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10.1 Deadlock - Coggle Diagram

- - - - Acceptable semantic changes
      - Protocols to restrict access post-open call
        
        E.g., set a "shutting down" state before releasing lock
- - - - Acquire locks in a fixed global order
      - Requires global analysis of locking behavior
      - Local inspections not sufficient
  - - - Use System.identityHashCode for object order
      - Handle hash collisions with a tie-breaking lock
        
        Ensures only one thread does arbitrary ordering
        
        Prevents deadlock if used consistently
    - - Simplifies ordering, no tie-breaking lock needed
  - - - Alien method may:
        
        Hold other locks
        
        Block unexpectedly
      - → Liveness risk
  - - - E.g., two database pools: threads hold one and wait on the other
    - - Inconsistent request order
      - High concurrency
    - - Task A waits for Task B (or vice versa)
      - Common with bounded thread pools and interdependent tasks