Re: [HACKERS] [pgsql-hackers] Daily digest v1.9418 (15 messages)
On Thu, Aug 27, 2009 at 01:12:20PM -0400, Robert Haas wrote: This is pretty cool, IMO. Admittedly, it does seem hard to bottle it, but you managed it, so it's not completely impossible. What you could for this kind of thing is a series of patches and driver scripts, so you build PostgreSQL with the patch, then run the driver script against it. Probably we'd want to standardize some kind of framework for the driver scripts, once we had a list of ideas for testing and some idea what it should look like. Another similar idea I've had in the back of my head for a while is to setup postgres so it is the only process in a VM. Subsequently after every single write() syscall, snapshot the filesystem and then run the recovery process over each one. It would likely take an unbeleivably long time to run, and maybe there's some trick to speed it up, but together with code coverage results it could give you good results as to the reliability of the recovery process. Probably more a research project than anything else though. Have a nice day, -- Martijn van Oosterhout klep...@svana.org http://svana.org/kleptog/ Please line up in a tree and maintain the heap invariant while boarding. Thank you for flying nlogn airlines. signature.asc Description: Digital signature
Re: [HACKERS] [pgsql-hackers] Daily digest v1.9418 (15 messages)
-- Forwarded message -- From: Kevin Grittner kevin.gritt...@wicourts.gov To: Robert Haas robertmh...@gmail.com, Bruce Momjian br...@momjian.us Date: Thu, 27 Aug 2009 09:07:05 -0500 Subject: Re: 8.5 release timetable, again Robert Haas robertmh...@gmail.com wrote: Maybe we should be looking at an expanded test suite that runs on a time scale of hours rather than seconds. if we could say that we had a regression test suite which covered X% of our code, and it passed on all Y platforms tested, that would certainly be a confidence booster, especially for large values of X. Part of the question, of course, is how to build up such a regression test suite. Aren't there code coverage monitoring tools that could be run during regression tests? Sure it would take some time to review the results and fashion tests to exercise chunks of code which were missed, but at least we could quantify X and try to make incremental progress on increasing it But the fact that a piece of code was executed doesn't mean it did the right thing. If it does something subtly wrong, will we notice? Jeff
Re: [HACKERS] [pgsql-hackers] Daily digest v1.9418 (15 messages)
Jeff Janes jeff.ja...@gmail.com wrote: But the fact that a piece of code was executed doesn't mean it did the right thing. If it does something subtly wrong, will we notice? That's why it takes some time to fashion a decent test. On the other hand, if code is not being exercised at at all during the beta testing phase, it could do something dramatically wrong and we wouldn't notice. -Kevin -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] [pgsql-hackers] Daily digest v1.9418 (15 messages)
-- Forwarded message -- From: Tom Lane t...@sss.pgh.pa.us To: Robert Haas robertmh...@gmail.com Date: Thu, 27 Aug 2009 10:11:24 -0400 Subject: Re: 8.5 release timetable, again What I'd like to see is some sort of test mechanism for WAL recovery. What I've done sometimes in the past (and recently had to fix the tests to re-enable) is to kill -9 a backend immediately after running the regression tests, let the system replay the WAL for the tests, and then take a pg_dump and compare that to the dump gotten after a conventional run. However this is quite haphazard since (a) the regression tests aren't especially designed to exercise all of the WAL logic, and (b) pg_dump might not show the effects of some problems, particularly not corruption in non-system indexes. It would be worth the trouble to create a more specific test methodology. I hacked mdwrite so that it had a static int counter. When the counter hit 400 and if the guc_of_death was set, it would write out a partial block (to simulate a partial page write) and then PANIC. I have some Perl code that runs against the database doing a bunch of updates until the database dies. Then when it can reconnect again it makes sure the data reflects what Perl thinks it should. This is how I (belatedly) found and traced down the bug in the visibility bit. (What I was trying to do is determine if my toying around with XLogInsert was breaking anything. Since the regression suit wouldn't show me a problem if one existed, I came up with this. Then I found things were broken even before I started toying with it...) I don't know how lucky I was to hit open a test that found an already existing bug. I have to assume I was somewhat lucky, simply because it took a run of many hours or overnight (with a simulated crash every 2 minutes or so) to reliably detect the problem. But how do you turn something like this into a regression test? Scattering the code with intentional crash inducing code that is there to exercise the error recover parts seems like it would be quite a mess. In short: merely making the tests bigger doesn't impress me in the least. Focused testing on areas we aren't covering at all could be worth the trouble. Do you have suggestions on what other areas need it? Jeff
Re: [HACKERS] [pgsql-hackers] Daily digest v1.9418 (15 messages)
On Thu, Aug 27, 2009 at 12:47 PM, Jeff Janesjeff.ja...@gmail.com wrote: -- Forwarded message -- From: Tom Lane t...@sss.pgh.pa.us To: Robert Haas robertmh...@gmail.com Date: Thu, 27 Aug 2009 10:11:24 -0400 Subject: Re: 8.5 release timetable, again What I'd like to see is some sort of test mechanism for WAL recovery. What I've done sometimes in the past (and recently had to fix the tests to re-enable) is to kill -9 a backend immediately after running the regression tests, let the system replay the WAL for the tests, and then take a pg_dump and compare that to the dump gotten after a conventional run. However this is quite haphazard since (a) the regression tests aren't especially designed to exercise all of the WAL logic, and (b) pg_dump might not show the effects of some problems, particularly not corruption in non-system indexes. It would be worth the trouble to create a more specific test methodology. I hacked mdwrite so that it had a static int counter. When the counter hit 400 and if the guc_of_death was set, it would write out a partial block (to simulate a partial page write) and then PANIC. I have some Perl code that runs against the database doing a bunch of updates until the database dies. Then when it can reconnect again it makes sure the data reflects what Perl thinks it should. This is how I (belatedly) found and traced down the bug in the visibility bit. (What I was trying to do is determine if my toying around with XLogInsert was breaking anything. Since the regression suit wouldn't show me a problem if one existed, I came up with this. Then I found things were broken even before I started toying with it...) I don't know how lucky I was to hit open a test that found an already existing bug. I have to assume I was somewhat lucky, simply because it took a run of many hours or overnight (with a simulated crash every 2 minutes or so) to reliably detect the problem. But how do you turn something like this into a regression test? Scattering the code with intentional crash inducing code that is there to exercise the error recover parts seems like it would be quite a mess. This is pretty cool, IMO. Admittedly, it does seem hard to bottle it, but you managed it, so it's not completely impossible. What you could for this kind of thing is a series of patches and driver scripts, so you build PostgreSQL with the patch, then run the driver script against it. Probably we'd want to standardize some kind of framework for the driver scripts, once we had a list of ideas for testing and some idea what it should look like. ...Robert P.S. The subject line of this thread is not ideal. -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
