Op 8 jun 2010, om 12:36 heeft Paul J Stevens het volgende geschreven: > Erwin Lubbers wrote: >> Hi, >> >> I'm wondering why my dbmail (2.2.13) installation is performing so slow on >> imap search and sort operations. We're using a 64 Gb/SAS MySQL server >> dedicated to dbmail as storage (around 300 Gb in use) and serveral 4 Gb >> machines for the dbmail-imap processes. >> >> I did try a session by telneting to port 143 and than the following happens: >> >> ... LOGIN "username" "password" >> >> Dbmail responsed immediatly with it's OK. Then: >> >> ... SELECT "INBOX" >> >> And again it tells within an eyeblink that there are 1039 messages in the >> INBOX. Then: >> >> ... SEARCH ALL UNDELETED > > That one should really be very fast. > >> >> This response takes 56.3 seconds (!) for those 1039 messages. And a >> >> ... SORT (DATE) US-ASCII ALL UNDELETED >> >> took 38.6 seconds. > > This one is taking too long on my server. Mostly query-bound time. > >> >> In this time there seems to be no query running on the MySQL server (or it >> must run for a very short time so my 1 second updates with mysqladmin >> doesn't seem to catch it). > > That is too weird. Normally slow response is an indication of a poorly > performing query. Did the process involved take up a lot of CPU? Try > running vmstat while your running these commands. > >> >> Anyone an idea how to improve the performance? > > Setup dbmail.conf to log slow queries, and use 'explain' to locate > missing of poorly configured indexes. And post back your findings. > >
Did try another test (with the same commands) on a server (2 Gb, 3 Ghz single core CPU, no other processes running) where only a dbmail-imapd is running on a private IP address, so there is no interference with other sessions and the results are dramatic. CPU load goes to 100% for multiple seconds (vmstat updates every second): procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 0 0 0 1979036 31396 43008 0 0 0 0 1011 7 0 0 100 0 0 0 0 1979036 31396 43008 0 0 0 0 1011 9 0 0 100 0 1 0 0 1979036 31396 43008 0 0 0 0 1025 12 28 1 71 0 1 0 0 1979036 31396 43008 0 0 0 0 1013 13 100 0 0 0 1 0 0 1979036 31396 43008 0 0 0 0 1011 9 100 0 0 0 1 0 0 1979036 31396 43008 0 0 0 0 1012 9 100 0 0 0 1 0 0 1979036 31396 43008 0 0 0 0 1011 7 100 0 0 0 1 0 0 1979036 31396 43008 0 0 0 0 1011 9 100 0 0 0 1 0 0 1979036 31396 43008 0 0 0 0 1011 9 100 0 0 0 1 0 0 1979036 31396 43008 0 0 0 0 1017 11 100 0 0 0 0 0 0 1979036 31396 43008 0 0 0 0 1031 20 18 0 82 0 0 0 0 1979036 31396 43008 0 0 0 0 1012 9 0 0 100 0 0 0 0 1979036 31396 43008 0 0 0 0 1011 7 0 0 100 0 > -- > ________________________________________________________________ > Paul Stevens paul at nfg.nl > NET FACILITIES GROUP GPG/PGP: 1024D/11F8CD31 > The Netherlands________________________________http://www.nfg.nl > _______________________________________________ > DBmail mailing list > DBmail@dbmail.org > http://mailman.fastxs.nl/cgi-bin/mailman/listinfo/dbmail _______________________________________________ DBmail mailing list DBmail@dbmail.org http://mailman.fastxs.nl/cgi-bin/mailman/listinfo/dbmail
