On Tue, 2011-08-23 at 14:37 -0700, Adam Williamson wrote: > On Tue, 2011-08-23 at 17:28 -0400, Tom Lane wrote: > > Simo Sorce <s...@redhat.com> writes: > > > ... If instead the socket is listening but not really accepting and > > > processing requests, then yes, you can have a deadlock. > > > > > So socket activation is not transparent by any means and needs to be > > > handled very carefully in terms of circular dependencies as they may > > > actually introduce deadlocks that weren't there before. > > > > Yeah. Another way in which socket activation is not transparent is that > > code might try to determine whether the service is running by seeing > > whether a connection attempt succeeds. In such a case, having the > > service autostart is absolutely *not* the desired outcome. Both mysql > > Why not? > > If the service is enabled but the daemon not currently running, is it so > terrible for a connection test to cause the daemon to start? Remember, > in systemd logic 'service enabled with socket activation, daemon not > currently running' is effectively an 'on' state, not an 'off' state. If > you wanted the database to be 'off' you should have the service > disabled, and in that case, the ping test wouldn't cause the daemon to > start.
It generally is a bad idea to automatically restart a database based on a random connection. There many reasons why you may have stopped the db (or it may have stopped itself) and requires inspection before attempting a new restart. Having to battle with socket activation while in a critical situation is not a good idea. Simo. -- Simo Sorce * Red Hat, Inc * New York -- devel mailing list devel@lists.fedoraproject.org https://admin.fedoraproject.org/mailman/listinfo/devel
