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Mutex - Junior

A mutex allows one thread to update protected state at a time. Always release it, including on errors.

sequenceDiagram participant A as Loader A participant M as Mutex participant B as Loader B A->>M: lock B->>M: lock and wait A->>M: update batch; unlock M-->>B: acquired

Use with lock: in Python, defer mu.Unlock() in Go, or a guard in Rust/C++. Keep parsing and warehouse I/O outside. Protect all reads and writes that participate in the same invariant.

Continue to middle.md.

Test yourself

  1. What state does the mutex protect?
  2. Why should I/O stay outside the critical section?
  3. How does a guard prevent forgotten unlocks?