osgi.enroute.scheduler.simple.provider: NPE at startup when bundle with CronJob is started before scheduler bundle

[karelhaeck]

At startup a NPE occurs in InterschedulerImpl at line 90 because the addSchedule method is called by SCR before the activate method.

A simple fix is to drop the activate method and initialize the ScheduledExecutorService at field declaration.

[bjhargrave]

Can you please provide a full stack trace? This may be a thread safety issue where one thread calls activate which writes the executor field while another thread calls after which reads the executor field.

[karelhaeck]

It is not a thread issue, simply the fact that SCR calls the addSchedule before the activate for any existing CronJog services at component activation time. (I should have stressed that I am using the whiteboard approach for scheduling services).
Easy to reproduce if you stop and then start the scheduler bundle while you have CronJob Services with a valid CRON property.
Stack trace:
okt 19, 2016 3:14:19 PM osgi.enroute.scheduler.simple.provider.InternalSchedulerImpl addSchedule
SEVERE: Invalid cron expression 0 * * * * ? from {service.id=108, objectClass=[Ljava.lang.String;@1b934c2d, component.name=eu.vandevelde.playground.impl.CronSample, cron=0 * * * * ?, service.scope=bundle, component.id=61, service.bundleid=40}
java.lang.NullPointerException
at osgi.enroute.scheduler.simple.provider.InternalSchedulerImpl.after(InternalSchedulerImpl.java:90)
at osgi.enroute.scheduler.simple.provider.InternalSchedulerImpl.at(InternalSchedulerImpl.java:285)
at osgi.enroute.scheduler.simple.provider.InternalSchedulerImpl.schedule(InternalSchedulerImpl.java:211)
at osgi.enroute.scheduler.simple.provider.InternalSchedulerImpl.schedule(InternalSchedulerImpl.java:269)
at osgi.enroute.scheduler.simple.provider.InternalSchedulerImpl$Cron.(InternalSchedulerImpl.java:296)
at osgi.enroute.scheduler.simple.provider.InternalSchedulerImpl.addSchedule(InternalSchedulerImpl.java:317)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.apache.felix.scr.impl.inject.BaseMethod.invokeMethod(BaseMethod.java:224)
at org.apache.felix.scr.impl.inject.BaseMethod.access$500(BaseMethod.java:39)
at org.apache.felix.scr.impl.inject.BaseMethod$Resolved.invoke(BaseMethod.java:617)
at org.apache.felix.scr.impl.inject.BaseMethod.invoke(BaseMethod.java:501)
at org.apache.felix.scr.impl.inject.BindMethod.invoke(BindMethod.java:655)
at org.apache.felix.scr.impl.manager.DependencyManager.doInvokeBindMethod(DependencyManager.java:1722)
at org.apache.felix.scr.impl.manager.DependencyManager.open(DependencyManager.java:1556)
at org.apache.felix.scr.impl.manager.SingleComponentManager.createImplementationObject(SingleComponentManager.java:260)
at org.apache.felix.scr.impl.manager.SingleComponentManager.createComponent(SingleComponentManager.java:108)
at org.apache.felix.scr.impl.manager.SingleComponentManager.getService(SingleComponentManager.java:906)
at org.apache.felix.scr.impl.manager.SingleComponentManager.getServiceInternal(SingleComponentManager.java:879)
at org.apache.felix.scr.impl.manager.AbstractComponentManager.activateInternal(AbstractComponentManager.java:748)
at org.apache.felix.scr.impl.manager.AbstractComponentManager.enableInternal(AbstractComponentManager.java:674)
at org.apache.felix.scr.impl.manager.AbstractComponentManager.enable(AbstractComponentManager.java:429)
at org.apache.felix.scr.impl.manager.ConfigurableComponentHolder.enableComponents(ConfigurableComponentHolder.java:657)
at org.apache.felix.scr.impl.BundleComponentActivator.initialEnable(BundleComponentActivator.java:341)
at org.apache.felix.scr.impl.Activator.loadComponents(Activator.java:403)
at org.apache.felix.scr.impl.Activator.access$200(Activator.java:54)
at org.apache.felix.scr.impl.Activator$ScrExtension.start(Activator.java:278)
at org.apache.felix.utils.extender.AbstractExtender.createExtension(AbstractExtender.java:259)
at org.apache.felix.utils.extender.AbstractExtender.modifiedBundle(AbstractExtender.java:232)
at org.osgi.util.tracker.BundleTracker$Tracked.customizerModified(BundleTracker.java:482)
at org.osgi.util.tracker.BundleTracker$Tracked.customizerModified(BundleTracker.java:415)
at org.osgi.util.tracker.AbstractTracked.track(AbstractTracked.java:232)
at org.osgi.util.tracker.BundleTracker$Tracked.bundleChanged(BundleTracker.java:444)
at org.apache.felix.framework.util.EventDispatcher.invokeBundleListenerCallback(EventDispatcher.java:913)
at org.apache.felix.framework.util.EventDispatcher.fireEventImmediately(EventDispatcher.java:834)
at org.apache.felix.framework.util.EventDispatcher.fireBundleEvent(EventDispatcher.java:516)
at org.apache.felix.framework.Felix.fireBundleEvent(Felix.java:4544)
at org.apache.felix.framework.Felix.startBundle(Felix.java:2166)
at org.apache.felix.framework.BundleImpl.start(BundleImpl.java:977)
at org.apache.felix.gogo.command.Basic.start(Basic.java:739)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.apache.felix.gogo.runtime.Reflective.invoke(Reflective.java:137)
at org.apache.felix.gogo.runtime.CommandProxy.execute(CommandProxy.java:82)
at org.apache.felix.gogo.runtime.Closure.executeCmd(Closure.java:480)
at org.apache.felix.gogo.runtime.Closure.executeStatement(Closure.java:406)
at org.apache.felix.gogo.runtime.Pipe.run(Pipe.java:108)
at org.apache.felix.gogo.runtime.Closure.execute(Closure.java:182)
at org.apache.felix.gogo.runtime.Closure.execute(Closure.java:119)
at org.apache.felix.gogo.runtime.CommandSessionImpl.execute(CommandSessionImpl.java:94)
at org.apache.felix.gogo.shell.Console.run(Console.java:66)
at org.apache.felix.gogo.shell.Shell.console(Shell.java:212)
at org.apache.felix.gogo.shell.Shell.gosh(Shell.java:137)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.apache.felix.gogo.runtime.Reflective.invoke(Reflective.java:137)
at org.apache.felix.gogo.runtime.CommandProxy.execute(CommandProxy.java:82)
at org.apache.felix.gogo.runtime.Closure.executeCmd(Closure.java:480)
at org.apache.felix.gogo.runtime.Closure.executeStatement(Closure.java:406)
at org.apache.felix.gogo.runtime.Pipe.run(Pipe.java:108)
at org.apache.felix.gogo.runtime.Closure.execute(Closure.java:182)
at org.apache.felix.gogo.runtime.Closure.execute(Closure.java:119)
at org.apache.felix.gogo.runtime.CommandSessionImpl.execute(CommandSessionImpl.java:94)
at org.apache.felix.gogo.shell.Activator$StartShellJob.run(Activator.java:179)
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
at java.util.concurrent.FutureTask.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

[bjhargrave]

Thanks for the stacktrace. There is definitely a bug in that the bind methods depend upon state set by the activate method. And the bind methods can be called before the activate method.