Here is current work on stepping over a signal, the race condition involved is: inside frysk-core: ./TestRunner -debug frysk.stepping.SteppingEngine=FINE frysk.stepping.TestStepping.testStepOverSignal There was 1 error: 1) testStepOverSignal(frysk.stepping.TestStepping)java.lang.RuntimeException: {frysk.proc.live.LinuxPtraceTask@327b6455,pid=29497,tid=29497,state=detaching} in state "detaching" did not handle handleStoppedEvent SIGTRAP(5) at frysk.proc.live.State.unhandled(TestRunner) at frysk.proc.live.LinuxPtraceTaskState$2.handleStoppedEvent(TestRunner) at frysk.proc.live.LinuxPtraceTask.processStoppedEvent(TestRunner) at frysk.proc.live.LinuxWaitBuilder.stopped(TestRunner) at frysk.sys.Wait.wait(TestRunner) at frysk.sys.Wait.wait(TestRunner) at frysk.event.WaitEventLoop.block(TestRunner) at frysk.event.EventLoop.runEventLoop(TestRunner) at frysk.event.EventLoop.runPolling(TestRunner) at frysk.testbed.TestLib.assertRunUntilStop(TestRunner) at frysk.testbed.TestLib.assertRunUntilStop(TestRunner) at frysk.stepping.TestStepping.testStepOverSignal(TestRunner) at frysk.junit.Runner.runCases(TestRunner) at frysk.junit.Runner.runTestCases(TestRunner) at TestRunner.main(TestRunner) happens quite frequently but every once in a while get a pass