Hi, What if ceph-mgr modules could actually depend on each other. That way, we could have a single cherrypy module and other modules could depend on the cherrypy module. The cherrypy module would redirect requests to the corresponding module. Would that be an option? I know nothing about the ceph-mgr architecture, so ignore my suggestion if does not make sense at all. Ricardo Dias > On 11 Apr 2017, at 11:41, Tim Serong <tserong@xxxxxxxx> wrote: > > Hi All, > > We have a problem using cherrypy in mgr modules. Specifically, multiple > modules that use cherrypy stomp on each other. I discovered this while > playing with John's guilolz experiment > (https://github.com/ceph/ceph/pull/13725). > > Both rest and guilolz modules follow this pattern: > > cherrypy.config.update({'server.socket_port': ....}) > cherrypy.tree.graft(...) # or cherrypy.tree.mount(...) > cherrypy.engine.start() > cherrypy.engine.block() > > So: > > - They're both first setting the port to listen on globally. > - They both eat the whole web namespace (graft/mount). > - They both call cherrypy.engine.start() to start the server. > > In each of the above cases, the first module loaded will win and the > other won't (or, it might be racey and you'll kinda get a mix?). For > example, the second call to cherrypy.engine.start() fails complaining it > can't be called more than once from the same thread. > > I'm not sure how best to deal with this. Assuming we *do* want it to be > possible for multiple modules that provide a web service to be loaded > simultaneously, we need to: > > - not set the port globally. > - not stomp on each others namespaces. > - only call cherrypy.engine.start() once. > > You can have multiple cherrypy servers listening on different ports, so > that gets us part of the way there, e.g.: > > from cherrypy._cpserver import Server > server = Server() > server.socket_port = .... # whatever > server.subscribe() > > But, this doesn't fix the namespace eating problem. That might be > doable with cherrypy virtualhosts > (http://tools.cherrypy.org/wiki/VirtualHosts), but I haven't > experimented further with that yet. > > Also, those subscribe()s have to happen before the > cherrypy.engine.start() call or they have no effect. One way to do that > would be to have some magic cherrypy module which is always loaded last > to start the engine, but that might be ugly. > > Another option might be to have a separate python interpreter per module > (can't stomp on each other then, right?) but that might be too resource > intensive. > > Thoughts? > > Thanks, > > Tim > -- > Tim Serong > Senior Clustering Engineer > SUSE > tserong@xxxxxxxx > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html >
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