On Wed, 24.08.11 10:45, Tom Lane (t...@redhat.com) wrote: > > Reindl Harald <h.rei...@thelounge.net> writes: > > Am 23.08.2011 23:28, schrieb Tom Lane: > >> there's no other way for "mysqladmin ping" to work, for example > > > and where is the problem? > > I'm not planning on repeating myself either, but: a database > *monitoring* tool, as opposed to a vanilla client, needs to know whether > the database is in fact up. Autostarting the DB in response to a > monitoring probe is the wrong behavior for that.
Are you sure it is? The thing is that when using socket activation it is merely an implementation detail when a service is actually really started. If you get a response you get a response and that's what you probably want to monitor. Whether the backing service has been running all the time or was just started due to your request shouldn't really matter -- unless of course you actually really want to monitor the service itself and not just whether it responds. But in that case it's probably a good idea to ask systemd for the service's status, since it will provide you with a lot of interesting data, including timestamps and so on. So, my claim would be that if you want to monitor whether a service responds then the backing implementation of it should be asbtract to you and it doesn't matter whether a service is started, or already running for that. And if you want to monitor the service itself then it's a good idea to make use of the monitoring data systemd keeps and hence you probably should talk to systemd directly in your monitoring tool. I think it's really important to know what you actually want to monitor, and then figure out how to do it best. > I do not really care whether you believe that that's a problem or not; > it is in my eyes, and as the responsible engineer, I'm not going to > produce a broken database package. I do believe socket activation is interesting for SQL servers, but lazy activation of SQL servers makes little sense. One should not conflate socket activation with lazy socket activation. The latter is only interesting for a select few of services which are very seldom used like CUPS or sshd which are usually only access less than 1/h. Socket activation brings a lot of advantages, lazy activation is only one small one. More interesting are the paralellization or the fact that we can get rid of explicitly configured dependencies and suchlike. Lennart -- Lennart Poettering - Red Hat, Inc. -- devel mailing list devel@lists.fedoraproject.org https://admin.fedoraproject.org/mailman/listinfo/devel
