On 2021/03/11 13:42, Kyotaro Horiguchi wrote:
At Wed, 10 Mar 2021 19:21:00 -0800, Andres Freund <and...@anarazel.de> wrote in
Hi,
Two minor nits:
Thanks for the comments!
On 2021-03-10 21:47:51 +0900, Fujii Masao wrote:
+/* Shared memory area for archiver process */
+typedef struct PgArchData
+{
+ Latch *latch; /* latch to wake the archiver
up */
+ slock_t mutex; /* locks this struct */
+} PgArchData;
+
It doesn't really matter, but it'd be pretty trivial to avoid needing a
spinlock for this kind of thing. Just store the pgprocno of the archiver
in PgArchData.
Looks promising.
You mean that spinlock is not necessary by doing the followings?
- Save pgprocno of archiver in PgArchData, instead of latch and mutex.
- Set PgArch->pgprocno at the startup of archiver
- Reset PgArch->pgprocno to INVALID_PGPROCNO at pgarch_die()
- XLogArchiveNotify() sets the latch (i.e.,
&ProcGlobal->allProcs[PgArch->pgprocno].procLatch) if PgArch->pgprocno is not
INVALID_PGPROCNO
Right?
While getting rid of the spinlock doesn't seem like a huge win, it does
seem nicer that we'd automatically have a way to find data about the
archiver (e.g. pid).
PGPROC GetAuxProcessInfo(AuxProcType type)?
I don't think this new function is necessary.
ISTM that Andres said that it's worth adding pgprocno into PgArch because
which enables us to get the information about archiver more easily by
using that pgprocno. For example, we can get the pid of archiver by
&ProcGlobal->allProcs[PgArch->pgprocno].pid. That is, he thinks that
adding pgprocno has several merits. I agree that. Maybe I'm misunderstanding
his comment, though...
* checkpointer to exit as well, otherwise not. The archiver,
stats,
* and syslogger processes are disregarded since they are not
* connected to shared memory; we also disregard dead_end
children
* here. Walsenders are also disregarded, they will be
terminated
* later after writing the checkpoint record, like the archiver
* process.
*/
This comment in PostmasterStateMachine() is outdated now.
Right. Will fix a bit later.
Thanks!
Regards,
--
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION
