Re:What could Go wrong with a mutex
by tialaramex on Wednesday November 03, 2021 @06:16AM
(#29092776)
Indeed. Loom is about simulating what-happens-before questions for concurrency, particularly Atomics.
Loom would show you if your program, in which you believed A must happen, then B or C, and then either D or the other of B and C; actually could sometimes result in D happening, then B, then A because you screwed up.
Safe Rust promises that your program won't have Undefined Behaviour as a result of such a mistake, but its defined behaviour might still be extremely surprising to you. From Rust's point of view, "Open fuel valve, allow hydrogen gas to flood into engine room, then start fans, then try to light pilot flame" is no less "safe" than "Check fans are running, check pilot flame on, if so open fuel valve" but you probably don't agree. People can write safe Rust abstractions and this is popular in the embedded world, but ultimately program logic is somewhere a programmer's responsibility. Maybe you want to cause explosions in the engine room.
Loom would show you if your program, in which you believed A must happen, then B or C, and then either D or the other of B and C; actually could sometimes result in D happening, then B, then A because you screwed up.
Safe Rust promises that your program won't have Undefined Behaviour as a result of such a mistake, but its defined behaviour might still be extremely surprising to you. From Rust's point of view, "Open fuel valve, allow hydrogen gas to flood into engine room, then start fans, then try to light pilot flame" is no less "safe" than "Check fans are running, check pilot flame on, if so open fuel valve" but you probably don't agree. People can write safe Rust abstractions and this is popular in the embedded world, but ultimately program logic is somewhere a programmer's responsibility. Maybe you want to cause explosions in the engine room.