Concurrent Ruby

### Summary `Concurrent::AtomicReference#update` can enter a permanent busy retry loop when the current value is `Float::NAN`. The issue is caused by the interaction between: - `AtomicReference#update`, which retries until `compare_and_set(old_value, new_value)` succeeds. -…

### Summary `Concurrent::ReadWriteLock#release_write_lock` does not verify that the calling thread acquired the write lock. Any thread with access to the lock object can release an active write lock held by another thread. A second writer can then enter its critical section…

### Summary `Concurrent::ReentrantReadWriteLock` can incorrectly grant a write lock after one thread acquires the read lock 32,768 times. The lock stores a thread's local read and write hold counts in one integer. The low 15 bits are used for the read hold count, and bit 15 is…