| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Fujii Masao <masao(dot)fujii(at)gmail(dot)com>, Andres Freund <andres(at)2ndquadrant(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: WalSndWakeup() and synchronous_commit=off |
| Date: | 2012-05-11 18:36:24 |
| Message-ID: | 10124.1336761384@sss.pgh.pa.us |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> That definitely doesn't seem ideal - a lot of things can pile up
> behind WALWriteLock. I'm not sure how big a problem it would be in
> practice, but we generally make a practice of avoiding sending signals
> while holding LWLocks whenever possible...
There's a good reason for that, which is that the scheduler might well
decide to go run the wakened process instead of you. Admittedly this
tends to not be a problem on machines with $bignum CPUs, but on
single-CPU machines I've seen it happen a lot.
Refactoring so that the signal is sent only after lock release seems
like a good idea to me.
regards, tom lane
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Andres Freund | 2012-05-11 18:40:40 | Re: WalSndWakeup() and synchronous_commit=off |
| Previous Message | Josh Berkus | 2012-05-11 18:21:35 | Agenda For 3rd Cluster Hackers Summit, May 15th in Ottawa |