Dear Tom,
Besides a no optimization compilation of 7.4.3, what else
would you recommend to explore this problem further? Thanks. --Bob
Tom Lane writes:
>
>
> "Robert E. Bruccoleri" <bruc@stone.congenomics.com> writes:
> > Question: were there any significant changes made to the
> > buffer management code between 7.4 and 8.0 that would explain the
> > difference?
>
> There are some nontrivial changes, but none that I would regard as
> likely to cause a multiprocessing error to magically go away. More
> to the point, if there is such a bug in 7.4.3 there's no guarantee
> it won't come back again.
>
> > I haven't tried rerunning 7.4.3 without optimization to see if
> > the problem disappears in that release. Since the 8.0beta1 release
> > appears OK, and the test run takes about three days, so I'm reluctant
> > to do it unless there's some value in performing test. Please tell me
> > if there is.
>
> If you believe this is not a hardware problem, you'd better keep
> digging. There is no known reason for 7.4 to fail like that.
> It would be folly to assume that we've fixed the problem without
> knowing it.
>
> > Another question: on a machine which has this high level of
> > parallelism, does it make sense to use a spinlock to control access to
> > the buffer cache instead of a lightweight lock?
>
> No. The angst you've probably been reading is focused around the
> spinlock part of the LWLock --- simplifying the LWLock to a bare
> spinlock will not improve matters.
>
> regards, tom lane
>
+-----------------------------+------------------------------------+
| Robert E. Bruccoleri, Ph.D. | email: bruc@acm.org |
| President, Congenair LLC | URL: http://www.congen.com/~bruc |
| P.O. Box 314 | Phone: 609 818 7251 |
| Pennington, NJ 08534 | |
+-----------------------------+------------------------------------+
