Re: Avoid stuck of pbgench due to skipped transactions - Mailing list pgsql-hackers

On 2021/06/17 1:23, Yugo NAGATA wrote:
> I attached the v2 patch to clarify that I withdrew the v3 patch.

Thanks for the patch!

+                             * For very unrealistic rates under -T, some skipped
+                             * transactions are not counted because the catchup
+                             * loop is not fast enough just to do the scheduling
+                             * and counting at the expected speed.
+                             *
+                             * We do not bother with such a degenerate case.
+                             */

ISTM that the patch changes pgbench so that it can skip counting
some skipped transactions here even for realistic rates under -T.
Of course, which would happen very rarely. Is this understanding right?

On the other hand, even without the patch, in the first place, there seems
no guarantee that all the skipped transactions are counted under -T.
When the timer is exceeded in CSTATE_END_TX, a client ends without
checking outstanding skipped transactions. Therefore the "issue" that
some skipped transactions are not counted is not one the patch newly introdues.
So that behavior change by the patch would be acceptable.
Is this understanding right?

Regards,

-- 
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION