I did a quick Purify run on the backend, and the first non-Irix leak
occured in the buffer manager...I won't be able to actually work on this
stuff for a while but there is definitely something going on in that area.
=+=------------------------/\---------------------------------=+=
Igor Natanzon |**| E-mail: igor@sba.miami.edu
=+=------------------------\/---------------------------------=+=
On Wed, 4 Jun 1997, Thomas G. Lockhart wrote:
> Here is an update on postgres backend buffer performance (and problems).
>
> I ran the regression tests with several sizes for the "-B" option for
> postmaster. The best performance was for the run with the largest value
> of -B. However, smaller values of -B seem to give results indicating a
> large memory leak or garbage collection problem in the backend.
>
> (results are for "time make runtest" under tcsh)
>
> TEST1:
> gemini$ /opt/postgres/current/bin/postmaster -B 128
> ...
> ACTUAL RESULTS OF REGRESSION TEST ARE NOW IN FILE regress.out
> 1.550u 4.580s 5:56.25 1.7% 0+0k 0+0io 16984pf+0w
>
> TEST2:
> gemini$ /opt/postgres/current/bin/postmaster
> ACTUAL RESULTS OF REGRESSION TEST ARE NOW IN FILE regress.out
> ...
> 1.250u 4.870s 6:45.65 1.5% 0+0k 0+0io 16863pf+0w
>
> TEST3:
> gemini$ /opt/postgres/current/bin/postmaster -B 16
> ...
> ACTUAL RESULTS OF REGRESSION TEST ARE NOW IN FILE regress.out
> 1.580u 4.690s 13:29.13 0.7% 0+0k 0+0io 16843pf+0w
>
> In all cases, if I repeat the regression test without restarting
> postmaster, the elapsed time becomes significantly higher. For runs with
> "-B 16", a second run of the regression test starts failing midway
> through with messages indicating that buffer space is exhausted.
>
> I am running on a RedHat Linux box with i686 processor(s).
>
> Vadim (and others?), can you see this feature in your regression runs? I
> am still sitting on Robert Withrow's Purify runs on the regression
> tests. Would those be helpful? Since the regression tests have changed
> so much since v6.0, and since many features tested in the new regression
> tests are not available in v6.0, I don't know if it would be useful to
> try running the new regression tests with the old release. I haven't
> tried distilling the problem down to a single test, because I don't
> really know what to look for or what is causing the symptoms.
>
> - Tom
>
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