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

/*
 * 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.data;

import gov.nasa.jpf.util.json.CGCreator;
import gov.nasa.jpf.util.json.Value;
import gov.nasa.jpf.util.test.TestJPF;
import gov.nasa.jpf.vm.BooleanChoiceGenerator;
import gov.nasa.jpf.vm.ChoiceGenerator;
import gov.nasa.jpf.vm.Verify;

import org.junit.Test;

/**
 *
 * @author Ivan Mushketik
 */
public class CGCreatorFactoryTest extends TestJPF {
static class TestBoolCGCreator implements CGCreator {

    @Override
	public ChoiceGenerator createCG(String id, Value[] values) {
      return new BooleanChoiceGenerator(id);
    }

  }

  class B {

    boolean b;

    public B(boolean b) {
      this.b = b;
    }

    @Override
    public boolean equals(Object o) {
      B other = (B) o;

      return this.b == other.b;
    }

  }

  @Test
  public void testAddUserDefinedCGCreator() {
    if (verifyNoPropertyViolation("+jpf-core.native_classpath+=;${jpf-core}/build/tests",
            "+jpf-core.test_classpath+=;${jpf-core.native_classpath}",
            "+cg-creators=TF:" + TestBoolCGCreator.class.getName())) {

      String json = "{"
              + "'b' : TF()"
              + "}";

      Object[] expected = {
        new B(true), new B(false)
      };

      B b = Verify.createFromJSON(B.class, json);
      JSONTest.checkValue(expected, b);
    }
  }
}