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Async/Await is finally back in Zig

(charlesfonseca.substack.com)
39 points barddoo | 2 comments | | HN request time: 0.001s | source
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ajross ◴[] No.45782414[source]
Is it time now to say that async was a mistake, a-la C++ exceptions? The recent futurelock discussion[1] more or less solidified for me that this is all just a mess. Not just that one bug, but the coloring issue mentioned in the blog post (basically async "infects" project code requiring that you end up porting or duplicating almost everything -- this is especially true in Python). The general cognitive load of debugging inside out code is likewise really high, even if the top-level expression of the loop generator or whatever is clean.

And it's all for, what? A little memory for thread stacks (most of which ends up being a wash because of all the async contexts being tossed around anyway -- those are still stacks and still big!)? Some top-end performance for people chasing C10k numbers in a world that has scaled into datacenters for a decade anyway?

Not worth it. IMHO it's time to put this to bed.

[1] No one in that thread or post has a good summary, but it's "Rust futures consume wakeup events from fair locks that only emit one event, so can deadlock if they aren't currently being selected and will end up waiting for some other event before doing so."

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amelius ◴[] No.45782432[source]
What is wrong about C++ exceptions?
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1. jandrewrogers ◴[] No.45782723[source]
There are cases in systems-y code where it is not safe to unwind the stack in the ordinary way and it is difficult to contain the side-effects. These can be non-obvious and subtle edge cases that are often difficult to see and tricky to handle correctly. C++ today is primarily used in code contexts where these kinds of issues can occur. This is why it is a standard practice to disable exceptions at build time i.e. -fno-exceptions.

With the benefit of hindsight, explicit handling and unwinding has proven to be safer and more reliable.

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2. amelius ◴[] No.45782951[source]
But you can implement exceptions by using the same IF statement approach you would use for manual error handling. No need for unwinding tables and such if that optimization is a bridge too far for your specific target platform.