performance degrades dramatically after a few queries
693751Jun 29 2009 — edited Jul 1 2009Hi,
I am using dbxml, but it was told that my problem is possibly more related to Berkeley DB.
I have several containers of about 4.5 Gig in file size, each containing 20.000 xml documents.
I query each container once with the same query. The first two go OK, but from then, the third, fourth etc. show response times growing to ten times or worse of the first two queries. It does not matter which containers are queried first or last. Only after recover things go OK again, until ... third, fourth query...
Cache is 6 Gig. System memory is 8 gig. Queries are read-only; eager.
Observation:
The (disk) i/o cache used by Linux is up 6-7 Gig; Memory used by applications is just over 1 Gig (where is DBs 6 gig cache?).
I/O is always between 85-99% (by the querying app.) during the run of the application, for the fast as well as the slow runs.
System:
Berkeley DB: db-4.6.21; dbxml-4-6-16;
Debian Lenny; kernel 2-6-26-1-amd64
Any suggestions are very welcome.
Regards,
wim de vries
.