[neerajsi]

I've worked in and around srwlock for a long time. I don't think it's all that reasonable to think you should get "shared starve exclusive" by default, which is what you're asking for. We used to demand that kind of behavior in some windows filesystem code and it's always been a design mistake.

[LegionMammal978]

I don't think SharedStarveExclusive is what GP is talking about? From the description, it sounds like currently, a shared acquire immediately after an exclusive release will get silently 'upgraded' to an exclusive acquire in some cases (and remain exclusive until released), which can easily cause issues. And it can't even be detected or worked around, since the SRWLock functions don't return any information about the status of the lock.

It looks like the Rust standard library migrated away from SRWLOCK on account of this issue [0].

[0] https://github.com/rust-lang/rust/issues/121949

[tialaramex]

Yeah, as that Rust issue states, this was first replicated by a C++ programmer and STL (the person, not the Microsoft name for the C++ stdlib) said it looks like a bug in SRWLock.

There's a Microsoft internal ticket which I can't read (but STL can because he's a Microsoft employee) but there's also a GitHub issue for STL (this time the stdlib, a GitHub project, although it was opened by the person) https://github.com/microsoft/STL/issues/4448 and it's confirmed in that issue this is a bug in SRWLock, thus no work for STL† (either the project or the person).

It's not unusual (especially in C++ but this happens anywhere) that people would rather contort themselves to believe crazy things than accept that it's just a bug.

† Both Windows and C++ holds themselves to a very low standard, "Yeah, it's broken, too bad" is acceptable. Once you've determined that it's a bug you're done.

[neerajsi]

Wow, thanks for the links. I was previously unaware of this issue. I checked the referenced bug and I see that it is fixed and will be released in an upcoming version of Windows.