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Data Structures & AlgorithmsComplexity analysis up to graphs and DP.Operating SystemsProcesses, scheduling, memory and concurrency.Database Management SystemsRelational modelling, transactions and indexing.Computer NetworksFrom wires and radio waves up to the web.

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Operating Systems

Foundations of Operating Systems3

Processes & Threads4

Inter-Process Communication3

Concurrency & Synchronization4

Race conditions and the critical section problem
Locks and mutexes — the bathroom key trick
Semaphores and monitors — counting turns and tidy rooms
The classic synchronization problems, solved from scratch

CPU Scheduling4

I/O & Disk Scheduling3

Memory Management4

Virtual Memory3

Building Your Own OS in C++6

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Operating Systems

Foundations of Operating Systems3

Processes & Threads4

Inter-Process Communication3

Concurrency & Synchronization4

Race conditions and the critical section problem
Locks and mutexes — the bathroom key trick
Semaphores and monitors — counting turns and tidy rooms
The classic synchronization problems, solved from scratch

CPU Scheduling4

I/O & Disk Scheduling3

Memory Management4

Virtual Memory3

Building Your Own OS in C++6

Learn Operating Systems Concurrency & Synchronization

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Locks and mutexes — the bathroom key trick

The simplest tool for enforcing mutual exclusion, how it's actually built on hardware, and the real cost of getting it wrong.

9 min readUpdated 2026-09-03operating-systemsconcurrencylocksmutex