postgres.git / summary / log / commit / refs
commit 5d2a47a2924240606ce1c57c98490fa41752ad41
Author: Michael Paquier <michael@paquier.xyz>
Date: Wed Oct 19 05:07:01 2022 +0000
First released in: 16.0, 15.1
Rework shutdown callback of archiver modules
As currently designed, with a callback registered in a ERROR_CLEANUP
block, the shutdown callback would get called twice when updating
archive_library on SIGHUP, which is something that we want to avoid to
ease the life of extension writers.
Anyway, an ERROR in the archiver process is treated as a FATAL, stopping
it immediately, hence there is no need for a ERROR_CLEANUP block.
Instead of that, the shutdown callback is not called upon
before_shmem_exit(), giving to the modules the opportunity to do any
cleanup actions before the server shuts down its subsystems.
While on it, this commit adds some testing coverage for the shutdown
callback. Neither shell_archive nor basic_archive have been using it,
and one is added to shell_archive, whose trigger is checked in a TAP
test through a shutdown sequence.
Author: Nathan Bossart, Bharath Rupireddy
Reviewed-by: Kyotaro Horiguchi, Michael Paquier
Discussion: https://postgr.es/m/20221015221328.GB1821022@nathanxps13
Backpatch-through: 15
doc/src/sgml/config.sgml | 5 +++--
src/backend/postmaster/pgarch.c | 27 ++++++++-------------------
src/backend/postmaster/shell_archive.c | 8 ++++++++
src/test/recovery/t/020_archive_status.pl | 14 ++++++++++++++
4 files changed, 33 insertions(+), 21 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 099867dd1b7..703f6d5a7f4 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -3618,8 +3618,9 @@ include_dir 'conf.d'
The library to use for archiving completed WAL file segments. If set to
an empty string (the default), archiving via shell is enabled, and
<xref linkend="guc-archive-command"/> is used. Otherwise, the specified
- shared library is used for archiving. For more information, see
- <xref linkend="backup-archiving-wal"/> and
+ shared library is used for archiving. The WAL archiver process is
+ restarted by the postmaster when this parameter changes. For more
+ information, see <xref linkend="backup-archiving-wal"/> and
<xref linkend="archive-modules"/>.
</para>
<para>
diff --git a/src/backend/postmaster/pgarch.c b/src/backend/postmaster/pgarch.c
index 1240f914237..327df4e9a5d 100644
--- a/src/backend/postmaster/pgarch.c
+++ b/src/backend/postmaster/pgarch.c
@@ -144,7 +144,7 @@ static void pgarch_die(int code, Datum arg);
static void HandlePgArchInterrupts(void);
static int ready_file_comparator(Datum a, Datum b, void *arg);
static void LoadArchiveLibrary(void);
-static void call_archive_module_shutdown_callback(int code, Datum arg);
+static void pgarch_call_module_shutdown_cb(int code, Datum arg);
/* Report shared memory space needed by PgArchShmemInit */
Size
@@ -252,13 +252,7 @@ PgArchiverMain(void)
/* Load the archive_library. */
LoadArchiveLibrary();
- PG_ENSURE_ERROR_CLEANUP(call_archive_module_shutdown_callback, 0);
- {
- pgarch_MainLoop();
- }
- PG_END_ENSURE_ERROR_CLEANUP(call_archive_module_shutdown_callback, 0);
-
- call_archive_module_shutdown_callback(0, 0);
+ pgarch_MainLoop();
proc_exit(0);
}
@@ -791,19 +785,14 @@ HandlePgArchInterrupts(void)
if (archiveLibChanged)
{
- /*
- * Call the currently loaded archive module's shutdown callback,
- * if one is defined.
- */
- call_archive_module_shutdown_callback(0, 0);
-
/*
* Ideally, we would simply unload the previous archive module and
* load the new one, but there is presently no mechanism for
* unloading a library (see the comment above
* internal_load_library()). To deal with this, we simply restart
* the archiver. The new archive module will be loaded when the
- * new archiver process starts up.
+ * new archiver process starts up. Note that this triggers the
+ * module's shutdown callback, if defined.
*/
ereport(LOG,
(errmsg("restarting archiver process because value of "
@@ -846,15 +835,15 @@ LoadArchiveLibrary(void)
if (ArchiveContext.archive_file_cb == NULL)
ereport(ERROR,
(errmsg("archive modules must register an archive callback")));
+
+ before_shmem_exit(pgarch_call_module_shutdown_cb, 0);
}
/*
- * call_archive_module_shutdown_callback
- *
- * Calls the loaded archive module's shutdown callback, if one is defined.
+ * Call the shutdown callback of the loaded archive module, if defined.
*/
static void
-call_archive_module_shutdown_callback(int code, Datum arg)
+pgarch_call_module_shutdown_cb(int code, Datum arg)
{
if (ArchiveContext.shutdown_cb != NULL)
ArchiveContext.shutdown_cb();
diff --git a/src/backend/postmaster/shell_archive.c b/src/backend/postmaster/shell_archive.c
index 19e240c2053..6306f5bd7bf 100644
--- a/src/backend/postmaster/shell_archive.c
+++ b/src/backend/postmaster/shell_archive.c
@@ -23,6 +23,7 @@
static bool shell_archive_configured(void);
static bool shell_archive_file(const char *file, const char *path);
+static void shell_archive_shutdown(void);
void
shell_archive_init(ArchiveModuleCallbacks *cb)
@@ -31,6 +32,7 @@ shell_archive_init(ArchiveModuleCallbacks *cb)
cb->check_configured_cb = shell_archive_configured;
cb->archive_file_cb = shell_archive_file;
+ cb->shutdown_cb = shell_archive_shutdown;
}
static bool
@@ -155,3 +157,9 @@ shell_archive_file(const char *file, const char *path)
elog(DEBUG1, "archived write-ahead log file \"%s\"", file);
return true;
}
+
+static void
+shell_archive_shutdown(void)
+{
+ elog(DEBUG1, "archiver process shutting down");
+}
diff --git a/src/test/recovery/t/020_archive_status.pl b/src/test/recovery/t/020_archive_status.pl
index 550fb37cb68..2108d50073a 100644
--- a/src/test/recovery/t/020_archive_status.pl
+++ b/src/test/recovery/t/020_archive_status.pl
@@ -234,4 +234,18 @@ ok( -f "$standby2_data/$segment_path_1_done"
".done files created after archive success with archive_mode=always on standby"
);
+# Check that the archiver process calls the shell archive module's shutdown
+# callback.
+$standby2->append_conf('postgresql.conf', "log_min_messages = debug1");
+$standby2->reload;
+
+# Run a query to make sure that the reload has taken effect.
+$standby2->safe_psql('postgres', q{SELECT 1});
+my $log_location = -s $standby2->logfile;
+
+$standby2->stop;
+my $logfile = slurp_file($standby2->logfile, $log_location);
+ok( $logfile =~ qr/archiver process shutting down/,
+ 'check shutdown callback of shell archive module');
+
done_testing();
[parent: 25fb9579bbb9]