Operating Systems & Concurrency

Part of the Interview Prep Roadmap. Coverage ratings are explained there.

Operating Systems

Processes vs. threads, scheduling, memory management, and deadlocks.

Coverage: rich

Resources · OSTEP — Operating Systems: Three Easy Pieces — free textbook, the standard recommendation · Linux Journey

OS Fundamentals

• Role of the operating system
• Kernel space vs. user space
• System calls

Practice

• What an operating system is and does — Sonargaon University
• Kernels: monolithic vs. microkernel — Therap
• Virtualization vs. containers — Therap
• From source file to executable — Shanghai BD, with answer
• The major parts of a CPU — Shanghai BD, with answer
• DMA, byte order, coroutine, RISC, PCB — Shanghai BD, with answer

Processes & Threads

• Process lifecycle and states
• Process vs. thread
• Context switching
• Inter-process communication

Practice

• What a process is — Therap
• Context switching — Therap
• Monitoring a running process — Therap

CPU Scheduling

• Scheduling objectives
• FCFS, SJF, round robin, and priority scheduling
• Preemptive vs. non-preemptive scheduling
• Starvation and aging

Practice

• Why process scheduling exists — Shanghai BD
• Structure for round-robin CPU time-sharing — Brain Station 23

Memory Management

• Physical vs. virtual memory
• Paging and segmentation
• Page replacement algorithms
• Thrashing and locality

Practice

• Internal fragmentation — IUBAT
• The memory hierarchy — IUBAT
• How cache memory reduces misses — World University

Synchronization & Deadlocks

• Critical sections
• Mutexes and semaphores
• Deadlock conditions
• Prevention, avoidance, and detection

Practice

• Deadlocks, and how to prevent them — bKash
• A read-then-update race — Priyo, with answer

File Systems & I/O

• File system structure
• Inodes and directories
• Disk scheduling

Practice

• Hard links vs. soft links — Therap
• The Linux filesystem hierarchy — Therap
• File permissions — Therap
• chmod 777 but still cannot modify — Therap

Linux & the Shell

• Shells and common commands
• File permissions and ownership
• Users and processes
• Shell scripting

Practice

• What a shell is, and common shells — Therap
• cd, cp, ls, grep, mv — Therap
• Finding help on the command line — Therap
• Creating a user — Therap
• Creating a file — Therap
• Write a Bash script to find a directory — Therap, with answer
• Automate config updates across servers — Therap, with answer

Concurrency & Multithreading

Thread safety, race conditions, and synchronization — what can go wrong when multiple threads touch the same state.

Coverage: thin

Resources · Java Concurrency basics — Baeldung

Concurrency Fundamentals

• Concurrency vs. parallelism
• Thread lifecycle
• Shared mutable state

Practice

• When multithreading beats multiprocessing — Therap
• How single-threaded JavaScript stays async — Exabyting
• The event loop, and libuv underneath — Exabyting

Race Conditions & Synchronization

• Race conditions
• Mutual exclusion
• Locks, monitors, and atomic operations
• Designing a thread-safe class

Practice

• A read-then-update race on a field — Priyo, with answer
• Why naive Singleton is not thread-safe — Kite Games, with answer

Coordination Patterns

• Producer-consumer
• Reader-writer
• Thread pools
• Asynchronous and non-blocking patterns

Pitfalls

• Deadlock, livelock, and starvation
• Double-checked locking
• Performance cost of synchronization

Practice

• Deadlock, and how it is resolved — bKash