Learning paths / Shared state, three languages

Shared state, three languages

The same lost update in Java, Go and Rust, then the collections and maps that break the same way.

1. 1Why count++ loses updatesJava · BasicsTwo threads each run count++ once. The result can be 1, not 2.
2. 2Why count++ loses updates in goroutinesGo · BasicsTwo goroutines each run count++ once. The result can be 1, not 2.
3. 3Sharing a counter between threads with Arc<Mutex<T>>Rust · BasicsTwo threads add 1 to a shared counter. The second waits in lock() until the first drops its guard.
4. 4Thread-safe collectionsJava · IntermediateTwo threads add to one ArrayList. Both write into the same slot, and one element is lost.
5. 5fatal error: concurrent map writes, explainedGo · IntermediateTwo goroutines write one plain map at the same time. The Go runtime notices and stops the whole program.
6. 6DeadlockJava · IntermediateT1 holds A and wants B. T2 holds B and wants A. Each waits for the other, forever.

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