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MDEV-26811: Assertion "log_sys->n_pending_flushes == 1" fails

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In commit 1cb218c37cc3fe01a1ff2fe9b1cbfb591e90d5ce (MDEV-26450)
we introduced the function log_write_and_flush(), which may
compete with log_checkpoint() invoking log_write_flush_to_disk_low()
from another thread.

The assertion n_pending_flushes==1 is too strict.
There is no possibility of a race condition here, because
fil_flush() is protected by fil_system->mutex and the
rest will be protected by log_sys->mutex.

log_write_flush_to_disk_low(), log_write_and_flush():
Relax the assertions to test for a nonzero count.
This commit is contained in:
Marko Mäkelä 2021-10-13 10:38:41 +03:00
parent 6f32b28be5
commit 2bb8d7c2f3
1 changed files with 3 additions and 8 deletions
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11
storage/innobase/log/log0log.cc
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@ -983,13 +983,9 @@ loop:
/** Flush the recently written changes to the log file.
and invoke log_mutex_enter(). */
static
void
log_write_flush_to_disk_low()
static void log_write_flush_to_disk_low()
{
/* FIXME: This is not holding log_sys->mutex while
calling os_event_set()! */
ut_a(log_sys->n_pending_flushes == 1); /* No other threads here */
ut_a(log_sys->n_pending_flushes);
bool do_flush = srv_file_flush_method != SRV_O_DSYNC;
@ -997,7 +993,6 @@ log_write_flush_to_disk_low()
fil_flush(SRV_LOG_SPACE_FIRST_ID);
}
log_mutex_enter();
if (do_flush) {
log_sys->flushed_to_disk_lsn = log_sys->current_flush_lsn;
@ -1329,7 +1324,7 @@ ATTRIBUTE_COLD void log_write_and_flush()
/* Code adapted from log_write_flush_to_disk_low() */
ut_a(log_sys->n_pending_flushes == 1); /* No other threads here */
ut_a(log_sys->n_pending_flushes);
if (srv_file_flush_method != SRV_O_DSYNC)
fil_flush(SRV_LOG_SPACE_FIRST_ID);