Deadlocks
On This Lesson 4 topics
This lesson is planned. The outline below lists the topics it will cover. The full lesson has not been published yet.
In this lesson
recognize and prevent deadlock.
Planned topics
- Deadlock: threads each hold a lock and wait for another's; none proceeds.
- Four conditions: mutual exclusion, hold and wait, no preemption, circular wait.
- Prevention: acquire locks in a global order; hold fewer locks; use
tryLockwith timeout. - Livelock and starvation are related: threads busy but no progress, or never scheduled.
- Thread dumps report deadlocks explicitly.
Draft outline details
Demonstration
transfer(a,b) and transfer(b,a) locking in opposite order; fix by locking the lower ID first.
Check your understanding
What simple rule prevents circular wait?
Show answer
Always acquire locks in the same global order.
Practice
Apply this lesson with the module's lab, exercises and quiz.
Marking a lesson complete is optional and you can undo it any time. Your progress stays in this browser.