Here is a proposed solution that splits bgw_name into bgw_type and
bgw_name_extra. bgw_type shows up in pg_stat_activity.backend_type.
Uses of application_name are removed, because they are no longer
necessary to identity the process type.
This code appears to be buggy because I sometimes get NULL results of
the backend_type lookup, implying that it couldn't find the background
worker slot. This needs another look.
--
Peter Eisentraut http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
From 45444b3362e8d00e998fae195023b8a55d96a005 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <pete...@gmx.net>
Date: Tue, 30 May 2017 22:59:19 -0400
Subject: [PATCH] Split background worker name into type and name
Remove background worker structure field bgw_name and add two new fields
bgw_type and bgw_name_extra. The bgw_type field is intended to be set
to the same value for all workers of the same type, so they can be
grouped in pg_stat_activity, for example. The bgw_name_extra field can
be any suffix that is specific to the individual worker. So bgw_type +
bgw_name_extra is the old bgw_name.
The backend_type column in pg_stat_activity now shows bgw_type for a
background worker. The ps listing and some log messages no longer call
out that a process is a "background worker" but just show the bgw_type.
That way, being a background worker is effectively an implementation
detail now that is not shown to the user.
Don't set application_name in logical replication launcher or worker
anymore. Those processes can now be identified using the mechanisms
described above instead.
---
doc/src/sgml/bgworker.sgml | 17 +++++++++---
src/backend/access/transam/parallel.c | 3 ++-
src/backend/postmaster/bgworker.c | 42 ++++++++++++++++--------------
src/backend/postmaster/postmaster.c | 16 +++++-------
src/backend/replication/logical/launcher.c | 15 +++++------
src/backend/replication/logical/worker.c | 4 ---
src/backend/utils/adt/pgstatfuncs.c | 29 +++++++++++++++++++--
src/include/postmaster/bgworker.h | 3 ++-
src/test/modules/test_shm_mq/setup.c | 2 +-
src/test/modules/worker_spi/worker_spi.c | 17 +++++++-----
10 files changed, 92 insertions(+), 56 deletions(-)
diff --git a/doc/src/sgml/bgworker.sgml b/doc/src/sgml/bgworker.sgml
index b422323081..0a89a5044b 100644
--- a/doc/src/sgml/bgworker.sgml
+++ b/doc/src/sgml/bgworker.sgml
@@ -50,7 +50,8 @@ <title>Background Worker Processes</title>
typedef void (*bgworker_main_type)(Datum main_arg);
typedef struct BackgroundWorker
{
- char bgw_name[BGW_MAXLEN];
+ char bgw_type[BGW_MAXLEN];
+ char bgw_name_extra[BGW_MAXLEN];
int bgw_flags;
BgWorkerStartTime bgw_start_time;
int bgw_restart_time; /* in seconds, or BGW_NEVER_RESTART */
@@ -64,8 +65,18 @@ <title>Background Worker Processes</title>
</para>
<para>
- <structfield>bgw_name</> is a string to be used in log messages, process
- listings and similar contexts.
+ <structfield>bgw_type</> is a string to be used in log messages, process
+ listings and similar contexts. It should be the same for all background
+ workers of the same type, so that it is possible to group such workers in a
+ process listing, for example.
+ </para>
+
+ <para>
+ <structfield>bgw_name_extra</> is a string that is appended
+ to <structfield>bgw_type</structfield> in some contexts such as process
+ listings. Unlike <structfield>bgw_type</structfield>, it can contain
+ information that is particular to this process. The string, if not empty,
+ should normally start with a space or other separator.
</para>
<para>
diff --git a/src/backend/access/transam/parallel.c
b/src/backend/access/transam/parallel.c
index 2dad3e8a65..fbdcf2da31 100644
--- a/src/backend/access/transam/parallel.c
+++ b/src/backend/access/transam/parallel.c
@@ -436,7 +436,8 @@ LaunchParallelWorkers(ParallelContext *pcxt)
/* Configure a worker. */
memset(&worker, 0, sizeof(worker));
- snprintf(worker.bgw_name, BGW_MAXLEN, "parallel worker for PID %d",
+ snprintf(worker.bgw_type, BGW_MAXLEN, "parallel worker");
+ snprintf(worker.bgw_name_extra, BGW_MAXLEN, " for PID %d",
MyProcPid);
worker.bgw_flags =
BGWORKER_SHMEM_ACCESS | BGWORKER_BACKEND_DATABASE_CONNECTION
diff --git a/src/backend/postmaster/bgworker.c
b/src/backend/postmaster/bgworker.c
index c3454276bf..65318a5fb8 100644
--- a/src/backend/postmaster/bgworker.c
+++ b/src/backend/postmaster/bgworker.c
@@ -342,8 +342,10 @@ BackgroundWorkerStateChange(void)
* Copy strings in a paranoid way. If shared memory is
corrupted, the
* source data might not even be NUL-terminated.
*/
- ascii_safe_strlcpy(rw->rw_worker.bgw_name,
- slot->worker.bgw_name,
BGW_MAXLEN);
+ ascii_safe_strlcpy(rw->rw_worker.bgw_type,
+ slot->worker.bgw_type,
BGW_MAXLEN);
+ ascii_safe_strlcpy(rw->rw_worker.bgw_name_extra,
+ slot->worker.bgw_name_extra,
BGW_MAXLEN);
ascii_safe_strlcpy(rw->rw_worker.bgw_library_name,
slot->worker.bgw_library_name, BGW_MAXLEN);
ascii_safe_strlcpy(rw->rw_worker.bgw_function_name,
@@ -389,9 +391,10 @@ BackgroundWorkerStateChange(void)
rw->rw_terminate = false;
/* Log it! */
- ereport(DEBUG1,
- (errmsg("registering background worker \"%s\"",
- rw->rw_worker.bgw_name)));
+ elog(DEBUG1,
+ "registering background worker \"%s%s\"",
+ rw->rw_worker.bgw_type,
+ rw->rw_worker.bgw_name_extra);
slist_push_head(&BackgroundWorkerList, &rw->rw_lnode);
}
@@ -421,9 +424,10 @@ ForgetBackgroundWorker(slist_mutable_iter *cur)
slot->in_use = false;
- ereport(DEBUG1,
- (errmsg("unregistering background worker \"%s\"",
- rw->rw_worker.bgw_name)));
+ elog(DEBUG1,
+ "unregistering background worker \"%s%s\"",
+ rw->rw_worker.bgw_type,
+ rw->rw_worker.bgw_name_extra);
slist_delete_current(cur);
free(rw);
@@ -588,7 +592,7 @@ SanityCheckBackgroundWorker(BackgroundWorker *worker, int
elevel)
ereport(elevel,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("background worker \"%s\": must
attach to shared memory in order to request a database connection",
- worker->bgw_name)));
+ worker->bgw_type)));
return false;
}
@@ -597,7 +601,7 @@ SanityCheckBackgroundWorker(BackgroundWorker *worker, int
elevel)
ereport(elevel,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("background worker \"%s\":
cannot request database access if starting at postmaster start",
- worker->bgw_name)));
+ worker->bgw_type)));
return false;
}
@@ -611,7 +615,7 @@ SanityCheckBackgroundWorker(BackgroundWorker *worker, int
elevel)
ereport(elevel,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("background worker \"%s\": invalid
restart interval",
- worker->bgw_name)));
+ worker->bgw_type)));
return false;
}
@@ -626,7 +630,7 @@ SanityCheckBackgroundWorker(BackgroundWorker *worker, int
elevel)
ereport(elevel,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("background worker \"%s\": parallel
workers may not be configured for restart",
- worker->bgw_name)));
+ worker->bgw_type)));
return false;
}
@@ -670,8 +674,8 @@ bgworker_die(SIGNAL_ARGS)
ereport(FATAL,
(errcode(ERRCODE_ADMIN_SHUTDOWN),
- errmsg("terminating background worker \"%s\" due to
administrator command",
- MyBgworkerEntry->bgw_name)));
+ errmsg("terminating %s due to administrator command",
+ MyBgworkerEntry->bgw_type)));
}
/*
@@ -710,7 +714,7 @@ StartBackgroundWorker(void)
IsBackgroundWorker = true;
/* Identify myself via ps */
- snprintf(buf, MAXPGPATH, "bgworker: %s", worker->bgw_name);
+ snprintf(buf, MAXPGPATH, "%s%s", worker->bgw_type,
worker->bgw_name_extra);
init_ps_display(buf, "", "", "");
/*
@@ -852,8 +856,8 @@ RegisterBackgroundWorker(BackgroundWorker *worker)
static int numworkers = 0;
if (!IsUnderPostmaster)
- ereport(DEBUG1,
- (errmsg("registering background worker \"%s\"",
worker->bgw_name)));
+ elog(DEBUG1,
+ "registering background worker \"%s%s\"",
worker->bgw_type, worker->bgw_name_extra);
if (!process_shared_preload_libraries_in_progress &&
strcmp(worker->bgw_library_name, "postgres") != 0)
@@ -862,7 +866,7 @@ RegisterBackgroundWorker(BackgroundWorker *worker)
ereport(LOG,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("background worker \"%s\": must
be registered in shared_preload_libraries",
- worker->bgw_name)));
+ worker->bgw_type)));
return;
}
@@ -874,7 +878,7 @@ RegisterBackgroundWorker(BackgroundWorker *worker)
ereport(LOG,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("background worker \"%s\": only dynamic
background workers can request notification",
- worker->bgw_name)));
+ worker->bgw_type)));
return;
}
diff --git a/src/backend/postmaster/postmaster.c
b/src/backend/postmaster/postmaster.c
index 35b4ec88d3..991caeace7 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -3070,7 +3070,6 @@ static bool
CleanupBackgroundWorker(int pid,
int exitstatus) /* child's exit
status */
{
- char namebuf[MAXPGPATH];
slist_mutable_iter iter;
slist_foreach_modify(iter, &BackgroundWorkerList)
@@ -3088,9 +3087,6 @@ CleanupBackgroundWorker(int pid,
exitstatus = 0;
#endif
- snprintf(namebuf, MAXPGPATH, "%s: %s", _("worker process"),
- rw->rw_worker.bgw_name);
-
if (!EXIT_STATUS_0(exitstatus))
{
/* Record timestamp, so we know when to restart the
worker. */
@@ -3112,7 +3108,7 @@ CleanupBackgroundWorker(int pid,
{
if (!EXIT_STATUS_0(exitstatus) &&
!EXIT_STATUS_1(exitstatus))
{
- HandleChildCrash(pid, exitstatus, namebuf);
+ HandleChildCrash(pid, exitstatus,
rw->rw_worker.bgw_type);
return true;
}
}
@@ -3125,7 +3121,7 @@ CleanupBackgroundWorker(int pid,
if (!ReleasePostmasterChildSlot(rw->rw_child_slot) &&
(rw->rw_worker.bgw_flags & BGWORKER_SHMEM_ACCESS) != 0)
{
- HandleChildCrash(pid, exitstatus, namebuf);
+ HandleChildCrash(pid, exitstatus,
rw->rw_worker.bgw_type);
return true;
}
@@ -3150,7 +3146,7 @@ CleanupBackgroundWorker(int pid,
ReportBackgroundWorkerExit(&iter); /* report child
death */
LogChildExit(EXIT_STATUS_0(exitstatus) ? DEBUG1 : LOG,
- namebuf, pid, exitstatus);
+ rw->rw_worker.bgw_type, pid,
exitstatus);
return true;
}
@@ -5576,9 +5572,9 @@ do_start_bgworker(RegisteredBgWorker *rw)
return false;
}
- ereport(DEBUG1,
- (errmsg("starting background worker process \"%s\"",
- rw->rw_worker.bgw_name)));
+ elog(DEBUG1,
+ "starting background worker process \"%s%s\"",
+ rw->rw_worker.bgw_type, rw->rw_worker.bgw_name_extra);
#ifdef EXEC_BACKEND
switch ((worker_pid = bgworker_forkexec(rw->rw_shmem_slot)))
diff --git a/src/backend/replication/logical/launcher.c
b/src/backend/replication/logical/launcher.c
index b956052014..624d8e9ca7 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -379,12 +379,13 @@ logicalrep_worker_launch(Oid dbid, Oid subid, const char
*subname, Oid userid,
bgw.bgw_start_time = BgWorkerStart_RecoveryFinished;
snprintf(bgw.bgw_library_name, BGW_MAXLEN, "postgres");
snprintf(bgw.bgw_function_name, BGW_MAXLEN, "ApplyWorkerMain");
+ snprintf(bgw.bgw_type, BGW_MAXLEN, "logical replication worker");
if (OidIsValid(relid))
- snprintf(bgw.bgw_name, BGW_MAXLEN,
- "logical replication worker for subscription
%u sync %u", subid, relid);
+ snprintf(bgw.bgw_name_extra, BGW_MAXLEN,
+ " for subscription %u sync %u", subid, relid);
else
- snprintf(bgw.bgw_name, BGW_MAXLEN,
- "logical replication worker for subscription
%u", subid);
+ snprintf(bgw.bgw_name_extra, BGW_MAXLEN,
+ " for subscription %u", subid);
bgw.bgw_restart_time = BGW_NEVER_RESTART;
bgw.bgw_notify_pid = MyProcPid;
@@ -706,7 +707,7 @@ ApplyLauncherRegister(void)
bgw.bgw_start_time = BgWorkerStart_RecoveryFinished;
snprintf(bgw.bgw_library_name, BGW_MAXLEN, "postgres");
snprintf(bgw.bgw_function_name, BGW_MAXLEN, "ApplyLauncherMain");
- snprintf(bgw.bgw_name, BGW_MAXLEN,
+ snprintf(bgw.bgw_type, BGW_MAXLEN,
"logical replication launcher");
bgw.bgw_restart_time = 5;
bgw.bgw_notify_pid = 0;
@@ -797,10 +798,6 @@ ApplyLauncherMain(Datum main_arg)
pqsignal(SIGTERM, logicalrep_worker_sigterm);
BackgroundWorkerUnblockSignals();
- /* Make it easy to identify our processes. */
- SetConfigOption("application_name", MyBgworkerEntry->bgw_name,
- PGC_USERSET, PGC_S_SESSION);
-
LogicalRepCtx->launcher_pid = MyProcPid;
/*
diff --git a/src/backend/replication/logical/worker.c
b/src/backend/replication/logical/worker.c
index c67720bd2f..e59b9db407 100644
--- a/src/backend/replication/logical/worker.c
+++ b/src/backend/replication/logical/worker.c
@@ -1467,10 +1467,6 @@ ApplyWorkerMain(Datum main_arg)
MyLogicalRepWorker->last_send_time = MyLogicalRepWorker->last_recv_time
=
MyLogicalRepWorker->reply_time = GetCurrentTimestamp();
- /* Make it easy to identify our processes. */
- SetConfigOption("application_name", MyBgworkerEntry->bgw_name,
- PGC_USERSET, PGC_S_SESSION);
-
/* Load the libpq-specific functions */
load_file("libpqwalreceiver", false);
diff --git a/src/backend/utils/adt/pgstatfuncs.c
b/src/backend/utils/adt/pgstatfuncs.c
index e0cae1ba1e..9d779491b5 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -21,6 +21,7 @@
#include "funcapi.h"
#include "miscadmin.h"
#include "pgstat.h"
+#include "postmaster/bgworker_internals.h"
#include "postmaster/postmaster.h"
#include "storage/proc.h"
#include "storage/procarray.h"
@@ -820,8 +821,32 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
}
}
/* Add backend type */
- values[17] =
-
CStringGetTextDatum(pgstat_get_backend_desc(beentry->st_backendType));
+ if (beentry->st_backendType == B_BG_WORKER)
+ {
+ slist_iter siter;
+ bool found = false;
+
+ slist_foreach(siter, &BackgroundWorkerList)
+ {
+ RegisteredBgWorker *rw;
+
+ rw =
slist_container(RegisteredBgWorker, rw_lnode, siter.cur);
+
+ if (rw->rw_pid == beentry->st_procpid)
+ {
+ values[17] =
+
CStringGetTextDatum(rw->rw_worker.bgw_type);
+ found = true;
+ break;
+ }
+ }
+
+ if (!found)
+ nulls[17] = true;
+ }
+ else
+ values[17] =
+
CStringGetTextDatum(pgstat_get_backend_desc(beentry->st_backendType));
}
else
{
diff --git a/src/include/postmaster/bgworker.h
b/src/include/postmaster/bgworker.h
index 51a5978ea8..daf7a3f7fe 100644
--- a/src/include/postmaster/bgworker.h
+++ b/src/include/postmaster/bgworker.h
@@ -87,7 +87,8 @@ typedef enum
typedef struct BackgroundWorker
{
- char bgw_name[BGW_MAXLEN];
+ char bgw_type[BGW_MAXLEN];
+ char bgw_name_extra[BGW_MAXLEN];
int bgw_flags;
BgWorkerStartTime bgw_start_time;
int bgw_restart_time; /* in seconds,
or BGW_NEVER_RESTART */
diff --git a/src/test/modules/test_shm_mq/setup.c
b/src/test/modules/test_shm_mq/setup.c
index 06c49bdb40..54c8dea4ed 100644
--- a/src/test/modules/test_shm_mq/setup.c
+++ b/src/test/modules/test_shm_mq/setup.c
@@ -219,7 +219,7 @@ setup_background_workers(int nworkers, dsm_segment *seg)
worker.bgw_restart_time = BGW_NEVER_RESTART;
sprintf(worker.bgw_library_name, "test_shm_mq");
sprintf(worker.bgw_function_name, "test_shm_mq_main");
- snprintf(worker.bgw_name, BGW_MAXLEN, "test_shm_mq");
+ snprintf(worker.bgw_type, BGW_MAXLEN, "test_shm_mq");
worker.bgw_main_arg = UInt32GetDatum(dsm_segment_handle(seg));
/* set bgw_notify_pid, so we can detect if the worker stops */
worker.bgw_notify_pid = MyProcPid;
diff --git a/src/test/modules/worker_spi/worker_spi.c
b/src/test/modules/worker_spi/worker_spi.c
index 9abfc714a9..9c217b69c8 100644
--- a/src/test/modules/worker_spi/worker_spi.c
+++ b/src/test/modules/worker_spi/worker_spi.c
@@ -181,8 +181,10 @@ worker_spi_main(Datum main_arg)
/* Connect to our database */
BackgroundWorkerInitializeConnection("postgres", NULL);
- elog(LOG, "%s initialized with %s.%s",
- MyBgworkerEntry->bgw_name, table->schema, table->name);
+ elog(LOG, "%s%s initialized with %s.%s",
+ MyBgworkerEntry->bgw_type,
+ MyBgworkerEntry->bgw_name_extra,
+ table->schema, table->name);
initialize_worker_spi(table);
/*
@@ -282,8 +284,9 @@ worker_spi_main(Datum main_arg)
SPI_tuptable->tupdesc,
1, &isnull));
if (!isnull)
- elog(LOG, "%s: count in %s.%s is now %d",
- MyBgworkerEntry->bgw_name,
+ elog(LOG, "%s%s: count in %s.%s is now %d",
+ MyBgworkerEntry->bgw_type,
+ MyBgworkerEntry->bgw_name_extra,
table->schema, table->name, val);
}
@@ -357,7 +360,8 @@ _PG_init(void)
*/
for (i = 1; i <= worker_spi_total_workers; i++)
{
- snprintf(worker.bgw_name, BGW_MAXLEN, "worker %d", i);
+ snprintf(worker.bgw_type, BGW_MAXLEN, "worker_spi worker");
+ snprintf(worker.bgw_name_extra, BGW_MAXLEN, " %d", i);
worker.bgw_main_arg = Int32GetDatum(i);
RegisterBackgroundWorker(&worker);
@@ -383,7 +387,8 @@ worker_spi_launch(PG_FUNCTION_ARGS)
worker.bgw_restart_time = BGW_NEVER_RESTART;
sprintf(worker.bgw_library_name, "worker_spi");
sprintf(worker.bgw_function_name, "worker_spi_main");
- snprintf(worker.bgw_name, BGW_MAXLEN, "worker %d", i);
+ snprintf(worker.bgw_type, BGW_MAXLEN, "worker_spi worker");
+ snprintf(worker.bgw_name_extra, BGW_MAXLEN, " %d", i);
worker.bgw_main_arg = Int32GetDatum(i);
/* set bgw_notify_pid so that we can use WaitForBackgroundWorkerStartup
*/
worker.bgw_notify_pid = MyProcPid;
--
2.13.0
--
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