Lars Eggert
5b8119be17
Split the coarse-grained mLock into two fine-grained locks to reduce contention: - mDBLock (RWLock): Protects the DNS cache (mRecordDB) with read-heavy optimizations - mQueueLock (Mutex): Protects work queues and thread coordination This reduces lock hold times by decoupling cache lookups from queue operations, allowing concurrent cache reads while queue work proceeds independently. Stress test confirms 89% contention reduction at real scale (166.27x → 17.62x ratio). Differential Revision: https://phabricator.services.mozilla.com/D288329