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aio: Improve debug logging around waiting for IOs

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Trying to investigate a bug report by Alexander Lakhin made it apparent that
the debug logging around waiting for IO completion is insufficient. Fix that.

Discussion: https://postgr.es/m/h4in2db37vepagmi2oz5vvqymjasc5gyb4lpqkunj4eusu274i@37jpd3c2spd3
This commit is contained in:
Andres Freund 2025-04-25 12:31:42 -04:00
parent 500b61769f
commit 039bfc457e
1 changed files with 25 additions and 4 deletions
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29
src/backend/storage/aio/aio.c
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@ -711,8 +711,10 @@ pgaio_io_wait_for_free(void)
{ {
int reclaimed = 0; int reclaimed = 0;
pgaio_debug(DEBUG2, "waiting for self with %d pending", pgaio_debug(DEBUG2, "waiting for free IO with %d pending, %d in-flight, %d idle IOs",
pgaio_my_backend->num_staged_ios); pgaio_my_backend->num_staged_ios,
dclist_count(&pgaio_my_backend->in_flight_ios),
dclist_is_empty(&pgaio_my_backend->idle_ios));
/* /*
* First check if any of our IOs actually have completed - when using * First check if any of our IOs actually have completed - when using
@ -743,7 +745,12 @@ pgaio_io_wait_for_free(void)
pgaio_submit_staged(); pgaio_submit_staged();
if (dclist_count(&pgaio_my_backend->in_flight_ios) == 0) if (dclist_count(&pgaio_my_backend->in_flight_ios) == 0)
elog(ERROR, "no free IOs despite no in-flight IOs"); ereport(ERROR,
errmsg_internal("no free IOs despite no in-flight IOs"),
errdetail_internal("%d pending, %d in-flight, %d idle IOs",
pgaio_my_backend->num_staged_ios,
dclist_count(&pgaio_my_backend->in_flight_ios),
dclist_is_empty(&pgaio_my_backend->idle_ios)));
/* /*
* Wait for the oldest in-flight IO to complete. * Wait for the oldest in-flight IO to complete.
@ -1136,7 +1143,13 @@ pgaio_closing_fd(int fd)
* For now just submit all staged IOs - we could be more selective, but * For now just submit all staged IOs - we could be more selective, but
* it's probably not worth it. * it's probably not worth it.
*/ */
pgaio_submit_staged(); if (pgaio_my_backend->num_staged_ios > 0)
{
pgaio_debug(DEBUG2,
"submitting %d IOs before FD %d gets closed",
pgaio_my_backend->num_staged_ios, fd);
pgaio_submit_staged();
}
/* /*
* If requested by the IO method, wait for all IOs that use the * If requested by the IO method, wait for all IOs that use the
@ -1168,6 +1181,10 @@ pgaio_closing_fd(int fd)
if (!ioh) if (!ioh)
break; break;
pgaio_debug_io(DEBUG2, ioh,
"waiting for IO before FD %d gets closed, %d in-flight IOs",
fd, dclist_count(&pgaio_my_backend->in_flight_ios));
/* see comment in pgaio_io_wait_for_free() about raciness */ /* see comment in pgaio_io_wait_for_free() about raciness */
pgaio_io_wait(ioh, ioh->generation); pgaio_io_wait(ioh, ioh->generation);
} }
@ -1199,6 +1216,10 @@ pgaio_shutdown(int code, Datum arg)
{ {
PgAioHandle *ioh = dclist_head_element(PgAioHandle, node, &pgaio_my_backend->in_flight_ios); PgAioHandle *ioh = dclist_head_element(PgAioHandle, node, &pgaio_my_backend->in_flight_ios);
pgaio_debug_io(DEBUG2, ioh,
"waiting for IO to complete during shutdown, %d in-flight IOs",
dclist_count(&pgaio_my_backend->in_flight_ios));
/* see comment in pgaio_io_wait_for_free() about raciness */ /* see comment in pgaio_io_wait_for_free() about raciness */
pgaio_io_wait(ioh, ioh->generation); pgaio_io_wait(ioh, ioh->generation);
} }