Should JVM know an app is in a shutdown state when a timeout event occurs?

[David Holmes]

Re-sending to hotspot-runtime-dev at openjdk.java.net

On 13/05/2017 6:02 PM, David Holmes wrote:
> Hi,
>
> What "timeout events" are you referring to?
>
> What you show below indicates an attempt to remove a shutdown hook after
> the shutdown sequence has started - that is all in the JDK library code,
> nothing to do with hotspot.
>
> Cheers,
> David
>
> On 13/05/2017 8:29 AM, 陈雨亭 wrote:
>> I recently observed that there is a minor difference between HotSpot and
>> IBM's J9 when they process
>> the timeout events. I downloaded the dacapo benchmark
>> (http://dacapobench.org/) and ran
>>        "timeout 20s java Harness avrora"
>> . J9 sometimes throws a (java.lang.IllegalStateException: Shutdown in
>> progress) while HotSpot cannot.
>> The IllegalStateException may be thrown by J9 when
>> Runtime.getRuntime().removeShutdownHook(shutdownThread)
>> (see line 103, avrora.actions.SimAction) is executed and at the same time
>> the timeout event
>> arrives.
>>
>> In order to reproduce the event, I slightly rewrote avrora.Main.main a
>> little so that avrora.Main.runAction
>> will be called for 30 times. I also ran the command "timeout 20s java
>> Harness avrora" for 30+ times
>> so that Runtime.getRuntime().removeShutdownHook(shutdownThread) (the
>> code at
>> line 103, avrora.actions.SimAction)
>> is running when "timeout 20s java" completes.
>>
>> It seems that when the timeout event occurs, the app is in a shutdown
>> state.
>> J9 is able to detect it, while
>> HotSpot may miss catching it.
>>
>> I wonder what can be the real cause of the difference, the JVMs, or
>> the API
>> implementations (i.e., Runtime.
>> getRuntime().addShutdownHook), or the application itself. Which JVM is
>> correct? Actually when the
>> timeout event occurs, HotSpot will terminate without executing the
>> following
>> statements, while J9 throws
>> the exception and enters the exception handling block.
>>
>> avrora.actions.SimAction
>> 84        public void run(String[] args) throws Exception {
>> 85            SimUtil.REPORT_SECONDS = REPORT_SECONDS.get();
>> 86            SimUtil.SECONDS_PRECISION = (int)SECONDS_PRECISION.get();
>> 87
>> 88            simulation = Defaults.getSimulation(SIMULATION.get());
>> 89            simulation.process(options, args);
>> 90
>> 91            ShutdownThread shutdownThread = new ShutdownThread();
>> 92            Runtime.getRuntime().addShutdownHook(shutdownThread);
>> 93            printSimHeader();
>> 94            try {
>> 95                startms = System.currentTimeMillis();
>> 96                simulation.start();
>> 97                simulation.join();
>> 98            } catch (Throwable t) {
>> 99                exitSimulation(t);
>> 100
>> Runtime.getRuntime().removeShutdownHook(shutdownThread);
>> 101            } finally {
>> 102                exitSimulation(null);
>> 103
>> Runtime.getRuntime().removeShutdownHook(shutdownThread);
>> 104            }
>> 105        }
>>
>> The exception message is given as the follows:
>>
>> java.lang.reflect.InvocationTargetException
>> java.lang.reflect.InvocationTargetException
>>     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>>     at
>> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:95
>>
>> )
>>     at
>> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl
>>
>> .java:55)
>>     at java.lang.reflect.Method.invoke(Method.java:508)
>>     at org.dacapo.harness.Avrora.iterate(Avrora.java:42)
>>     at org.dacapo.harness.Benchmark.run(Benchmark.java:166)
>>     at org.dacapo.harness.TestHarness.runBenchmark(TestHarness.java:218)
>>     at org.dacapo.harness.TestHarness.main(TestHarness.java:171)
>>     at Harness.main(Harness.java:17)
>> Caused by: java.lang.IllegalStateException: Shutdown in progress
>>     at
>> java.lang.ApplicationShutdownHooks.remove(ApplicationShutdownHooks.java:93)
>>
>>     at java.lang.Runtime.removeShutdownHook(Runtime.java:250)
>>     at avrora.actions.SimAction.run(SimAction.java:103)
>>     at avrora.Main.runAction(Unknown Source)
>>     at avrora.Main.main(Unknown Source)
>>     ... 9 more
>>