Tom Lane wrote:
I was looking at this recent nonrepeatable buildfarm failure:
http://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=polecat&dt=2010-03-11%2021:45:10
which has several instances of the known "pgstat wait timeout" problem
during the parallel regression tests.
I was disappointed to see that the postmaster log part of the report
is truncated near the start of the run, so there's no way to see if
anything interesting got logged near the point of the failure.
When I run "make check" on my own OS X machine, I notice that the
postmaster.log file usually has some runs of a few dozen null bytes in
it. I suspect this is an artifact of Apple's stdio buffering
implementation when several backends are writing to the same log file.
I suppose that what happened in the above case is that some nulls got
embedded in postmaster.log, and then the file got truncated at the first
null, perhaps during the upload to the buildfarm server, or maybe it's
intact on the server but the web page is failing to display anything
past that point.
There's probably not much we can do about Apple's stdio (and I would bet
that they inherited this behavior from the BSDen anyway). What we
*could* do is
(1) encourage buildfarm owners to run the tests with logging_collector
turned on, and/or
(2) fix the buildfarm reporting mechanisms to not be fazed by nulls in
the log files.
I have no clear idea how hard either of these things is.
Well, the good news is that we actually have the data on the server, in
a temp file that will be cleaned up, but hasn't been yet. I have placed
a copy at <http://buildfarm.postgresql.org/polecat-check.log.gz>. And
thus we know that the client does exactly what you want, and the problem
is entirely on the server. That's more good news.
Now, the log_text field in our build_status_log table is text, so it's
on insertion to the database that it gets truncated. I'm thinking that I
should just escape nulls with a regex ( 's/\x00/\\0/g' or similar)
before inserting the data.
Anyone got any better ideas?
(BTW, your idea of using logging_collector won't work without
significant changes in the buildfarm client. Nice idea, though.)
cheers
andrew
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