Advanced · Module 11 · Lesson 3 of 6
Deadlock: What It Is and How std::lock Avoids It
Recognize the four deadlock conditions, reproduce opposite-order locking, and fix it with std lock and scoped_lock.
By the end you can
- Diagnose deadlock from opposite lock order and circular wait
- Apply std lock with adopt_lock for multi-mutex safety
- Prefer scoped_lock for exception-safe multi-mutex ownership
Builds on Mutual Exclusion: mutex, lock_guard and unique_lock.
01 · A question first
Two bank transfers move money between the same accounts in opposite directions. Each holds one account lock, sleeps ten milliseconds, then waits for the other lock. Both wait forever and the test harness hangs at join. What four conditions create the freeze, and which single call breaks the circle?
Make a guess before you read on.
02 · The idea
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What's inside
- Start with the freeze
- How the idea works
- Why it is correct
- Two bridges and one rule
- Pitfalls and variations
- Where it is used and what comes next
03 · Practice
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