Now that we know the cause of the Win32 failure (FRONTEND), we don't
need the Win32 part of this patch anymore right? (The stats display
part was already applied.)
---------------------------------------------------------------------------
Peter Brant wrote:
> Hi all,
>
> Attached are two patches which in combination make pg_stat_activity
> work reliably for us on Windows.
>
> The mysterious socket error turned out to be WSAEWOULDBLOCK. Per
> http://msdn.microsoft.com/library/default.asp?url=/library/en-us/winsock/winsock/windows_sockets_error_codes_2.asp
> , it seems the thing to do is loop and try again. pipe.patch does
> that.
>
> pgstat.patch removes the delayed destroy code for backends, databases,
> and tables. Database and table entries are cleaned up immediately upon
> receipt of the appropriate message.
>
> Both patches were necessary to make pg_stat_activity work reliably.
> With no changes, with a connection pool size of 31, under load, we'd
> typically see < 5 rows in pg_stat_activity. With pgstat.patch applied,
> the number of rows would typically be between 15 and 20. With
> pipe.patch also applied, the number of rows in pg_stat_activity was
> accurate.
>
> The test server withstood an approximately four hour test stress test
> which replays captured Web traffic, but at full blast. The machine was
> completely swamped, but there were no socket errors over the test run
> (compared to a frequency of once every couple minutes before).
>
> The one remaining problem is that there seems to be a race condition
> when installing the temporary stats file on Windows. As we were
> monitoring pg_stat_activity during the test run, occasionally we'd get a
> response with zero rows. This may not be much of a problem during
> normal conditions (the server was completely overloaded and we were
> banging away with "Up Arrow", "Enter" watching pg_stat_activity).
>
> What's the best way to do an atomic rename on Windows? Alternatively,
> would it make sense to sleep and try again (up to some limit) when
> trying to open the stats file on Windows?
>
> Pete
>
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>
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--
Bruce Momjian http://candle.pha.pa.us
EnterpriseDB http://www.enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +
