Hi, On 2015-01-13 16:29:51 -0600, Merlin Moncure wrote: > On my workstation today (running vanilla 9.4.0) I was testing some new > code that does aggressive parallel loading to a couple of tables. It > ran ok several dozen times and froze up with no external trigger. > There were at most 8 active backends that were stuck (the loader is > threaded to a cap) -- each query typically resolves in a few seconds > but they were hung for 30 minutes+.
Interesting. > Had to do restart immediate as > backends were not responding to cancel...but I snapped a 'perf top' > before I did so. The results were interesting so I'm posting them > here. So far I have not been able to reproduce...FYI Can you compile postgres with -fno-omit-frame-pointer? Then, when this happens the next time, you can take a perf record -g, which will tell us which lock the contention is at. > 61.03% postgres [.] s_lock > 13.56% postgres [.] LWLockRelease > 10.11% postgres [.] LWLockAcquire That profile looks like it might end up being helped by the lwlock and/or freelist changes in 9.5. Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
