Advanced · Module 7 · Lesson 2 of 8

Mutual Exclusion: Mutexes, Deadlock Prevention, and Lock Hierarchies

Protect shared memory state with pthread mutexes, configure recursive and error-checking attributes, eliminate deadlocks via global lock ordering, and trace futex fast-paths.

ProAbout 16 minutes

By the end you can

Eliminate data races on shared memory structures using pthread_mutex_t
Configure mutex attributes including PTHREAD_MUTEX_ERRORCHECK and PTHREAD_MUTEX_RECURSIVE
Identify the four Coffman deadlock conditions and eliminate circular waits via lock hierarchies
Trace low-level atomic fast-path acquisition versus futex-backed slow-path suspension

Builds on Thread Lifecycle: pthread_create, pthread_join, and Thread Stacks.

01 · A question first

Why does incrementing a shared counter variable across four threads without a lock produce different answers on every execution, while acquiring locks in different orders across two threads freezes the entire application permanently? The answer lies in cache coherency and lock hierarchies.

Make a guess before you read on.

02 · The idea

Members only

Unlock the full lesson

This lesson is part of the membership. Join to read it in full, along with every other premium deep dive.

What's inside

Start with the problem
How the idea works
The Four Coffman Deadlock Conditions
Lock Hierarchies and Global Ordering
Why it is correct
What it costs
Pitfalls and variations
Where it is used