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Re: Threads Backload

Hallvard B Furuseth wrote:
Bill MacAllister writes:
In looking at some load issues on our servers we have starting recording some cn=Monitor counters for analysis. In particular we would like to understand what cn=Backload,cn=Threads,cn=Monitor contains. On our servers we have threads set to 8 and we have seen maximum backload values of 56. Does this means there are 56 connections waiting for an execution thread?

Someone else could give a better answer but...

No, it's the number of unfinished tasks submitted to the thread pool.
Each LDAP operation is submitted as a separate task - i.e. a C function
call to be performed.  With your numbers, 8 or fewer are active and the
remaining 48 are waiting for a thread to pick them up and run them.

Note that some other tasks are also submitted to the thread pool, I
don't remember quite which ones.  Listening for new connections, reading
from and closing a connection, depending on how slapd is compiled.  "Run
queue" tasks, which I don't remember what are.  Replication, maybe.

Note that in 2.4 a description appears for each thread related monitor entry. The one for backload states "Number of active plus pending threads", which is as much as I could infer from the formula that computes the return value for the call that computes the monitored value.


Ing. Pierangelo Masarati OpenLDAP Core Team

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