Program: 55235
Project: 55235
Buggy source:
/** 
 * Cancels and removes the task represented by this vertex from the instance it is currently running on. If the task is not currently running, its execution state is simply updated to <code>CANCELLED</code>.
 * @throws InterruptedException thrown if the caller is interrupted while waiting for the response of the remote procedure call
 * @return the result of the task cancel attempt
 */
public TaskCancelResult cancelTask() throws InterruptedException {
  while (true) {
    final ExecutionState previousState=this.executionState.get();
    if (previousState == ExecutionState.CANCELED) {
      return new TaskCancelResult(getID(),AbstractTaskResult.ReturnCode.SUCCESS);
    }
    if (previousState == ExecutionState.FAILED) {
      return new TaskCancelResult(getID(),AbstractTaskResult.ReturnCode.SUCCESS);
    }
    if (previousState == ExecutionState.FINISHED) {
      return new TaskCancelResult(getID(),AbstractTaskResult.ReturnCode.SUCCESS);
    }
    if (previousState == ExecutionState.CANCELING) {
      return new TaskCancelResult(getID(),ReturnCode.SUCCESS);
    }
    if (previousState == ExecutionState.STARTING) {
      this.cancelRequested.set(true);
      if (this.executionState.get() != ExecutionState.STARTING) {
        this.cancelRequested.set(false);
        continue;
      }
      return new TaskCancelResult(getID(),AbstractTaskResult.ReturnCode.SUCCESS);
    }
    if (compareAndUpdateExecutionState(previousState,ExecutionState.CANCELING)) {
      if (this.groupVertex.getStageNumber() != this.executionGraph.getIndexOfCurrentExecutionStage()) {
        updateExecutionState(ExecutionState.CANCELED,null);
        return new TaskCancelResult(getID(),AbstractTaskResult.ReturnCode.SUCCESS);
      }
      if (previousState != ExecutionState.RUNNING && previousState != ExecutionState.FINISHING && previousState != ExecutionState.REPLAYING) {
        updateExecutionState(ExecutionState.CANCELED,null);
        return new TaskCancelResult(getID(),AbstractTaskResult.ReturnCode.SUCCESS);
      }
      final AllocatedResource ar=this.allocatedResource.get();
      if (ar == null) {
        final TaskCancelResult result=new TaskCancelResult(getID(),AbstractTaskResult.ReturnCode.NO_INSTANCE);
        result.setDescription("String_Node_Str" + this.toString() + "String_Node_Str");
        return result;
      }
      try {
        return ar.getInstance().cancelTask(this.vertexID);
      }
 catch (      IOException e) {
        final TaskCancelResult result=new TaskCancelResult(getID(),AbstractTaskResult.ReturnCode.IPC_ERROR);
        result.setDescription(StringUtils.stringifyException(e));
        return result;
      }
    }
  }
}

Fixed version (ground truth):
/** 
 * Cancels and removes the task represented by this vertex from the instance it is currently running on. If the task is not currently running, its execution state is simply updated to <code>CANCELLED</code>.
 * @throws InterruptedException thrown if the caller is interrupted while waiting for the response of the remote procedure call
 * @return the result of the task cancel attempt
 */
public TaskCancelResult cancelTask() throws InterruptedException {
  while (true) {
    final ExecutionState previousState=this.executionState.get();
    if (previousState == ExecutionState.CANCELED) {
      return new TaskCancelResult(getID(),AbstractTaskResult.ReturnCode.SUCCESS);
    }
    if (previousState == ExecutionState.FAILED) {
      return new TaskCancelResult(getID(),AbstractTaskResult.ReturnCode.SUCCESS);
    }
    if (previousState == ExecutionState.FINISHED) {
      return new TaskCancelResult(getID(),AbstractTaskResult.ReturnCode.SUCCESS);
    }
    if (previousState == ExecutionState.CANCELING) {
      return new TaskCancelResult(getID(),ReturnCode.SUCCESS);
    }
    if (previousState == ExecutionState.STARTING) {
      this.cancelRequested.set(true);
      if (this.executionState.get() != ExecutionState.STARTING) {
        this.cancelRequested.set(false);
        continue;
      }
      return new TaskCancelResult(getID(),AbstractTaskResult.ReturnCode.SUCCESS);
    }
    if (compareAndUpdateExecutionState(previousState,ExecutionState.CANCELING)) {
      if (this.groupVertex.getStageNumber() != this.executionGraph.getIndexOfCurrentExecutionStage() && previousState != ExecutionState.REPLAYING && previousState != ExecutionState.FINISHING) {
        updateExecutionState(ExecutionState.CANCELED,null);
        return new TaskCancelResult(getID(),AbstractTaskResult.ReturnCode.SUCCESS);
      }
      if (previousState != ExecutionState.RUNNING && previousState != ExecutionState.FINISHING && previousState != ExecutionState.REPLAYING) {
        updateExecutionState(ExecutionState.CANCELED,null);
        return new TaskCancelResult(getID(),AbstractTaskResult.ReturnCode.SUCCESS);
      }
      final AllocatedResource ar=this.allocatedResource.get();
      if (ar == null) {
        final TaskCancelResult result=new TaskCancelResult(getID(),AbstractTaskResult.ReturnCode.NO_INSTANCE);
        result.setDescription("String_Node_Str" + this.toString() + "String_Node_Str");
        return result;
      }
      try {
        return ar.getInstance().cancelTask(this.vertexID);
      }
 catch (      IOException e) {
        final TaskCancelResult result=new TaskCancelResult(getID(),AbstractTaskResult.ReturnCode.IPC_ERROR);
        result.setDescription(StringUtils.stringifyException(e));
        return result;
      }
    }
  }
}