
#define LW_SHARED_MASK ((uint32) ((1 << 24)-1))
/*
- * This is indexed by tranche ID and stores metadata for all tranches known
+ * This is indexed by tranche ID and stores the names of all tranches known
* to the current backend.
*/
-static LWLockTranche **LWLockTrancheArray = NULL;
+static char **LWLockTrancheArray = NULL;
static int LWLockTranchesAllocated = 0;
#define T_NAME(lock) \
- (LWLockTrancheArray[(lock)->tranche]->name)
-#define T_ID(lock) \
- ((int) ((((char *) lock) - \
- ((char *) LWLockTrancheArray[(lock)->tranche]->array_base)) / \
- LWLockTrancheArray[(lock)->tranche]->array_stride))
+ (LWLockTrancheArray[(lock)->tranche])
/*
* This points to the main array of LWLocks in shared memory. Backends inherit
@@ -127,10 +123,6 @@ static int LWLockTranchesAllocated = 0;
* where we have special measures to pass it down).
*/
LWLockPadded *MainLWLockArray = NULL;
-static LWLockTranche MainLWLockTranche;
-static LWLockTranche BufMappingLWLockTranche;
-static LWLockTranche LockManagerLWLockTranche;
-static LWLockTranche PredicateLockManagerLWLockTranche;
/*
* We use this structure to keep track of locked LWLocks for release
@@ -175,7 +167,7 @@ static inline void LWLockReportWaitEnd(void);
typedef struct lwlock_stats_key
{
int tranche;
- int instance;
+ void *instance;
} lwlock_stats_key;
typedef struct lwlock_stats
@@ -202,32 +194,18 @@ PRINT_LWDEBUG(const char *where, LWLock *lock, LWLockMode mode)
if (Trace_lwlocks)
{
uint32 state = pg_atomic_read_u32(&lock->state);
- int id = T_ID(lock);
-
- if (lock->tranche == 0 && id < NUM_INDIVIDUAL_LWLOCKS)
- ereport(LOG,
- (errhidestmt(true),
- errhidecontext(true),
- errmsg_internal("%d: %s(%s): excl %u shared %u haswaiters %u waiters %u rOK %d",
- MyProcPid,
- where, MainLWLockNames[id],
- (state & LW_VAL_EXCLUSIVE) != 0,
- state & LW_SHARED_MASK,
- (state & LW_FLAG_HAS_WAITERS) != 0,
- pg_atomic_read_u32(&lock->nwaiters),
- (state & LW_FLAG_RELEASE_OK) != 0)));
- else
- ereport(LOG,
- (errhidestmt(true),
- errhidecontext(true),
- errmsg_internal("%d: %s(%s %d): excl %u shared %u haswaiters %u waiters %u rOK %d",
- MyProcPid,
- where, T_NAME(lock), id,
- (state & LW_VAL_EXCLUSIVE) != 0,
- state & LW_SHARED_MASK,
- (state & LW_FLAG_HAS_WAITERS) != 0,
- pg_atomic_read_u32(&lock->nwaiters),
- (state & LW_FLAG_RELEASE_OK) != 0)));
+
+ ereport(LOG,
+ (errhidestmt(true),
+ errhidecontext(true),
+ errmsg_internal("%d: %s(%s %p): excl %u shared %u haswaiters %u waiters %u rOK %d",
+ MyProcPid,
+ where, T_NAME(lock), lock,
+ (state & LW_VAL_EXCLUSIVE) != 0,
+ state & LW_SHARED_MASK,
+ (state & LW_FLAG_HAS_WAITERS) != 0,
+ pg_atomic_read_u32(&lock->nwaiters),
+ (state & LW_FLAG_RELEASE_OK) != 0)));
}
}
@@ -237,20 +215,11 @@ LOG_LWDEBUG(const char *where, LWLock *lock, const char *msg)
/* hide statement & context here, otherwise the log is just too verbose */
if (Trace_lwlocks)
{
- int id = T_ID(lock);
-
- if (lock->tranche == 0 && id < NUM_INDIVIDUAL_LWLOCKS)
- ereport(LOG,
- (errhidestmt(true),
- errhidecontext(true),
- errmsg_internal("%s(%s): %s", where,
- MainLWLockNames[id], msg)));
- else
- ereport(LOG,
- (errhidestmt(true),
- errhidecontext(true),
- errmsg_internal("%s(%s %d): %s", where,
- T_NAME(lock), id, msg)));
+ ereport(LOG,
+ (errhidestmt(true),
+ errhidecontext(true),
+ errmsg_internal("%s(%s %p): %s", where,
+ T_NAME(lock), lock, msg)));
}
}
@@ -315,8 +284,8 @@ print_lwlock_stats(int code, Datum arg)
while ((lwstats = (lwlock_stats *) hash_seq_search(&scan)) != NULL)
{
fprintf(stderr,
- "PID %d lwlock %s %d: shacq %u exacq %u blk %u spindelay %u dequeue self %u\n",
- MyProcPid, LWLockTrancheArray[lwstats->key.tranche]->name,
+ "PID %d lwlock %s %p: shacq %u exacq %u blk %u spindelay %u dequeue self %u\n",
+ MyProcPid, LWLockTrancheArray[lwstats->key.tranche],
lwstats->key.instance, lwstats->sh_acquire_count,
lwstats->ex_acquire_count, lwstats->block_count,
lwstats->spin_delay_count, lwstats->dequeue_self_count);
@@ -342,7 +311,7 @@ get_lwlock_stats_entry(LWLock *lock)
/* Fetch or create the entry. */
key.tranche = lock->tranche;
- key.instance = T_ID(lock);
+ key.instance = lock;
lwstats = hash_search(lwlock_stats_htab, &key, HASH_ENTER, &found);
if (!found)
{
@@ -464,7 +433,7 @@ InitializeLWLocks(void)
/* Initialize all individual LWLocks in main array */
for (id = 0, lock = MainLWLockArray; id < NUM_INDIVIDUAL_LWLOCKS; id++, lock++)
- LWLockInitialize(&lock->lock, LWTRANCHE_MAIN);
+ LWLockInitialize(&lock->lock, id);
/* Initialize buffer mapping LWLocks in main array */
lock = MainLWLockArray + NUM_INDIVIDUAL_LWLOCKS;
@@ -506,10 +475,8 @@ InitializeLWLocks(void)
name = trancheNames;
trancheNames += strlen(request->tranche_name) + 1;
strcpy(name, request->tranche_name);
- tranche->lwLockTranche.name = name;
tranche->trancheId = LWLockNewTrancheId();
- tranche->lwLockTranche.array_base = lock;
- tranche->lwLockTranche.array_stride = sizeof(LWLockPadded);
+ tranche->trancheName = name;
for (j = 0; j < request->num_lwlocks; j++, lock++)
LWLockInitialize(&lock->lock, tranche->trancheId);
@@ -527,39 +494,25 @@ RegisterLWLockTranches(void)
if (LWLockTrancheArray == NULL)
{
- LWLockTranchesAllocated = 32;
- LWLockTrancheArray = (LWLockTranche **)
+ LWLockTranchesAllocated = 64;
+ LWLockTrancheArray = (char **)
MemoryContextAllocZero(TopMemoryContext,
- LWLockTranchesAllocated * sizeof(LWLockTranche *));
+ LWLockTranchesAllocated * sizeof(char *));
Assert(LWLockTranchesAllocated >= LWTRANCHE_FIRST_USER_DEFINED);
}
- MainLWLockTranche.name = "main";
- MainLWLockTranche.array_base = MainLWLockArray;
- MainLWLockTranche.array_stride = sizeof(LWLockPadded);
- LWLockRegisterTranche(LWTRANCHE_MAIN, &MainLWLockTranche);
+ for (i = 0; i < NUM_INDIVIDUAL_LWLOCKS; ++i)
+ LWLockRegisterTranche(i, MainLWLockNames[i]);
- BufMappingLWLockTranche.name = "buffer_mapping";
- BufMappingLWLockTranche.array_base = MainLWLockArray + NUM_INDIVIDUAL_LWLOCKS;
- BufMappingLWLockTranche.array_stride = sizeof(LWLockPadded);
- LWLockRegisterTranche(LWTRANCHE_BUFFER_MAPPING, &BufMappingLWLockTranche);
-
- LockManagerLWLockTranche.name = "lock_manager";
- LockManagerLWLockTranche.array_base = MainLWLockArray + NUM_INDIVIDUAL_LWLOCKS +
- NUM_BUFFER_PARTITIONS;
- LockManagerLWLockTranche.array_stride = sizeof(LWLockPadded);
- LWLockRegisterTranche(LWTRANCHE_LOCK_MANAGER, &LockManagerLWLockTranche);
-
- PredicateLockManagerLWLockTranche.name = "predicate_lock_manager";
- PredicateLockManagerLWLockTranche.array_base = MainLWLockArray + NUM_INDIVIDUAL_LWLOCKS +
- NUM_BUFFER_PARTITIONS + NUM_LOCK_PARTITIONS;
- PredicateLockManagerLWLockTranche.array_stride = sizeof(LWLockPadded);
- LWLockRegisterTranche(LWTRANCHE_PREDICATE_LOCK_MANAGER, &PredicateLockManagerLWLockTranche);
+ LWLockRegisterTranche(LWTRANCHE_BUFFER_MAPPING, "buffer_mapping");
+ LWLockRegisterTranche(LWTRANCHE_LOCK_MANAGER, "lock_manager");
+ LWLockRegisterTranche(LWTRANCHE_PREDICATE_LOCK_MANAGER,
+ "predicate_lock_manager");
/* Register named tranches. */
for (i = 0; i < NamedLWLockTrancheRequests; i++)
LWLockRegisterTranche(NamedLWLockTrancheArray[i].trancheId,
- &NamedLWLockTrancheArray[i].lwLockTranche);
+ NamedLWLockTrancheArray[i].trancheName);
}
/*
@@ -633,7 +586,7 @@ LWLockNewTrancheId(void)
* (TopMemoryContext, static variable, or similar).
*/
void
-LWLockRegisterTranche(int tranche_id, LWLockTranche *tranche)
+LWLockRegisterTranche(int tranche_id, char *tranche_name)
{
Assert(LWLockTrancheArray != NULL);
@@ -645,15 +598,14 @@ LWLockRegisterTranche(int tranche_id, LWLockTranche *tranche)
while (i <= tranche_id)
i *= 2;
- LWLockTrancheArray = (LWLockTranche **)
- repalloc(LWLockTrancheArray,
- i * sizeof(LWLockTranche *));
+ LWLockTrancheArray = (char **)
+ repalloc(LWLockTrancheArray, i * sizeof(char *));
LWLockTranchesAllocated = i;
while (j < LWLockTranchesAllocated)
LWLockTrancheArray[j++] = NULL;
}
- LWLockTrancheArray[tranche_id] = tranche;
+ LWLockTrancheArray[tranche_id] = tranche_name;
}
/*
@@ -729,12 +681,7 @@ LWLockInitialize(LWLock *lock, int tranche_id)
static inline void
LWLockReportWaitStart(LWLock *lock)
{
- int lockId = T_ID(lock);
-
- if (lock->tranche == 0)
- pgstat_report_wait_start(PG_WAIT_LWLOCK_NAMED | (uint16) lockId);
- else
- pgstat_report_wait_start(PG_WAIT_LWLOCK_TRANCHE | lock->tranche);
+ pgstat_report_wait_start(PG_WAIT_LWLOCK | lock->tranche);
}
/*
@@ -752,10 +699,7 @@ LWLockReportWaitEnd(void)
const char *
GetLWLockIdentifier(uint32 classId, uint16 eventId)
{
- if (classId == PG_WAIT_LWLOCK_NAMED)
- return MainLWLockNames[eventId];
-
- Assert(classId == PG_WAIT_LWLOCK_TRANCHE);
+ Assert(classId == PG_WAIT_LWLOCK);
/*
* It is quite possible that user has registered tranche in one of the
@@ -763,10 +707,10 @@ GetLWLockIdentifier(uint32 classId, uint16 eventId)
* all of them, so we can't assume the tranche is registered here.
*/
if (eventId >= LWLockTranchesAllocated ||
- LWLockTrancheArray[eventId]->name == NULL)
+ LWLockTrancheArray[eventId] == NULL)
return "extension";
- return LWLockTrancheArray[eventId]->name;
+ return LWLockTrancheArray[eventId];
}
/*
@@ -1279,7 +1223,7 @@ LWLockAcquire(LWLock *lock, LWLockMode mode)
#endif
LWLockReportWaitStart(lock);
- TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), T_ID(lock), mode);
+ TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), mode);
for (;;)
{
@@ -1301,7 +1245,7 @@ LWLockAcquire(LWLock *lock, LWLockMode mode)
}
#endif
- TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), T_ID(lock), mode);
+ TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), mode);
LWLockReportWaitEnd();
LOG_LWDEBUG("LWLockAcquire", lock, "awakened");
@@ -1310,7 +1254,7 @@ LWLockAcquire(LWLock *lock, LWLockMode mode)
result = false;
}
- TRACE_POSTGRESQL_LWLOCK_ACQUIRE(T_NAME(lock), T_ID(lock), mode);
+ TRACE_POSTGRESQL_LWLOCK_ACQUIRE(T_NAME(lock), mode);
/* Add lock to list of locks held by this backend */
held_lwlocks[num_held_lwlocks].lock = lock;
@@ -1361,14 +1305,14 @@ LWLockConditionalAcquire(LWLock *lock, LWLockMode mode)
RESUME_INTERRUPTS();
LOG_LWDEBUG("LWLockConditionalAcquire", lock, "failed");
- TRACE_POSTGRESQL_LWLOCK_CONDACQUIRE_FAIL(T_NAME(lock), T_ID(lock), mode);
+ TRACE_POSTGRESQL_LWLOCK_CONDACQUIRE_FAIL(T_NAME(lock), mode);
}
else
{
/* Add lock to list of locks held by this backend */
held_lwlocks[num_held_lwlocks].lock = lock;
held_lwlocks[num_held_lwlocks++].mode = mode;
- TRACE_POSTGRESQL_LWLOCK_CONDACQUIRE(T_NAME(lock), T_ID(lock), mode);
+ TRACE_POSTGRESQL_LWLOCK_CONDACQUIRE(T_NAME(lock), mode);
}
return !mustwait;
}
@@ -1440,7 +1384,7 @@ LWLockAcquireOrWait(LWLock *lock, LWLockMode mode)
#endif
LWLockReportWaitStart(lock);
- TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), T_ID(lock), mode);
+ TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), mode);
for (;;)
{
@@ -1458,7 +1402,7 @@ LWLockAcquireOrWait(LWLock *lock, LWLockMode mode)
Assert(nwaiters < MAX_BACKENDS);
}
#endif
- TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), T_ID(lock), mode);
+ TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), mode);
LWLockReportWaitEnd();
LOG_LWDEBUG("LWLockAcquireOrWait", lock, "awakened");
@@ -1488,8 +1432,7 @@ LWLockAcquireOrWait(LWLock *lock, LWLockMode mode)
/* Failed to get lock, so release interrupt holdoff */
RESUME_INTERRUPTS();
LOG_LWDEBUG("LWLockAcquireOrWait", lock, "failed");
- TRACE_POSTGRESQL_LWLOCK_ACQUIRE_OR_WAIT_FAIL(T_NAME(lock), T_ID(lock),
- mode);
+ TRACE_POSTGRESQL_LWLOCK_ACQUIRE_OR_WAIT_FAIL(T_NAME(lock), mode);
}
else
{
@@ -1497,7 +1440,7 @@ LWLockAcquireOrWait(LWLock *lock, LWLockMode mode)
/* Add lock to list of locks held by this backend */
held_lwlocks[num_held_lwlocks].lock = lock;
held_lwlocks[num_held_lwlocks++].mode = mode;
- TRACE_POSTGRESQL_LWLOCK_ACQUIRE_OR_WAIT(T_NAME(lock), T_ID(lock), mode);
+ TRACE_POSTGRESQL_LWLOCK_ACQUIRE_OR_WAIT(T_NAME(lock), mode);
}
return !mustwait;
@@ -1657,8 +1600,7 @@ LWLockWaitForVar(LWLock *lock, uint64 *valptr, uint64 oldval, uint64 *newval)
#endif
LWLockReportWaitStart(lock);
- TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), T_ID(lock),
- LW_EXCLUSIVE);
+ TRACE_POSTGRESQL_LWLOCK_WAIT_START(T_NAME(lock), LW_EXCLUSIVE);
for (;;)
{
@@ -1677,8 +1619,7 @@ LWLockWaitForVar(LWLock *lock, uint64 *valptr, uint64 oldval, uint64 *newval)
}
#endif
- TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), T_ID(lock),
- LW_EXCLUSIVE);
+ TRACE_POSTGRESQL_LWLOCK_WAIT_DONE(T_NAME(lock), LW_EXCLUSIVE);
LWLockReportWaitEnd();
LOG_LWDEBUG("LWLockWaitForVar", lock, "awakened");
@@ -1686,7 +1627,7 @@ LWLockWaitForVar(LWLock *lock, uint64 *valptr, uint64 oldval, uint64 *newval)
/* Now loop back and check the status of the lock again. */
}
- TRACE_POSTGRESQL_LWLOCK_ACQUIRE(T_NAME(lock), T_ID(lock), LW_EXCLUSIVE);
+ TRACE_POSTGRESQL_LWLOCK_ACQUIRE(T_NAME(lock), LW_EXCLUSIVE);
/*
* Fix the process wait semaphore's count for any absorbed wakeups.
@@ -1784,7 +1725,7 @@ LWLockRelease(LWLock *lock)
break;
if (i < 0)
- elog(ERROR, "lock %s %d is not held", T_NAME(lock), T_ID(lock));
+ elog(ERROR, "lock %s is not held", T_NAME(lock));
mode = held_lwlocks[i].mode;
@@ -1829,7 +1770,7 @@ LWLockRelease(LWLock *lock)
LWLockWakeup(lock);
}
- TRACE_POSTGRESQL_LWLOCK_RELEASE(T_NAME(lock), T_ID(lock));
+ TRACE_POSTGRESQL_LWLOCK_RELEASE(T_NAME(lock));
/*
* Now okay to allow cancel/die interrupts.
diff --git a/src/backend/utils/mmgr/dsa.c b/src/backend/utils/mmgr/dsa.c
index abe3f1a..988a297 100644
--- a/src/backend/utils/mmgr/dsa.c
+++ b/src/backend/utils/mmgr/dsa.c
@@ -362,9 +362,6 @@ struct dsa_area
/* Pointer to the control object in shared memory. */
dsa_area_control *control;
- /* The lock tranche for this process. */
- LWLockTranche lwlock_tranche;
-
/* Has the mapping been pinned? */
bool mapping_pinned;
@@ -1207,10 +1204,8 @@ create_internal(void *place, size_t size,
area->mapping_pinned = false;
memset(area->segment_maps, 0, sizeof(dsa_segment_map) * DSA_MAX_SEGMENTS);
area->high_segment_index = 0;
- area->lwlock_tranche.array_base = &area->control->pools[0];
- area->lwlock_tranche.array_stride = sizeof(dsa_area_pool);
- area->lwlock_tranche.name = control->lwlock_tranche_name;
- LWLockRegisterTranche(control->lwlock_tranche_id, &area->lwlock_tranche);
+ LWLockRegisterTranche(control->lwlock_tranche_id,
+ control->lwlock_tranche_name);
LWLockInitialize(&control->lock, control->lwlock_tranche_id);
for (i = 0; i < DSA_NUM_SIZE_CLASSES; ++i)
LWLockInitialize(DSA_SCLASS_LOCK(area, i),
@@ -1267,10 +1262,8 @@ attach_internal(void *place, dsm_segment *segment, dsa_handle handle)
memset(&area->segment_maps[0], 0,
sizeof(dsa_segment_map) * DSA_MAX_SEGMENTS);
area->high_segment_index = 0;
- area->lwlock_tranche.array_base = &area->control->pools[0];
- area->lwlock_tranche.array_stride = sizeof(dsa_area_pool);
- area->lwlock_tranche.name = control->lwlock_tranche_name;
- LWLockRegisterTranche(control->lwlock_tranche_id, &area->lwlock_tranche);
+ LWLockRegisterTranche(control->lwlock_tranche_id,
+ control->lwlock_tranche_name);
/* Set up the segment map for this process's mapping. */
segment_map = &area->segment_maps[0];
diff --git a/src/backend/utils/probes.d b/src/backend/utils/probes.d
index 2f92dfa..adcebe2 100644
--- a/src/backend/utils/probes.d
+++ b/src/backend/utils/probes.d
@@ -28,14 +28,14 @@ provider postgresql {
probe transaction__commit(LocalTransactionId);
probe transaction__abort(LocalTransactionId);
- probe lwlock__acquire(const char *, int, LWLockMode);
- probe lwlock__release(const char *, int);
- probe lwlock__wait__start(const char *, int, LWLockMode);
- probe lwlock__wait__done(const char *, int, LWLockMode);
- probe lwlock__condacquire(const char *, int, LWLockMode);
- probe lwlock__condacquire__fail(const char *, int, LWLockMode);
- probe lwlock__acquire__or__wait(const char *, int, LWLockMode);
- probe lwlock__acquire__or__wait__fail(const char *, int, LWLockMode);
+ probe lwlock__acquire(const char *, LWLockMode);
+ probe lwlock__release(const char *);
+ probe lwlock__wait__start(const char *, LWLockMode);
+ probe lwlock__wait__done(const char *, LWLockMode);
+ probe lwlock__condacquire(const char *, LWLockMode);
+ probe lwlock__condacquire__fail(const char *, LWLockMode);
+ probe lwlock__acquire__or__wait(const char *, LWLockMode);
+ probe lwlock__acquire__or__wait__fail(const char *, LWLockMode);
probe lock__wait__start(unsigned int, unsigned int, unsigned int, unsigned int, unsigned int, LOCKMODE);
probe lock__wait__done(unsigned int, unsigned int, unsigned int, unsigned int, unsigned int, LOCKMODE);
diff --git a/src/include/access/slru.h b/src/include/access/slru.h
index 5fcebc5..ca8ab7b 100644
--- a/src/include/access/slru.h
+++ b/src/include/access/slru.h
@@ -104,7 +104,6 @@ typedef struct SlruSharedData
/* LWLocks */
int lwlock_tranche_id;
- LWLockTranche lwlock_tranche;
char lwlock_tranche_name[SLRU_MAX_NAME_LENGTH];
LWLockPadded *buffer_locks;
} SlruSharedData;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 152ff06..282f8ae 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -715,8 +715,7 @@ typedef enum BackendState
* Wait Classes
* ----------
*/
-#define PG_WAIT_LWLOCK_NAMED 0x01000000U
-#define PG_WAIT_LWLOCK_TRANCHE 0x02000000U
+#define PG_WAIT_LWLOCK 0x01000000U
#define PG_WAIT_LOCK 0x03000000U
#define PG_WAIT_BUFFER_PIN 0x04000000U
#define PG_WAIT_ACTIVITY 0x05000000U
diff --git a/src/include/storage/lwlock.h b/src/include/storage/lwlock.h
index 9a2d869..db1c687 100644
--- a/src/include/storage/lwlock.h
+++ b/src/include/storage/lwlock.h
@@ -25,32 +25,6 @@
struct PGPROC;
/*
- * Prior to PostgreSQL 9.4, every lightweight lock in the system was stored
- * in a single array. For convenience and for compatibility with past
- * releases, we still have a main array, but it's now also permissible to
- * store LWLocks elsewhere in the main shared memory segment or in a dynamic
- * shared memory segment. Each array of lwlocks forms a separate "tranche".
- *
- * It's occasionally necessary to identify a particular LWLock "by name"; e.g.
- * because we wish to report the lock to dtrace. We could store a name or
- * other identifying information in the lock itself, but since it's common
- * to have many nearly-identical locks (e.g. one per buffer) this would end
- * up wasting significant amounts of memory. Instead, each lwlock stores a
- * tranche ID which tells us which array it's part of. Based on that, we can
- * figure out where the lwlock lies within the array using the data structure
- * shown below; the lock is then identified based on the tranche name and
- * computed array index. We need the array stride because the array might not
- * be an array of lwlocks, but rather some larger data structure that includes
- * one or more lwlocks per element.
- */
-typedef struct LWLockTranche
-{
- const char *name;
- void *array_base;
- Size array_stride;
-} LWLockTranche;
-
-/*
* Code outside of lwlock.c should not manipulate the contents of this
* structure directly, but we have to declare it here to allow LWLocks to be
* incorporated into other data structures.
@@ -118,8 +92,8 @@ extern char *MainLWLockNames[];
/* struct for storing named tranche information */
typedef struct NamedLWLockTranche
{
- LWLockTranche lwLockTranche;
int trancheId;
+ char *trancheName;
} NamedLWLockTranche;
extern PGDLLIMPORT NamedLWLockTranche *NamedLWLockTrancheArray;
@@ -199,9 +173,9 @@ extern LWLockPadded *GetNamedLWLockTranche(const char *tranche_name);
* There is another, more flexible method of obtaining lwlocks. First, call
* LWLockNewTrancheId just once to obtain a tranche ID; this allocates from
* a shared counter. Next, each individual process using the tranche should
- * call LWLockRegisterTranche() to associate that tranche ID with appropriate
- * metadata. Finally, LWLockInitialize should be called just once per lwlock,
- * passing the tranche ID as an argument.
+ * call LWLockRegisterTranche() to associate that tranche ID with a name.
+ * Finally, LWLockInitialize should be called just once per lwlock, passing
+ * the tranche ID as an argument.
*
* It may seem strange that each process using the tranche must register it
* separately, but dynamic shared memory segments aren't guaranteed to be
@@ -209,17 +183,18 @@ extern LWLockPadded *GetNamedLWLockTranche(const char *tranche_name);
* registration in the main shared memory segment wouldn't work for that case.
*/
extern int LWLockNewTrancheId(void);
-extern void LWLockRegisterTranche(int tranche_id, LWLockTranche *tranche);
+extern void LWLockRegisterTranche(int tranche_id, char *tranche_name);
extern void LWLockInitialize(LWLock *lock, int tranche_id);
/*
- * We reserve a few predefined tranche IDs. A call to LWLockNewTrancheId
- * will never return a value less than LWTRANCHE_FIRST_USER_DEFINED.
+ * Every tranche ID less than NUM_INDIVIDUAL_LWLOCKS is reserved; also,
+ * we reserve additional tranche IDs for builtin tranches not included in
+ * the set of individual LWLocks. A call to LWLockNewTrancheId will never
+ * return a value less than LWTRANCHE_FIRST_USER_DEFINED.
*/
typedef enum BuiltinTrancheIds
{
- LWTRANCHE_MAIN,
- LWTRANCHE_CLOG_BUFFERS,
+ LWTRANCHE_CLOG_BUFFERS = NUM_INDIVIDUAL_LWLOCKS,
LWTRANCHE_COMMITTS_BUFFERS,
LWTRANCHE_SUBTRANS_BUFFERS,
LWTRANCHE_MXACTOFFSET_BUFFERS,
--
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