CORAL connection service configuration


Connection timeout

The connection timeout parameter determines after how long an "idle" physical connection is marked as "expired" and becomes a candidate to be cleaned up (i.e. closed) by the connection pool automatic cleanup thread.

The connection timeout parameter is NOT the connection pool automatic cleanup period! The latter is described in the next section.

Note that there will be no automatic cleanup thread if connectionTimeOut() is 0, even if isPoolAutomaticCleanUpEnabled() is true! See coral::ConnectionService::ConnectionPool::startPool(): the thread is not started if this parameter is 0.

[Question: is this why Marco's patch in COOL for disabling the connection pool cleanup also includes a change in this parameter? See task #3546. It would have been enough to either disable the cleanup or set the connection timeput to 0: was it really necessary to do both? YES it was necessary to do both because if you ALSO set the connection timeout to 0 (see this cvs diff), then a connection is closed mmediately when the last user session is closed: connection sharing will allow new sessions on a connectin where there is already one session, but every idle connection is immediately closed? Well, with disabled, then connection timeoput=0 is stronger: but ifconnection timeout=0 anyway, is there any observed difference if enabled or disabled? Probably not, but then of course it is better to disable it if thethread is useless!]

[Question: what happens if the value isPoolAutomaticCleanUpEnabled() is changed half-way in an application? Is the thread started?...]

Connection pool automatic cleanup period

The connection pool automatic cleanup period determines the frequency with which the connection pool checks whether any of its idle connections are expired and can be closed.

Until CORAL_2_3_11 included there was no way to change the default value of this parameter (which was hardcoded to 10 seconds). More recently the possibility to change the default value via the environment variable CORAL_CONNECTIONPOOL_CLEANUPPERIOD has been added (see bug #72002).

-- AndreaValassi - 29-Aug-2010

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Topic revision: r1 - 2010-08-29 - AndreaValassi
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