Hello
We have lists of backend types scattered through the tree. I found two
current ones, and Euler Taveira wants to add a couple more[1]. His
patch is actually blocked on not adding more, so this seems worth doing.
Bikeshedding welcome (for a limited time).
[1] https://postgr.es/m/313aa202-b5fa-4e3f-95d0-83425575c...@app.fastmail.com
A couple points. First, launch_backend.c has its own strings for
process names, inconsistent with the ones in miscinit.c. I think we
should ignore the ones in launch_backend.c, because they're less
polished and not used for anything interesting, whereas the ones in
miscinit.c::GetBackendTypeDesc() are -- particularly init_ps_display and
pg_stat_activity.
Second, in discussion [2] leading to commit 18d67a8d7d30 (Nov 2024) it
was agreed to add support for translating backend type descriptions.
I'm not really sure that this is useful. It would be, if set_ps_display
and pg_stat_activity used translated names, so that you could match what
log messages say with what the process lists show. But I think we've
historically not translated those. We have a few translatable strings
as the argument of HandleChildCrash() in postmaster.c, but those are
using names that are yet a third source of strings; I'm not a fan of
this. (For staters, if a translation decided to use non-ascii chars for
process names, would that work okay in set_ps_display? I bet it
wouldn't, because that's using strlen()). So I would propose to rewind
a bit here, and remove translation from all those places so that the
output is consistent (== usable) between log messages and ps/pg_stat_activity.
[2]
https://www.postgresql.org/message-id/flat/a102f15f-eac4-4ff2-af02-f9ff209ec66f%40iki.fi
Third, I didn't do it here, but HandleChildCrash is currently called
like
HandleChildCrash(pid, exitstatus,
_("WAL writer process"));
creating yet another source of strings to describe process types.
I think it would be much better to avoid that by using
HandleChildCrash(pid, exitstatus,
_(GetBackendTypeDesc(B_WAL_WRITER));
instead. If we decide to get rid of the translation, then
HandleChildCrash(pid, exitstatus,
GetBackendTypeDesc(B_WAL_WRITER);
This last one would be my preference actually. Note that we use this
string in an error that looks like this (LogChildExit):
/*------
translator: %s is a noun phrase describing a child process, such as
"server process" */
(errmsg("%s (PID %d) exited with exit code %d",
procname, pid, WEXITSTATUS(exitstatus)),
I would change this to
errmsg("process %d of type \"%s\" exited with exit code %d",
pid, procname, WEXITSTATUS())
Note that in the original, the process name is translated, and in my
proposal it wouldn't be. (This helps match the log message with "ps"
and pg_stat_activity).
Fourth: patch 0002 is a necessary hack to get the proctype_list.h
strings be picked up for translation by gettext in makefiles. It's
quite ugly! I'd rather not have it at all. I have no idea how to do
this in Meson.
--
Álvaro Herrera Breisgau, Deutschland — https://www.EnterpriseDB.com/
"I dream about dreams about dreams", sang the nightingale
under the pale moon (Sandman)
>From 1165efd15dbc73093eb16fffc05047a8455ecb5d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=81lvaro=20Herrera?= <alvhe...@kurilemu.de>
Date: Tue, 15 Jul 2025 18:19:27 +0200
Subject: [PATCH 1/2] Create a separate file listing backend types
Use our established coding pattern to reduce maintenance pain when
adding other per-process-type characteristics.
Like PG_KEYWORD, PG_CMDTAG, PG_RMGR.
---
src/backend/postmaster/launch_backend.c | 32 ++------------
src/backend/utils/init/miscinit.c | 59 ++-----------------------
src/include/postmaster/proctype_list.h | 44 ++++++++++++++++++
3 files changed, 52 insertions(+), 83 deletions(-)
create mode 100644 src/include/postmaster/proctype_list.h
diff --git a/src/backend/postmaster/launch_backend.c b/src/backend/postmaster/launch_backend.c
index bf6b55ee830..d8ac514bbbc 100644
--- a/src/backend/postmaster/launch_backend.c
+++ b/src/backend/postmaster/launch_backend.c
@@ -177,34 +177,10 @@ typedef struct
} child_process_kind;
static child_process_kind child_process_kinds[] = {
- [B_INVALID] = {"invalid", NULL, false},
-
- [B_BACKEND] = {"backend", BackendMain, true},
- [B_DEAD_END_BACKEND] = {"dead-end backend", BackendMain, true},
- [B_AUTOVAC_LAUNCHER] = {"autovacuum launcher", AutoVacLauncherMain, true},
- [B_AUTOVAC_WORKER] = {"autovacuum worker", AutoVacWorkerMain, true},
- [B_BG_WORKER] = {"bgworker", BackgroundWorkerMain, true},
-
- /*
- * WAL senders start their life as regular backend processes, and change
- * their type after authenticating the client for replication. We list it
- * here for PostmasterChildName() but cannot launch them directly.
- */
- [B_WAL_SENDER] = {"wal sender", NULL, true},
- [B_SLOTSYNC_WORKER] = {"slot sync worker", ReplSlotSyncWorkerMain, true},
-
- [B_STANDALONE_BACKEND] = {"standalone backend", NULL, false},
-
- [B_ARCHIVER] = {"archiver", PgArchiverMain, true},
- [B_BG_WRITER] = {"bgwriter", BackgroundWriterMain, true},
- [B_CHECKPOINTER] = {"checkpointer", CheckpointerMain, true},
- [B_IO_WORKER] = {"io_worker", IoWorkerMain, true},
- [B_STARTUP] = {"startup", StartupProcessMain, true},
- [B_WAL_RECEIVER] = {"wal_receiver", WalReceiverMain, true},
- [B_WAL_SUMMARIZER] = {"wal_summarizer", WalSummarizerMain, true},
- [B_WAL_WRITER] = {"wal_writer", WalWriterMain, true},
-
- [B_LOGGER] = {"syslogger", SysLoggerMain, false},
+#define PG_PROCTYPE(bktype, description, main_func, shmem_attach) \
+ [bktype] = {description, main_func, shmem_attach},
+#include "postmaster/proctype_list.h"
+#undef PG_PROCTYPE
};
const char *
diff --git a/src/backend/utils/init/miscinit.c b/src/backend/utils/init/miscinit.c
index 43b4dbccc3d..53a232cee41 100644
--- a/src/backend/utils/init/miscinit.c
+++ b/src/backend/utils/init/miscinit.c
@@ -266,62 +266,11 @@ GetBackendTypeDesc(BackendType backendType)
switch (backendType)
{
- case B_INVALID:
- backendDesc = gettext_noop("not initialized");
- break;
- case B_ARCHIVER:
- backendDesc = gettext_noop("archiver");
- break;
- case B_AUTOVAC_LAUNCHER:
- backendDesc = gettext_noop("autovacuum launcher");
- break;
- case B_AUTOVAC_WORKER:
- backendDesc = gettext_noop("autovacuum worker");
- break;
- case B_BACKEND:
- backendDesc = gettext_noop("client backend");
- break;
- case B_DEAD_END_BACKEND:
- backendDesc = gettext_noop("dead-end client backend");
- break;
- case B_BG_WORKER:
- backendDesc = gettext_noop("background worker");
- break;
- case B_BG_WRITER:
- backendDesc = gettext_noop("background writer");
- break;
- case B_CHECKPOINTER:
- backendDesc = gettext_noop("checkpointer");
- break;
- case B_IO_WORKER:
- backendDesc = gettext_noop("io worker");
- break;
- case B_LOGGER:
- backendDesc = gettext_noop("logger");
- break;
- case B_SLOTSYNC_WORKER:
- backendDesc = gettext_noop("slotsync worker");
- break;
- case B_STANDALONE_BACKEND:
- backendDesc = gettext_noop("standalone backend");
- break;
- case B_STARTUP:
- backendDesc = gettext_noop("startup");
- break;
- case B_WAL_RECEIVER:
- backendDesc = gettext_noop("walreceiver");
- break;
- case B_WAL_SENDER:
- backendDesc = gettext_noop("walsender");
- break;
- case B_WAL_SUMMARIZER:
- backendDesc = gettext_noop("walsummarizer");
- break;
- case B_WAL_WRITER:
- backendDesc = gettext_noop("walwriter");
- break;
+#define PG_PROCTYPE(bktype, description, main_func, shmem_attach) \
+ case bktype: backendDesc = gettext_noop(description); break;
+#include "postmaster/proctype_list.h"
+#undef PG_PROCTYPE
}
-
return backendDesc;
}
diff --git a/src/include/postmaster/proctype_list.h b/src/include/postmaster/proctype_list.h
new file mode 100644
index 00000000000..749a6db8364
--- /dev/null
+++ b/src/include/postmaster/proctype_list.h
@@ -0,0 +1,44 @@
+/*-------------------------------------------------------------------------
+ *
+ * proctype_list.h
+ *
+ * The list of process types is kept on its own source file for use by
+ * automatic tools. The exact representation of a process type is
+ * determined by the PG_PROCTYPE macro, which is not defined in this
+ * file; it can be defined by the caller for special purposes.
+ *
+ * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * IDENTIFICATION
+ * src/include/postmaster/proctype_list.h
+ *
+ *-------------------------------------------------------------------------
+ */
+
+/* there is deliberately not an #ifndef PROCTYPE_LIST_H here */
+
+/*
+ * List of process types (symbol, description, Main function, shmem_attach)
+ * entries.
+ */
+
+/* bktype, description, main_func, shmem_attach */
+PG_PROCTYPE(B_ARCHIVER, "archiver", PgArchiverMain, true)
+PG_PROCTYPE(B_AUTOVAC_LAUNCHER, "autovacuum launcher", AutoVacLauncherMain, true)
+PG_PROCTYPE(B_AUTOVAC_WORKER, "autovacuum worker", AutoVacWorkerMain, true)
+PG_PROCTYPE(B_BACKEND, "client backend", BackendMain, true)
+PG_PROCTYPE(B_BG_WORKER, "background worker", BackgroundWorkerMain, true)
+PG_PROCTYPE(B_BG_WRITER, "background writer", BackgroundWriterMain, true)
+PG_PROCTYPE(B_CHECKPOINTER, "checkpointer", CheckpointerMain, true)
+PG_PROCTYPE(B_DEAD_END_BACKEND, "dead-end client backend", BackendMain, true)
+PG_PROCTYPE(B_INVALID, "invalid", NULL, false)
+PG_PROCTYPE(B_IO_WORKER, "io worker", IoWorkerMain, true)
+PG_PROCTYPE(B_LOGGER, "syslogger", SysLoggerMain, false)
+PG_PROCTYPE(B_SLOTSYNC_WORKER, "slotsync worker", ReplSlotSyncWorkerMain, true)
+PG_PROCTYPE(B_STANDALONE_BACKEND, "standalone backend", NULL, false)
+PG_PROCTYPE(B_STARTUP, "startup", StartupProcessMain, true)
+PG_PROCTYPE(B_WAL_RECEIVER, "walreceiver", WalReceiverMain, true)
+PG_PROCTYPE(B_WAL_SENDER, "walsender", NULL, true)
+PG_PROCTYPE(B_WAL_SUMMARIZER, "walsummarizer", WalSummarizerMain, true)
+PG_PROCTYPE(B_WAL_WRITER, "walwriter", WalWriterMain, true)
--
2.39.5
>From f60cd8acee00e954a28e0fb9d3a6fe0ab9221ce2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=81lvaro=20Herrera?= <alvhe...@kurilemu.de>
Date: Tue, 15 Jul 2025 19:14:00 +0200
Subject: [PATCH 2/2] Translation support for process type descriptions.
But do we really want this?
---
src/backend/nls.mk | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/src/backend/nls.mk b/src/backend/nls.mk
index b7d5dd46e45..d75aa8bc5ef 100644
--- a/src/backend/nls.mk
+++ b/src/backend/nls.mk
@@ -16,7 +16,8 @@ GETTEXT_TRIGGERS = $(BACKEND_COMMON_GETTEXT_TRIGGERS) \
ereport_startup_progress \
json_token_error:2 \
json_manifest_parse_failure:2 \
- error_cb:2
+ error_cb:2 \
+ PG_PROCTYPE:2
GETTEXT_FLAGS = $(BACKEND_COMMON_GETTEXT_FLAGS) \
GUC_check_errmsg:1:c-format \
GUC_check_errdetail:1:c-format \
@@ -28,7 +29,7 @@ GETTEXT_FLAGS = $(BACKEND_COMMON_GETTEXT_FLAGS) \
error_cb:2:c-format
gettext-files: generated-parser-sources generated-headers
- find $(srcdir) $(srcdir)/../common $(srcdir)/../port -name '*.c' -print | LC_ALL=C sort >$@
+ (find $(srcdir) $(srcdir)/../common $(srcdir)/../port -name '*.c' -print ; echo $(srcdir)/"../include/postmaster/backend_types.h" ) | LC_ALL=C sort >$@
my-clean:
rm -f gettext-files
--
2.39.5
