On Tue, Dec 27, 2016 at 9:28 PM, Thomas Munro
<thomas.mu...@enterprisedb.com> wrote:
> On Wed, Dec 28, 2016 at 11:57 AM, Thomas Munro
> <thomas.mu...@enterprisedb.com> wrote:
>> But I'm starting to think that the best way might be to do BOTH of the
>> things I said in my previous message: make dsa.c register on
>> create/attach and also unregister before detaching iff the name was
>> supplied at creation time for the benefit of extension writers, but
>> make it not do anything at all about tranche name
>> registration/unregistration if NULL was passed in at create time.
>> Then register this particular tranche (LWTRANCHE_PARALLEL_QUERY_DSA)
>> in every process in RegisterLWLockTranches. That way, you'd get a
>> useful name in pg_stat_activity for other backends that are running
>> parallel queries if they are ever waiting for these locks (unlikely
>> but interesting to know abotu if it happens).
>
> Maybe something like the attached.
Now that array_base and array_stride are gone, I don't see any reason
why the DSA machinery needs to be aware of tranche names at all. So I
propose to rip all that out, as in the attached.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
diff --git a/src/backend/executor/execParallel.c b/src/backend/executor/execParallel.c
index 821f3e9..86d9fb5 100644
--- a/src/backend/executor/execParallel.c
+++ b/src/backend/executor/execParallel.c
@@ -486,7 +486,6 @@ ExecInitParallelPlan(PlanState *planstate, EState *estate, int nworkers)
shm_toc_insert(pcxt->toc, PARALLEL_KEY_DSA, area_space);
pei->area = dsa_create_in_place(area_space, dsa_minsize,
LWTRANCHE_PARALLEL_QUERY_DSA,
- "parallel_query_dsa",
pcxt->seg);
}
diff --git a/src/backend/storage/lmgr/lwlock.c b/src/backend/storage/lmgr/lwlock.c
index f4be4b4..1cf0684 100644
--- a/src/backend/storage/lmgr/lwlock.c
+++ b/src/backend/storage/lmgr/lwlock.c
@@ -508,6 +508,8 @@ RegisterLWLockTranches(void)
LWLockRegisterTranche(LWTRANCHE_LOCK_MANAGER, "lock_manager");
LWLockRegisterTranche(LWTRANCHE_PREDICATE_LOCK_MANAGER,
"predicate_lock_manager");
+ LWLockRegisterTranche(LWTRANCHE_PARALLEL_QUERY_DSA,
+ "parallel_query_dsa");
/* Register named tranches. */
for (i = 0; i < NamedLWLockTrancheRequests; i++)
diff --git a/src/backend/utils/mmgr/dsa.c b/src/backend/utils/mmgr/dsa.c
index 200749f..6069b0c 100644
--- a/src/backend/utils/mmgr/dsa.c
+++ b/src/backend/utils/mmgr/dsa.c
@@ -326,7 +326,6 @@ typedef struct
Size freed_segment_counter;
/* The LWLock tranche ID. */
int lwlock_tranche_id;
- char lwlock_tranche_name[DSA_MAXLEN];
/* The general lock (protects everything except object pools). */
LWLock lock;
} dsa_area_control;
@@ -405,7 +404,7 @@ static void unlink_segment(dsa_area *area, dsa_segment_map *segment_map);
static dsa_segment_map *get_best_segment(dsa_area *area, Size npages);
static dsa_segment_map *make_new_segment(dsa_area *area, Size requested_pages);
static dsa_area *create_internal(void *place, size_t size,
- int tranche_id, const char *tranche_name,
+ int tranche_id,
dsm_handle control_handle,
dsm_segment *control_segment);
static dsa_area *attach_internal(void *place, dsm_segment *segment,
@@ -419,12 +418,10 @@ static void check_for_freed_segments(dsa_area *area);
* We can't allocate a LWLock tranche_id within this function, because tranche
* IDs are a scarce resource; there are only 64k available, using low numbers
* when possible matters, and we have no provision for recycling them. So,
- * we require the caller to provide one. The caller must also provide the
- * tranche name, so that we can distinguish LWLocks belonging to different
- * DSAs.
+ * we require the caller to provide one.
*/
dsa_area *
-dsa_create(int tranche_id, const char *tranche_name)
+dsa_create(int tranche_id)
{
dsm_segment *segment;
dsa_area *area;
@@ -446,7 +443,7 @@ dsa_create(int tranche_id, const char *tranche_name)
/* Create a new DSA area with the control objet in this segment. */
area = create_internal(dsm_segment_address(segment),
DSA_INITIAL_SEGMENT_SIZE,
- tranche_id, tranche_name,
+ tranche_id,
dsm_segment_handle(segment), segment);
/* Clean up when the control segment detaches. */
@@ -474,12 +471,11 @@ dsa_create(int tranche_id, const char *tranche_name)
*/
dsa_area *
dsa_create_in_place(void *place, size_t size,
- int tranche_id, const char *tranche_name,
- dsm_segment *segment)
+ int tranche_id, dsm_segment *segment)
{
dsa_area *area;
- area = create_internal(place, size, tranche_id, tranche_name,
+ area = create_internal(place, size, tranche_id,
DSM_HANDLE_INVALID, NULL);
/*
@@ -1139,7 +1135,7 @@ dsa_minimum_size(void)
*/
static dsa_area *
create_internal(void *place, size_t size,
- int tranche_id, const char *tranche_name,
+ int tranche_id,
dsm_handle control_handle,
dsm_segment *control_segment)
{
@@ -1192,7 +1188,6 @@ create_internal(void *place, size_t size,
control->refcnt = 1;
control->freed_segment_counter = 0;
control->lwlock_tranche_id = tranche_id;
- strlcpy(control->lwlock_tranche_name, tranche_name, DSA_MAXLEN);
/*
* Create the dsa_area object that this backend will use to access the
@@ -1204,8 +1199,6 @@ 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;
- 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),
@@ -1262,8 +1255,6 @@ 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;
- 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/include/utils/dsa.h b/src/include/utils/dsa.h
index 0aca58f..bb634e7 100644
--- a/src/include/utils/dsa.h
+++ b/src/include/utils/dsa.h
@@ -90,10 +90,9 @@ typedef dsm_handle dsa_handle;
extern void dsa_startup(void);
-extern dsa_area *dsa_create(int tranche_id, const char *tranche_name);
+extern dsa_area *dsa_create(int tranche_id);
extern dsa_area *dsa_create_in_place(void *place, Size size,
- int tranche_id, const char *tranche_name,
- dsm_segment *segment);
+ int tranche_id, dsm_segment *segment);
extern dsa_area *dsa_attach(dsa_handle handle);
extern dsa_area *dsa_attach_in_place(void *place, dsm_segment *segment);
extern void dsa_release_in_place(void *place);
--
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