Spyke
piefed.social

Wait, is rust supposed to have intrinsic race condition protection? I thought its big feature was figuring out freeing memory for the dev instead of relying on runtime solutions or manual instructions... If it's not supposed to magically fix possible race conditions, I don't know how this issue is the language's fault.

43
tylerreply
programming.dev

It’s not. It’s literally code in an unsafe block. The OP is either trolling or actually ignorant.

86

Not only unironic but explained in the doc you referenced:

However Rust does not prevent general race conditions.

This is mathematically impossible in situations where you do not control the scheduler, which is true for the normal OS environment.”

66
FishFacereply
piefed.social

It is, in large part. The rules on ownership and borrowing mean that it is not supposed to be possible to change memory that something else can be concurrently reading from. That means you are forced to obtain references through protective mechanisms, which should protect from race conditions.

All of that can go out of the window if you use unsafe.

4
MotoAshreply
piefed.social

Note how the ticket cited is in an unsafe block, because it uses the OS scheduler, not its own. It is not Rust's fault.

6

Rust doesn't have a scheduler.
The issue is the false assumption, that the remove operation can safely be done without taking a lock. This can be done in some specific data structures using atomic operations, but here the solution was to just take the lock. The same thing could have happened in a C code base but without the unsafe block indicating where to look for the bug.

4

Yeah, I'm not saying it's rust's fault. Restricting this to unsafe makes it a lot easier to reason about where such problems can occur.

I just don't think anyone should give the impression that rust's memory safety is not about race conditions.

3

Bad code is bad code. We'll see more of this as rust is implemented into core software.

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