Detecting Data Races in Multi-Threaded Programs Slide 1 / 31

1. Data races are easy to cause and hard to debug. 2. We can't detect all data races. 3. Detection of feasible races relies on detection of apparent data races. 4. Data race detection tools are either static or dynamic (on-the-fly and postmortem). Slide 2 / 31 Key Points Cont. 5. Data races can be prevented by following a locking discipline. 6. Commonly used detection algorithms are Lockset and DJIT (Happens-Before). 7. Lockset maintains a set of candidate locks for each shared memory location. If a shared location is accessed when this set is empty, there has been a violation of the locking discipline. Slide 3 / 31 Key Points Cont. 8. Lockset is vulnerable to false alarms. 9. DJIT uses a logging mechanism. Every shared memory access is logged to see that it “happens before ” prior accesses to the same location. 10. DJIT is dependent on the scheduler and thread interleaving. 11. Combining happens-before with Lockset can improve detection accuracy