Following is the delete / add use case for slider based long running service. The service has instances (a.k.a. components) provided per user.
1. When a new user is added, a new component is started for that user. The idea is not to bring the existing app / components down for existing users. Say first user "user1" joins and gets component named "user1". When "user2" joins, I add "user2" component to metainfo/appconfig/resource, redeploy the package and do a "slider upgrade". This keeps "user1" component running (don't want to bring down user1) and brings user2 component up. 2. When the user is decommissioned, its component should be decommissioned (permanently, if possible) without impacting other running components. Flex zero certainly works but as you pointed, it still remembers the component; which we may not want. I tried to do a "upgrade" with that component removed from all the configs - the AM fails after trying to "locate" the component I wanted to delete. 2016-01-05 02:31:35,802 [main] ERROR main.ServiceLauncher - Exception: Cannot find role for role ID 2 java.lang.RuntimeException: Cannot find role for role ID 2 at org.apache.slider.server.appmaster.state.AppState.lookupRoleStatus(AppState.java:917) at org.apache.slider.server.appmaster.state.AppState.addRestartedContainer(AppState.java:2242) at org.apache.slider.server.appmaster.state.AppState.rebuildModelFromRestart(AppState.java:2218) at org.apache.slider.server.appmaster.state.AppState.buildInstance(AppState.java:600) at org.apache.slider.server.appmaster.SliderAppMaster.createAndRunCluster(SliderAppMaster.java:849) at org.apache.slider.server.appmaster.SliderAppMaster.runService(SliderAppMaster.java:584) at org.apache.slider.core.main.ServiceLauncher.launchService(ServiceLauncher.java:188) at org.apache.slider.core.main.ServiceLauncher.launchServiceRobustly(ServiceLauncher.java:475) at org.apache.slider.core.main.ServiceLauncher.launchServiceAndExit(ServiceLauncher.java:403) at org.apache.slider.core.main.ServiceLauncher.serviceMain(ServiceLauncher.java:630) at org.apache.slider.server.appmaster.SliderAppMaster.main(SliderAppMaster.java:2297) 2016-01-05 02:31:35,807 [main] INFO util.ExitUtil - Exiting with status 56 I may be able to live with flex for now but it would certainly be a good feature to be able to remove components permanently for use cases like above; where many users will come and go. If you think this is a valid feature ask, I can file a Jira Thanks, Manoj On Tue, Jan 5, 2016 at 2:42 AM, Steve Loughran <ste...@hortonworks.com> wrote: > > > On 5 Jan 2016, at 02:16, Manoj Samel <manojsamelt...@gmail.com> wrote: > > > > Hi, > > > > Use case needs adding and removing components dynamically. > > > > What is the proper way to remove a component ? It seems it can be done > > either by doing a "slider flex" with component count set to 0 or by > doing a > > "slider upgrade" where the component is deleted from metainfo.xml, > > appconfig.json and resources.json. > > > > Having trouble using "slider upgrade" to delete a component ... the > > documentation on upgrade is not clean on what it can / can't be used for > ... > > > Upgrade is actually for doing an update of the code of running code: it > upgrades each component one-by-one, then restarts the AM. Its goal is to > keep an app running while you update it. > > For setting a component count to zero, just use slider flex. Flexing down > should take seconds, and slider remembers where the component was. If your > component has any placement policy, then if you next flex up it will use > the most recently used locations for the initial requests > > -steve >
