Thread Liveness and Deadlock Risks: Lock Order and Visibility Mistakes

My Java app sometimes completely freezes without exceptions or logs. I suspect two threads are blocking each other. How should I debug and fix this?

Livelocks and deadlocks often stem from improper lock ordering or nested synchronized blocks. For example, one thread locks resource A then B, while another locks B then A—leading to indefinite lock waits. Additionally, when using shared mutable variables without proper visibility (e.g. lacking volatile), other threads may never see state changes—causing loops that never exit (“stop flags”). Fixes: • Always acquire locks in a consistent global order. • Prefer using Lock with tryLock(timeout) to avoid permanent blocking. • Avoid long-running synchronized blocks; reuse smaller critical sections. • Declare shared flags as volatile or use AtomicBoolean to ensure visibility across threads.