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OpenHFT / Java-Thread-Affinity

Bind a java thread to a given core
http://chronicle.software/products/thread-affinity/
Apache License 2.0
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Race condition in acquireLock #81

Closed nicktindall closed 2 years ago

nicktindall commented 3 years ago

When multiple processes are attempting to acquire the same lock, the check to see if the core can be reserved (canReserve) and the subsequent locking of the core (updateLockForCurrentThread) are done as two separate steps.

https://github.com/OpenHFT/Java-Thread-Affinity/blob/ac876e3647665acb266c19f775274c92dcd0e079/affinity/src/main/java/net/openhft/affinity/LockInventory.java#L109-L112

The locking of the core logs and swallows exceptions thrown in the process of locking, meaning if two threads pass the canReserve check, while it's reservable they will both go on to "lock" the core:

https://github.com/OpenHFT/Java-Thread-Affinity/blob/ac876e3647665acb266c19f775274c92dcd0e079/affinity/src/main/java/net/openhft/affinity/LockCheck.java#L112-L121

Meaning you end up with multiple threads locked to a single core. The check and lock should be atomic, that will prevent this scenario.

hft-team-city commented 2 years ago

Released in Java-Thread-Affinity-3.21ea81, BOM-2.22ea49