Re: Read Waiters growing

[Quanah Gibson-Mount <quanah@zimbra.com>]

--On Friday, February 26, 2010 9:46 AM +0100 Peter Mogensen <apm@mutex.dk> 
wrote:

> Hi,
>
> I see a strange thing in cn=Monitor. Suggestions needed.
>
> I have a huge database, and performance is great as long as olcReadOnly
> is TRUE.
> But a soon as I enable writes, the number of Read Waiters are growing,
> even though there's no or very few Write waiters.
>
> # Read, Waiters, Monitor
> dn: cn=Read,cn=Waiters,cn=Monitor
> monitorCounter: 311
>
> # Write, Waiters, Monitor
> dn: cn=Write,cn=Waiters,cn=Monitor
> monitorCounter: 0
>
> # Current, Connections, Monitor
> dn: cn=Current,cn=Connections,cn=Monitor
> monitorCounter: 210
>
> I have idletime=120 and connections do around 30 reads each before they
> are retired, but not many writes. Like this:
>
> # Connection 5389, Connections, Monitor
> dn: cn=Connection 5389,cn=Connections,cn=Monitor
> monitorConnectionNumber: 5389
> monitorConnectionOpsReceived: 32
> monitorConnectionOpsExecuting: 0
> monitorConnectionOpsPending: 0
> monitorConnectionOpsCompleted: 32
> monitorConnectionGet: 32
> monitorConnectionRead: 32
> monitorConnectionWrite: 0
>
> It's slapd 2.4.21, BDB 4.8.26 and back_bdb.
>
> Any hint to what could cause that many read-waiters, but only while
> writing is enabled and even though there's not that many writes?

It could be a bug in back-monitor...

--Quanah

--

Quanah Gibson-Mount
Principal Software Engineer
Zimbra, Inc
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