paul at nfg
Jul 16, 2009, 3:40 AM
Post #5 of 5
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Piotr Wadas wrote:
>
> Paul J Stevens wrote:
>> We're using a single, global database connection pool. Since dbmail
>>
>
> And how exactly database connection pool works ? How open connections
> are reused between threads? My guess - there's a connection pool, which
> allocate
> _int_max_db_connections_ of available connections.
Not quite. max_db_connections is the maximum number of connections
maintained by a single connection pool, a number much larger than the
number of connections created initially on startup.
> What I want to know is
> how connections are reused by different threads? Let's say pop3 daemon has
> for the
> moment 100 open pop3 sessions. When pop3 client issue a command, the daemon
> uses db connection, and the command is completed with some internally
> processed
> query result. Now, if in the meantime another thread (pop3 client), issue
> another command, the command (thread) uses first free connection, or if all
> possible
> connections are doing something, the command is delayed (actually for
> miliseconds) until there's a connection available to be used with command
> - is it this, how it works ?
This is all handled by libzdb. The number of connections will scale as
required by the query load generated by dbmail.
I've tested with 100-200 concurrent very active imap clients using
imaptest, and the number of database connections fluctuated between 5
and 10.
--
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Paul Stevens paul at nfg.nl
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