Technically torn reads can succeed

[mtak-]

This is a ridiculous corner case.

Thread 1:
Starts a read, getting a sequence number, and reads some of the data.

Other threads:
Successfully perform exactly 2^(mem::size_of::<usize>() - 1) writes, leaving the sequence number effectively unchanged.

Thread 1:
Finishes reading the data, and sees the sequence number unchanged. It then returns the torn read.

On 64-bit machines, this would take a few lifetimes to occur, on 32-bit machines it might require the reader thread to be inactive for around one second.

[Amanieu]

Yes, this is a known issue with seqlock. However the probability of hitting this is so low that it may as well be non-existent.

[mtak-]

That makes sense. Thanks for checking this out. I'll go ahead and close this issue.