Test results from buildfarm members mastodon/narwhal (Windows Server 2003)
make it look like that platform just plain loses FD_READ events
occasionally, and the only reason our previous coding seemed to work was
that it timed out every couple of seconds and retried the whole operation.
Try to verify this by reinserting a finite timeout into the pgstat loop.
This isn't meant to be a permanent patch either, just to confirm or
disprove a theory.
This should get rid of the usage of pgwin32_waitforsinglesocket entirely,
and perhaps thereby remove the race condition that's evidently still
present on some versions of Windows. The previous arrangement was a bit
unsafe anyway, since waiting at the recv() would not allow pgstat to notice
postmaster death.
When the "hot" members of PGPROC were split off to separate PGXACT structs,
many PGPROC fields referred to in comments were moved to PGXACT, but the
comments were neglected in the commit. Mostly this is just a search/replace
of PGPROC with PGXACT, but the way the dummy PGPROC entries are created for
prepared transactions changed more, making some of the comments totally
bogus.
Noah Misch
Log main-loop blocking events and the results of inquiry messages.
This is to get some clarity as to what's happening on those Windows
buildfarm members that still don't like the latch-ified stats collector.
This bulks up the postmaster log a tad, so I won't leave it in place for
long.
If the tablespace directory is missing entirely, we allow DROP TABLESPACE
to go through, on the grounds that it should be possible to clean up the
catalog entry in such a situation. However, we forgot that the pg_tblspc
symlink might still be there. We should try to remove the symlink too
(but not fail if it's no longer there), since not doing so can lead to
weird behavior subsequently, as per report from Michael Nolan.
There was some discussion of adding dependency links to prevent DROP
TABLESPACE when the catalogs still contain references to the tablespace.
That might be worth doing too, but it's an orthogonal question, and in
any case wouldn't be back-patchable.
Back-patch to 9.0, which is as far back as the logic looks like this.
We could possibly do something similar in 8.x, but given the lack of
reports I'm not sure it's worth the trouble, and anyway the case could
not arise in the form the logic is meant to cover (namely, a post-DROP
transaction rollback having resurrected the pg_tablespace entry after
some or all of the filesystem infrastructure is gone).
This reverts commit cb2f2873d6, restoring
the latch-ified stats collector logic. We'll soon see if this works any
better on the Windows buildfarm machines.
Make sure WaitLatchOrSocket regards FD_CLOSE as a read-ready condition.
We might want to tweak this further, but it was surely wrong as-is.
Make pgwin32_waitforsinglesocket detach its private event object from the
passed socket before returning. I suspect that failure to do so leads
to race conditions when other code (such as WaitLatchOrSocket) attaches
a different event object to the same socket. Moreover, the existing
coding meant that repeated calls to pgwin32_waitforsinglesocket would
perform ResetEvent on an event actively connected to a socket, which
is rumored to be an unsafe practice; the WSAEventSelect documentation
appears to recommend against this, though it does not say not to do it
in so many words.
Also, uniformly use the coding pattern "WSAEventSelect(s, NULL, 0)" to
detach events from sockets, rather than passing the event in the second
parameter. The WSAEventSelect documentation says that the second parameter
is ignored if the third is 0, so theoretically this should make no
difference. However, elsewhere on the same reference page the use of NULL
in this context is recommended, and I have found suggestions on the net
that some versions of Windows have bugs with a non-NULL second parameter
in this usage.
Some other mostly-cosmetic cleanup, such as using the right one of
WSAGetLastError and GetLastError for reporting errors from these functions.
rc should be an int here, not a pgsocket. Fairly harmless as long as
pgsocket is an integer type, but nonetheless wrong. Error introduced
in commit 87091cb1f1.
syslogger was coded to wake up once per second whether there was anything
useful to do or not. As part of our campaign to reduce the server's idle
power consumption, change it to use a latch for waiting. Now, in the
absence of any data to log or any signals to service, it will only wake up
at the programmed logfile rotation times (if any).
These were apparently never used. The AC_SUBST was probably just
added in a copy-and-paste manner. (The shell variables continue to be
used inside configure. The change is just that we don't need them
outside of configure.)
When using poll(), EOF on a socket is reported with the POLLHUP not
POLLIN flag (at least on Linux). WaitLatchOrSocket failed to check
this bit, causing it to go into a busy-wait loop if EOF occurs.
We earlier fixed the same mistake in the test for the state of the
postmaster_alive socket, but missed it for the caller-supplied socket.
Fortunately, this error is new in 9.2, since 9.1 only had a select()
based code path not a poll() based one.
Since we've got an "open items" list item about this, apparently some
people are pretty worried about it.
In passing remove a lot of trailing whitespace.
This example was quite old: it lacked the WAL writer and autovac launcher
as well as the more recently added checkpointer. Linux "ps" seems to show
slightly different stuff now too.
The string representation of ImportError changed. Remove printing
that; it's not necessary for the test.
The order in which members of a dict are printed changed. But this
was always implementation-dependent, so we have just been lucky for a
long time. Do the printing the hard way to ensure sorted order.
We previously recognized that citext wouldn't get marked as collatable
during pg_upgrade from a pre-9.1 installation, and hacked its
create-from-unpackaged script to manually perform the necessary catalog
adjustments. However, we overlooked the fact that domains over citext,
as well as the citext[] array type, need the same adjustments. Extend
the script to handle those cases.
Also, the documentation suggested that this was only an issue in pg_upgrade
scenarios, which is quite wrong; loading any dump containing citext from a
pre-9.1 server will also result in the type being wrongly marked.
I approached the documentation problem by changing the 9.1.2 release note
paragraphs about this issue, which is historically inaccurate. But it
seems better than having the information scattered in multiple places, and
leaving incorrect info in the 9.1.2 notes would be bad anyway. We'll still
need to mention the issue again in the 9.1.4 notes, but perhaps they can
just reference 9.1.2 for fix instructions.
Per report from Evan Carroll. Back-patch into 9.1.
When inserting the downlinks for a split gist page, we used hold the locks
on the child pages until the insertion into the parent - and recursively its
parent if it had to be split too - were all completed. Change that so that
the locks on child pages are released after the insertion in the immediate
parent is done, before recursing further up the tree.
This reduces the number of lwlocks that are held simultaneously. Holding
many locks is bad for concurrency, and in extreme cases you can even hit
the limit of 100 simultaneously held lwlocks in a backend. If you're really
unlucky, you can hit the limit while in a critical section, which brings
down the whole system.
This fixes bug #6629 reported by Tom Forbes. Backpatch to 9.1. The page
splitting code was rewritten in 9.1, and the old code did not have this
problem.
Rewrite description of "include_if_exists" for clarity. Add subsection
headings to make the structure of the page a little clearer. A couple
other minor improvements too.
Josh Kupershmidt and Tom Lane
HEAD documentation was failing to build as US PDF for me, because a link
to "CREATE CAST" was getting split across pages. Adjust wording to
remove this rather gratuitous cross-reference.
This patch reverts commit 49340037ee and some
follow-on tweaking in pgstat.c. While the basic scheme of latch-ifying the
stats collector seems sound enough, it's failing on most Windows buildfarm
members for unknown reasons, and there's no time left to debug that before
9.2beta1. Better to ship a beta version without this improvement. I hope
to re-revert this once beta1 is out, though.
Per a suggestion from Peter Geoghegan, make WaitLatch responsible for
verifying that the WL_POSTMASTER_DEATH bit it returns is truthful (by
testing PostmasterIsAlive). Then simplify its callers, who no longer
need to do that for themselves. Remove weasel wording about falsely-set
result bits from WaitLatch's API contract.
The old way of implementing slicing support by implementing
PySequenceMethods.sq_slice no longer works in Python 3. You now have
to implement PyMappingMethods.mp_subscript. Do this by simply
proxying the call to the wrapped list of result dictionaries.
Consolidate some of the subscripting regression tests.
Jan Urbański
The original coding failed to reset ImmediateInterruptOK before returning,
which would potentially allow a subsequent query-cancel interrupt to be
accepted at an unsafe point. This is a really nasty bug since it's so hard
to predict the consequences, but they could be unpleasant.
Also, ensure that signal handlers are serviced before this function
returns, even if the semaphore is already set. This should make the
behavior more like Unix.
Back-patch to all supported versions.
Ensure that signal handlers are serviced before this function returns.
This should make the behavior more like Unix. Also, add some more
error checking, and make some other cosmetic improvements.
No back-patch since it's not clear whether this is fixing any live bug
that would affect 9.1. I'm more concerned about 9.2 anyway given our
considerable recent expansions in the usage of WaitLatch.
It was already on its last legs, and it turns out that it was
accidentally broken in commit 89e850e6fd
and no one cared. So remove the rest the support for it and update
the documentation to indicate that Python 2.3 is now required.
Tom Lane
Heikki Linnakangas
Peter Eisentraut
Bruce Momjian
Simon Riggs
Robert Haas