On 11/15/2010 03:24 PM, Alvaro Herrera wrote:
Excerpts from Tom Lane's message of sáb nov 13 19:07:50 -0300 2010:
Stefan Kaltenbrunner<ste...@kaltenbrunner.cc> writes:
On 11/13/2010 06:58 PM, Tom Lane wrote:
Just looking at it, I think that the logic in canAcceptConnections got
broken by somebody in 8.4, and then broken some more in 9.0: in some
cases it will return an "okay to proceed" status without having checked
for TOOMANY children. Was this system possibly in PM_WAIT_BACKUP or
PM_HOT_STANDBY state? What version was actually running?
I don't have too many details on the actual setup (working on that) but
the box in question is running 8.4.2 and had no issues before the
upgrade to 8.4 (ie 8.3 was reported to work fine - so a 8.4+ breakage
looks plausible).
Well, this failure would certainly involve a flood of connection
attempts, so it's possible it's a pre-existing bug that they just did
not happen to trip over before. But the sequence of events that I'm
thinking about is a smart shutdown attempt (SIGTERM to postmaster)
while an online backup is in progress, followed by a flood of
near-simultaneous connection attempts while the backup is still active.
As far as I could gather from Stefan's description, I think this is
pretty unlikely. It seems to me that the "too many children" error
message is very common in the 8.3 setup already, and the only reason
they have a problem on 8.4 is that it crashes instead.
not sure if that is true - but 8.4 crashes whereas 8.3 just (seems to)
works - the issue is still there with 8_4_STABLE...
DEBUG3 level output (last few hours - 7MB in size) is available under
http://www.kaltenbrunner.cc/files/postgresql-2010-11-24_143513.log
From looking at the code I'm not immediatly seeing what is going wrong
here but maybe somebody else has an idea.
Stefan
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