pg_wait_sampling.profile_pid setting to collect profile in not per-proccess manner.

Alexander Korotkov · Alexander Korotkov · commit d4d9dadf7a7e · 2016-10-04T16:43:40.000+03:00
diff --git a/README.md b/README.md
@@ -109,11 +109,17 @@ GUCs.
 | pg_wait_sampling.history_size   | int4      | Size of history in-memory ring buffer       |          5000 |
 | pg_wait_sampling.history_period | int4      | Period for history sampling in milliseconds |            10 |
 | pg_wait_sampling.profile_period | int4      | Period for profile sampling in milliseconds |            10 |
+| pg_wait_sampling.profile_pid    | int4      | Whether profile should be per pid           |          true |
 
-These GUCs are allowed to be changed by superuser. Also, they are placed into
-shared memory. Thus, they could be changed from any backend and affects worker
+If pg\_wait\_sampling.profile\_pid is set to false, sampling profile wouldn't be
+collected in per-process manner.  In this case the value of pid could would
+be always zero and corresponding row contain samples among all the processes.
+
+These GUCs are allowed to be changed by superuser.  Also, they are placed into
+shared memory.  Thus, they could be changed from any backend and affects worker
 runtime.
 
+
 See
 [PostgreSQL documentation](http://www.postgresql.org/docs/devel/static/monitoring-stats.html#WAIT-EVENT-TABLE)
 for list of possible wait events.
diff --git a/collector.c b/collector.c
@@ -138,7 +138,7 @@ get_next_observation(History *observations)
  */
 static void
 probe_waits(History *observations, HTAB *profile_hash,
-			bool write_history, bool write_profile)
+			bool write_history, bool write_profile, bool profile_pid)
 {
 	int			i,
 				newSize;
@@ -178,6 +178,9 @@ probe_waits(History *observations, HTAB *profile_hash,
 			ProfileItem	   *profileItem;
 			bool			found;
 
+			if (!profile_pid)
+				item.pid = 0;
+
 			profileItem = (ProfileItem *) hash_search(profile_hash, &item, HASH_ENTER, &found);
 			if (found)
 				profileItem->count++;
@@ -325,7 +328,7 @@ collector_main(Datum main_arg)
 		if (write_history || write_profile)
 		{
 			probe_waits(&observations, profile_hash,
-						write_history, write_profile);
+						write_history, write_profile, collector_hdr->profilePid);
 
 			if (write_history)
 			{
diff --git a/pg_wait_sampling.c b/pg_wait_sampling.c
@@ -75,6 +75,14 @@ shmem_int_guc_check_hook(int *newval, void **extra, GucSource source)
 	return true;
 }
 
+static bool
+shmem_bool_guc_check_hook(bool *newval, void **extra, GucSource source)
+{
+	if (UsedShmemSegAddr == NULL)
+		return false;
+	return true;
+}
+
 /*
  * This union allows us to mix the numerous different types of structs
  * that we are organizing.
@@ -100,7 +108,8 @@ setup_gucs()
 				i;
 	bool		history_size_found = false,
 				history_period_found = false,
-				profile_period_found = false;
+				profile_period_found = false,
+				profile_pid_found = false;
 
 	guc_vars = get_guc_variables();
 	numOpts = GetNumConfigOptions();
@@ -131,6 +140,12 @@ setup_gucs()
 			var->integer.variable = &collector_hdr->profilePeriod;
 			collector_hdr->profilePeriod = 10;
 		}
+		else if (!strcmp(name, "pg_wait_sampling.profile_pid"))
+		{
+			profile_pid_found = true;
+			var->_bool.variable = &collector_hdr->profilePid;
+			collector_hdr->profilePid = true;
+		}
 	}
 
 	if (!history_size_found)
@@ -151,7 +166,14 @@ setup_gucs()
 				&collector_hdr->profilePeriod, 10, 1, INT_MAX,
 				PGC_SUSET, 0, shmem_int_guc_check_hook, NULL, NULL);
 
-	if (history_size_found || history_period_found || profile_period_found)
+	if (!profile_pid_found)
+		DefineCustomBoolVariable("pg_wait_sampling.profile_pid",
+				"Sets whether profile should be collected per pid.", NULL,
+				&collector_hdr->profilePid, true,
+				PGC_SUSET, 0, shmem_bool_guc_check_hook, NULL, NULL);
+
+	if (history_size_found || history_period_found
+		|| profile_period_found || profile_pid_found)
 		ProcessConfigFile(PGC_SIGHUP);
 }
 
diff --git a/pg_wait_sampling.h b/pg_wait_sampling.h
@@ -62,6 +62,7 @@ typedef struct
 	int				historySize;
 	int				historyPeriod;
 	int				profilePeriod;
+	bool			profilePid;
 } CollectorShmqHeader;
 
 /* pg_wait_sampling.c */
