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General Rust

• Rust ownership / borrow rules / lifecycles
• Smart pointers - Box, RefCell
• Traits and trait bounds
• Pattern matching
• Unsafe
• Unwrap
• ARC / Drop order / how nested structs are managed
• RAII
• Dynamic dispatch / static dispatch / monomorphism / polymorphism
• Iteration / streams
• Error handling (lack of exceptions)
• Modules and visibility rules
• Dependency management
  • Semver
  • Cargo
• Useful crates (e.g. Dashmap)
• Clippy
• Macros (time-permitting)

Async Rust

• Concept of green threads
• Issues with blocking code / per-request thread model / context switches overhead
• Linear code, much simpler to understand than chained callbacks
• Understanding cooperative scheduling
  • Futures / polling: explain how poll() works, wakers, state machine(?)
  • What does it desugar into ?
  • Tokio executor: work stealing / LIFO slot optimization
  • Single epoll task (explain polling multiple file descriptors)
• Caveats of cooperative scheduling
  • High poll times (10us as a rule of thumb), CPU intensive tasks
  • Using blocking code
  • Blocking indefinitely one task is undefined behaviour, it might hang your application indefinitely
  • Never yielding
  • Task cancellation
  • Explain that disk I/O operations are emulated through spawn_blacking
• Tokio
  • Tokio single-threaded / multi-threaded runtimes
  • Channel types (mpsc, broadcast)
• Async traits
• Send / Sync
• Pin / Unpin ??

Debugging / profiling / benchmarking

• Tools/techniques for profiling running code
  • Flamegraphs
• Valgrind
• Benchmarking (benches directory?)
• Troubleshoot high memory usage: jemalloc / massif / dhat
• Tokio console demo
• Debugging core dumps with gdb
• Tokio runtime metrics