From: David M. Lloyd <david.lloyd(a)redhat.com&gt; To: wildfly-dev(a)lists.jboss.org Subject: Re: [wildfly-dev] Wildfly start-up as service script depends on console log to determinate start result Date: Fri, 12 Jun 2015 07:57:25 -0500 This is yet another good use case for an idea I proposed at the last couple developer meeting: the idea of configurable "availability" services, where you add a configuration which says "when these components and/or configured services are available, perform this action" where the action might be to notify a load balancer, perform a notification to humans, or even drop a file to the filesystem (which would be directly useful to this use case). Note (in case someone thinks this is a great idea and runs out to implement it right away) that when I say "configured services" I do not mean MSC service names; more like management capabilities where you have a constrained namespace and each subsystem can contribute services to this category. Also note that Java 9 adds limited support for signalling unrelated processes, though at the moment on UNIX the signals are basically limited to TERM and KILL. On 06/12/2015 07:06 AM, Jason T. Greene wrote: > >> On Jun 10, 2015, at 11:46 AM, Brian Stansberry >> <brian.stansberry(a)redhat.com&gt; wrote: >> >> So, what purpose is this fulfilling? >> >> 2) How does other software solve this problem? If it's solving a >> valid >> problem, it seems like there would be a typical solution. > > The classic UNIX solution is that the daemon forks and returns, > dropping a PID file of its child to disk, after it is done > initializing and exits with an error code when there is a problem. > > Systemd added other approaches, where a daemon can signal systemd > directly, or it can use dbus to send a message. > > The former can't be done efficiently in Java because it doesn't have > a pure fork(), only an exec. Although it would be possible to emulate > with an exec with an unacceptable hit to boot time. The latter > options are too Linux specific. > > I think the best solution would be for us to add a signaling > mechanism specifically for this purpose. We could use sun.misc.Signal > (potentially an issue on Java 9), or we could exec the kill command > to signal a process. > > We could also use a specially status file (e.g standalone.sh > --start-status-file=blah) for a script to monitor. > > Thoughts? > _______________________________________________ > wildfly-dev mailing list > wildfly-dev(a)lists.jboss.org > https://lists.jboss.org/mailman/listinfo/wildfly-dev > -- - DML _______________________________________________ wildfly-dev mailing list wildfly-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/wildfly-dev