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PESSIMISTIC LOCKING

“Assume conflict will happen. Lock early.”

🧰 Mechanism:​

  • Acquire lock before accessing data
  • Other transactions block until lock is released

🟢 Pros:​

  • Safe: avoids conflicts
  • Good for high-contention systems

🔴 Cons:​

  • Can lead to deadlocks
  • Lower concurrency
  • Blocking = slower performance

🛠️ Common in:​

  • Traditional RDBMS (e.g., SELECT ... FOR UPDATE)
  • Critical sections in threads (synchronized, ReentrantLock)

References​

  • ChatGPT