Sync process names between ps and pg_stat_activity

Remove gratuitous differences in the process names shown in
pg_stat_activity.backend_type and the ps output.
Reviewed-by: Takayuki Tsunakawa <tsunakawa.takay@jp.fujitsu.com>

doc/src/sgml/monitoring.sgml

@@ -49,11 +49,11 @@
 <screen>
 $ ps auxww | grep ^postgres
 postgres  15551  0.0  0.1  57536  7132 pts/0    S    18:02   0:00 postgres -i
-postgres  15554  0.0  0.0  57536  1184 ?        Ss   18:02   0:00 postgres: writer process
-postgres  15555  0.0  0.0  57536   916 ?        Ss   18:02   0:00 postgres: checkpointer process
-postgres  15556  0.0  0.0  57536   916 ?        Ss   18:02   0:00 postgres: wal writer process
-postgres  15557  0.0  0.0  58504  2244 ?        Ss   18:02   0:00 postgres: autovacuum launcher process
-postgres  15558  0.0  0.0  17512  1068 ?        Ss   18:02   0:00 postgres: stats collector process
+postgres  15554  0.0  0.0  57536  1184 ?        Ss   18:02   0:00 postgres: background writer
+postgres  15555  0.0  0.0  57536   916 ?        Ss   18:02   0:00 postgres: checkpointer
+postgres  15556  0.0  0.0  57536   916 ?        Ss   18:02   0:00 postgres: walwriter
+postgres  15557  0.0  0.0  58504  2244 ?        Ss   18:02   0:00 postgres: autovacuum launcher
+postgres  15558  0.0  0.0  17512  1068 ?        Ss   18:02   0:00 postgres: stats collector
 postgres  15582  0.0  0.0  58772  3080 ?        Ss   18:04   0:00 postgres: joe runbug 127.0.0.1 idle
 postgres  15606  0.0  0.0  58772  3052 ?        Ss   18:07   0:00 postgres: tgl regression [local] SELECT waiting
 postgres  15610  0.0  0.0  58772  3056 ?        Ss   18:07   0:00 postgres: tgl regression [local] idle in transaction
@@ -102,7 +102,7 @@ $ psql -c 'SHOW cluster_name'
 (1 row)
 
 $ ps aux|grep server1
-postgres   27093  0.0  0.0  30096  2752 ?        Ss   11:34   0:00 postgres: server1: writer process
+postgres   27093  0.0  0.0  30096  2752 ?        Ss   11:34   0:00 postgres: server1: background writer
 ...
 </screen>
   </para>

src/backend/bootstrap/bootstrap.c

@@ -321,19 +321,19 @@ AuxiliaryProcessMain(int argc, char *argv[])
 		switch (MyAuxProcType)
 		{
 			case StartupProcess:
-				statmsg = "startup process";
+				statmsg = pgstat_get_backend_desc(B_STARTUP);
 				break;
 			case BgWriterProcess:
-				statmsg = "writer process";
+				statmsg = pgstat_get_backend_desc(B_BG_WRITER);
 				break;
 			case CheckpointerProcess:
-				statmsg = "checkpointer process";
+				statmsg = pgstat_get_backend_desc(B_CHECKPOINTER);
 				break;
 			case WalWriterProcess:
-				statmsg = "wal writer process";
+				statmsg = pgstat_get_backend_desc(B_WAL_WRITER);
 				break;
 			case WalReceiverProcess:
-				statmsg = "wal receiver process";
+				statmsg = pgstat_get_backend_desc(B_WAL_RECEIVER);
 				break;
 			default:
 				statmsg = "??? process";

src/backend/postmaster/autovacuum.c

@@ -436,7 +436,7 @@ AutoVacLauncherMain(int argc, char *argv[])
 	am_autovacuum_launcher = true;
 
 	/* Identify myself via ps */
-	init_ps_display("autovacuum launcher process", "", "", "");
+	init_ps_display(pgstat_get_backend_desc(B_AUTOVAC_LAUNCHER), "", "", "");
 
 	ereport(DEBUG1,
 			(errmsg("autovacuum launcher started")));
@@ -1519,7 +1519,7 @@ AutoVacWorkerMain(int argc, char *argv[])
 	am_autovacuum_worker = true;
 
 	/* Identify myself via ps */
-	init_ps_display("autovacuum worker process", "", "", "");
+	init_ps_display(pgstat_get_backend_desc(B_AUTOVAC_WORKER), "", "", "");
 
 	SetProcessingMode(InitProcessing);
 

src/backend/postmaster/pgarch.c

@@ -236,7 +236,7 @@ PgArchiverMain(int argc, char *argv[])
 	/*
 	 * Identify myself via ps
 	 */
-	init_ps_display("archiver process", "", "", "");
+	init_ps_display("archiver", "", "", "");
 
 	pgarch_MainLoop();
 

src/backend/postmaster/pgstat.c

@@ -4224,7 +4224,7 @@ PgstatCollectorMain(int argc, char *argv[])
 	/*
 	 * Identify myself via ps
 	 */
-	init_ps_display("stats collector process", "", "", "");
+	init_ps_display("stats collector", "", "", "");
 
 	/*
 	 * Read in existing stats files or initialize the stats to zero.

src/backend/postmaster/postmaster.c

@@ -4266,14 +4266,14 @@ BackendInitialize(Port *port)
 	 *
 	 * For a walsender, the ps display is set in the following form:
 	 *
-	 * postgres: wal sender process <user> <host> <activity>
+	 * postgres: walsender <user> <host> <activity>
 	 *
-	 * To achieve that, we pass "wal sender process" as username and username
+	 * To achieve that, we pass "walsender" as username and username
 	 * as dbname to init_ps_display(). XXX: should add a new variant of
 	 * init_ps_display() to avoid abusing the parameters like this.
 	 */
 	if (am_walsender)
-		init_ps_display("wal sender process", port->user_name, remote_ps_data,
+		init_ps_display(pgstat_get_backend_desc(B_WAL_SENDER), port->user_name, remote_ps_data,
 						update_process_title ? "authentication" : "");
 	else
 		init_ps_display(port->user_name, port->database_name, remote_ps_data,

src/backend/postmaster/syslogger.c

@@ -173,7 +173,7 @@ SysLoggerMain(int argc, char *argv[])
 
 	am_syslogger = true;
 
-	init_ps_display("logger process", "", "", "");
+	init_ps_display("logger", "", "", "");
 
 	/*
 	 * If we restarted, our stderr is already redirected into our own input