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view src/tests/gov/nasa/jpf/test/mc/threads/JPF_gov_nasa_jpf_test_mc_threads_ExceptionalThreadChoiceTest.java @ 24:6774e2e08d37
the fix I would have liked to avoid - apparently hotspot internally does nested locking during class init, which can lead to deadlocks such as described in http://ternarysearch.blogspot.ru/2013/07/static-initialization-deadlock.html. Actually, it's not a regular deadlock since core dumps still list the threads as runnable, althouth it doesn't seem to be a livelock either. In any case, it can be simulated by nested locking and clinit execution, and it is such a serious defect that we want to be able to catch it. The general mechanism is to replace the disparate (but properly ordered) direct clinit calls of the generic ClassInfo.initializeClass() with a single sythetic method that includes all required locking (bottom up), clinit calls / class status change (top down), and unlocking (top down). We also need to add a synthetic insn to defer changing the class status of classes that don't have clinits(), or otherwise the correct lock/unlock order will not amount to anything if the hierarchy is entered through one of the clinit-absent classes. Now we get proper deadlocks if there are concurrent cyclic dependencies during class resolution. However, this can be such a state exploder that we certainly don't want this as the default behavior, especially since it probably is hotspot specific. Nested class init locking is therefore controlled by jvm.nested_init and respective jvm.nested_init.include/exclude options. Added a NestedInitTest to demonstrate use. Thanks to Lilia Abdulina for bringing this long forgotten issue up
In the wake of nested locks, there were a number of cases to fix that implicitly relied on absent clinits because clients were not properly checking for re-execution (most notably java.util.Exchanger). This mostly came in through MJIEnv.newObject/ElementInfo. We might turn ClinitRequired into a handled exception at some point, to catch such cases during compilation.
Added a UnknownJPFClass exception (in analogy to ClinitRequired), to make clients aware of failed class load attempts/reasons.
fixed Exchanger peer, which was not giving up the lock when timing out. This is an example of a lockfree wait op that can time out. Basically, ThreadInfo.isWaiting() needs to be complemented by a isWaitingOrTimedOut(), and ElementInfo.notifies0() has to be aware of it
fixed NPE when setting report.probe_interval in tests, which was missing that it had to create a stat object
author | Peter Mehlitz <Peter.C.Mehlitz@nasa.gov> |
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date | Tue, 21 Apr 2015 00:34:15 -0700 |
parents | 61d41facf527 |
children |
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/* * Copyright (C) 2014, United States Government, as represented by the * Administrator of the National Aeronautics and Space Administration. * All rights reserved. * * The Java Pathfinder core (jpf-core) platform is licensed under the * Apache License, Version 2.0 (the "License"); you may not use this file except * in compliance with the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0. * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package gov.nasa.jpf.test.mc.threads; import gov.nasa.jpf.JPFException; import gov.nasa.jpf.annotation.MJI; import gov.nasa.jpf.vm.MJIEnv; import gov.nasa.jpf.vm.NativePeer; import gov.nasa.jpf.vm.ThreadInfo; import gov.nasa.jpf.vm.VM; import gov.nasa.jpf.vm.choice.ExceptionThreadChoiceFromSet; /** * */ public class JPF_gov_nasa_jpf_test_mc_threads_ExceptionalThreadChoiceTest extends NativePeer { @MJI public void foo____V (MJIEnv env, int objRef){ ThreadInfo ti = env.getThreadInfo(); if (!ti.isFirstStepInsn()){ String[] exceptions = { "java.net.SocketTimeoutException", "java.io.IOException" }; System.out.println(" in top half of native foo()"); VM vm = ti.getVM(); ThreadInfo[] runnables = vm.getThreadList().getAllMatching(vm.getTimedoutRunnablePredicate()); ExceptionThreadChoiceFromSet cg = new ExceptionThreadChoiceFromSet("FOO_CG", runnables, ti, exceptions); ti.getVM().getSystemState().setNextChoiceGenerator(cg); env.repeatInvocation(); } else { System.out.println(" in bottom half of native foo()"); ExceptionThreadChoiceFromSet cg = ti.getVM().getCurrentChoiceGenerator("FOO_CG", ExceptionThreadChoiceFromSet.class); if (cg == null){ throw new JPFException("wrong CG: " + cg); } String exceptionName = cg.getExceptionForCurrentChoice(); if (exceptionName != null){ env.throwException(exceptionName); } } } }