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Video Description
List and Dictionary will betray you. Under concurrent access, they corrupt data silently. .NET has better options built specifically for multithreading.
What you'll learn:
- Why List and Dictionary fail with threads
- System.Collections.Concurrent namespace
- ConcurrentDictionary - the thread-safe workhorse
- TryAdd, TryGetValue, TryRemove patterns
- GetOrAdd - atomic check-and-add
- AddOrUpdate - atomic modifications
- ConcurrentBag for unordered collections
- ConcurrentQueue (FIFO) and ConcurrentStack (LIFO)
- BlockingCollection for producer-consumer
- The Lazy pattern for expensive factories
Key insights:
- Regular collections + threads = silent corruption
- Concurrent collections handle locking internally
- Try methods never throw on missing keys
- GetOrAdd factory might run multiple times
- Use Lazy when factory is expensive
- BlockingCollection coordinates producers/consumers
- CompleteAdding signals no more items coming
- Still need locks for multi-operation atomicity
We'll build:
- Thread-safe cache with ConcurrentDictionary
- GetOrAdd caching pattern
- Producer-consumer file processor
- Multi-threaded word frequency counter
Next Video: Tasks - Modern Multithreading
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Chapters
- 0:00 Thread-Safe Collections
- 1:17 Regular Collections Will Betray You
- 1:44 List Under Pressure
- 2:30 The Concurrent Collection Family
- 3:25 ConcurrentDictionary Basics
- 4:10 GetOrAdd - The Atomic Pattern
- 4:32 GetOrAdd - Caching Pattern
- 4:57 AddOrUpdate - Modify Atomically
- 5:47 ConcurrentBag - Unordered and Fast
- 6:33 ConcurrentQueue and ConcurrentStack
- 6:58 BlockingCollection - Producer/Consumer
- 7:43 Complete Producer-Consumer Example
- 8:14 Common Mistakes
- 9:09 Lazy Factory Pattern
- 9:29 Choosing the Right Collection
- 10:23 Q: When Should I Still Use Locks?
- 11:05 Key Takeaways
- 12:01 Practice Challenge
Video Info
- Duration: 13:18
- Published: December 15, 2025
