See also:
https://commitfest.postgresql.org/27/2390/
https://www.postgresql.org/message-id/flat/caobau_yy5bt0vtpz2_lum6cucgeqmynoj8-rgto+c2+w3de...@mail.gmail.com
b025f32e0b Add leader_pid to pg_stat_activity
--
Justin
>From 5268e89fb32fbb639cb39796729dfe0dfcf14705 Mon Sep 17 00:00:00 2001
From: Justin Pryzby <pryz...@telsasoft.com>
Date: Fri, 13 Mar 2020 22:03:06 -0500
Subject: [PATCH v2] Include the leader PID in logfile
See also: b025f32e0b, which adds the leader PID to pg_stat_activity
---
doc/src/sgml/config.sgml | 11 +++++++++-
src/backend/utils/error/elog.c | 20 +++++++++++++++++++
src/backend/utils/misc/postgresql.conf.sample | 1 +
3 files changed, 31 insertions(+), 1 deletion(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 3cac340f32..f6ded2bc45 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -6491,6 +6491,14 @@ local0.* /var/log/postgresql
<entry>Process ID</entry>
<entry>no</entry>
</row>
+ <row>
+ <entry><literal>%k</literal></entry>
+ <entry>Process ID of the parallel group leader if this
+ process is or was involved in parallel query, null
+ otherwise. For a parallel group leader, this field is
+ set to its own process ID.</entry>
+ <entry>no</entry>
+ </row>
<row>
<entry><literal>%t</literal></entry>
<entry>Time stamp without milliseconds</entry>
@@ -6789,7 +6797,7 @@ log_line_prefix = '%m [%p] %q%u@%d/%a '
character count of the error position therein,
location of the error in the PostgreSQL source code
(if <varname>log_error_verbosity</varname> is set to <literal>verbose</literal>),
- application name, and backend type.
+ application name, backend type, and leader PID.
Here is a sample table definition for storing CSV-format log output:
<programlisting>
@@ -6819,6 +6827,7 @@ CREATE TABLE postgres_log
location text,
application_name text,
backend_type text,
+ leader_pid integer,
PRIMARY KEY (session_id, session_line_num)
);
</programlisting>
diff --git a/src/backend/utils/error/elog.c b/src/backend/utils/error/elog.c
index 62eef7b71f..0f5881355d 100644
--- a/src/backend/utils/error/elog.c
+++ b/src/backend/utils/error/elog.c
@@ -77,6 +77,7 @@
#include "postmaster/syslogger.h"
#include "storage/ipc.h"
#include "storage/proc.h"
+#include "storage/procarray.h"
#include "tcop/tcopprot.h"
#include "utils/guc.h"
#include "utils/memutils.h"
@@ -2560,6 +2561,18 @@ log_line_prefix(StringInfo buf, ErrorData *edata)
else
appendStringInfo(buf, "%d", MyProcPid);
break;
+
+ case 'k':
+ if (MyBackendType != B_BG_WORKER)
+ ; /* Do nothing */
+ else if (!MyProc->lockGroupLeader)
+ ; /* Do nothing */
+ else if (padding != 0)
+ appendStringInfo(buf, "%*d", padding, MyProc->lockGroupLeader->pid);
+ else
+ appendStringInfo(buf, "%d", MyProc->lockGroupLeader->pid);
+ break;
+
case 'l':
if (padding != 0)
appendStringInfo(buf, "%*ld", padding, log_line_number);
@@ -2948,6 +2961,13 @@ write_csvlog(ErrorData *edata)
else
appendCSVLiteral(&buf, GetBackendTypeDesc(MyBackendType));
+ appendStringInfoChar(&buf, ',');
+
+ /* leader PID */
+ if (MyBackendType == B_BG_WORKER &&
+ MyProc->lockGroupLeader)
+ appendStringInfo(&buf, "%d", MyProc->lockGroupLeader->pid);
+
appendStringInfoChar(&buf, '\n');
/* If in the syslogger process, try to write messages direct to file */
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index aa44f0c9bf..6874792a15 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -530,6 +530,7 @@
# %h = remote host
# %b = backend type
# %p = process ID
+ # %k = leader PID
# %t = timestamp without milliseconds
# %m = timestamp with milliseconds
# %n = timestamp with milliseconds (as a Unix epoch)
--
2.17.0
