1.  Thomas Ball Principal Researcher Microsoft Corporation  Sebastian Burckhardt Researcher Microsoft Corporation  Madan Musuvathi Researcher Microsoft Corporation  Shaz Qadeer Senior Researcher Microsoft Corporation TL58

4.  Madan Musuvathi Researcher Microsoft Corporation

6.  Madan Musuvathi Researcher Microsoft Corporation

7. CAP Memory Model bugs Memory Model bugs Monitors Coverage Repro Testing Data races Data races Debugging Visualization Unmanaged Program Unmanaged Program Windows Managed Program Managed Program.NET CLR Record the interleaving executed Drive the program along an interleaving Record the interleaving executed Drive the program along an interleaving

10. Kernel: Threads, Scheduler, Synchronization Objects Kernel: Threads, Scheduler, Synchronization Objects While(not done) { TestScenario() } While(not done) { TestScenario() } TestScenario() { … } Program CHESS CHESS runs the scenario in a loop Every run takes a different interleaving Every run is repeatable Win32/.NET Uses the CAP scheduler To control and direct interleavings Detect Assertion violations Deadlocks Dataraces Livelocks CAP

11. x = 1; … x = k; x = 1; … x = k; x = 1; … x = k; x = 1; … x = k; … n threads k steps each Goal: Scale CHESS to large programs (large k)

12. x = 1; if (p != 0) { x = p->f; } x = 1; if (p != 0) { x = p->f; } x = 1; if (p != 0) { x = 1; if (p != 0) { x = p->f; } x = p->f; } p = 0; Thread 1Thread 2 preemption non-preemption

13. x = 1; … x = k; x = 1; … x = k; x = 1; … x = k; x = 1; … x = k; … n threads k steps each

14.  Thomas Ball Principal Researcher Microsoft Corporation

21. EnterCS(cs) if (p != 0) { x = p->f; } LeaveCS(cs) EnterCS(cs) if (p != 0) { x = p->f; } LeaveCS(cs) p = 0; Thread 1Thread 2

25. flag1 = true; if( !flag2 ) DoWork(); flag1 = true; if( !flag2 ) DoWork(); flag2 = true; if( !flag1 ) DoWork(); flag2 = true; if( !flag1 ) DoWork(); Thread 1Thread 2 // initial state volatile bool flag1 = false; volatile bool flag2 = false; // initial state volatile bool flag1 = false; volatile bool flag2 = false;

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