Florian Weimer wrote:
* Andi Kleen:
Has anybody contacted the Sleepycat people with a description of the
problem yet?
Berkeley DB does not call sched_yield, but OpenLDAP does in some
wrapper code around the Berkeley DB backend.
That's not the complete story. BerkeleyDB provides a
db_env_set_func_yield() hook to tell it what yield function it should
use when its internal locking routines need such a function. If you
don't set a specific hook, it just uses sleep(). The OpenLDAP backend
will invoke this hook during some (not necessarily all) init sequences,
to tell it to use the thread yield function that we selected in autoconf.
Note that (on systems that support inter-process mutexes) a BerkeleyDB
database environment may be used by multiple processes concurrently. As
such, the yield function that is provided must work both for threads
within a single process (PTHREAD_SCOPE_PROCESS) as well as between
processes (PTHREAD_SCOPE_SYSTEM). The previous comment about slapd only
needing to yield within a single process is inaccurate; since we allow
slapcat to run concurrently with slapd (to allow hot backups) we need
BerkeleyDB's locking/yield functions to work in System scope.
--
-- Howard Chu
Chief Architect, Symas Corp. http://www.symas.com
Director, Highland Sun http://highlandsun.com/hyc
OpenLDAP Core Team http://www.openldap.org/project/
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