[ruby-core:101754] [Ruby master Feature#16476] Socket.getaddrinfo cannot be interrupted by Timeout.timeout

Issue #16476 has been updated by Dan0042 (Daniel DeLorme).


naruse (Yui NARUSE) wrote in #note-15:
> It's a long requested series of improvements for HTTP client like read_timeout, connect_timeout, and write_timeout.
> resolv_timeout is the last piece of that.

How common is it to need separate timeouts for all of these? I can easily imagine the resolv_timeout as being part of the connect_timeout (i.e. resolv+connect may not exceed connect_timeout). And at least in my experience I'll want a single "general timeout" for resolv+connect+write+read. For that reason I _really_ like Jeremy's suggestion of a single `deadline` argument. You can even have a single deadline for multiple http requests. This is really perfect for most uses cases that I'm familiar with.

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Feature #16476: Socket.getaddrinfo cannot be interrupted by Timeout.timeout
https://bugs.ruby-lang.org/issues/16476#change-89581

* Author: kirs (Kir Shatrov)
* Status: Open
* Priority: Normal
* Assignee: Glass_saga (Masaki Matsushita)
* Target version: 3.1
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It seems like the blocking syscall done by `Socket.getaddrinfo` blocks Ruby VM in a way that Timeout.timeout has no effect.
See reproduction steps in getaddrinfo_interrupt.rb (https://gist.github.com/kirs/00c02ef92e0418578135fe0a6cbd3d7d). This affects all modern Ruby versions, including the latest 2.7.0.

Combined with default 10s resolv timeout on many Linux systems, this can have a very noticeable effect on production Ruby apps being not resilient to slow DNS resolutions, and being unable to fail fast even with `Timeout.timeout`.

While https://bugs.ruby-lang.org/issues/15553 improves the situation for `Addrinfo.getaddrinfo`, `Socket.getaddrinfo` is still blocking the VM and Timeout has no effect.

I'd like to discuss what could be done to make that call non-blocking for threads in Ruby VM.

**UPD:** looking closer, I can see that `Socket.getaddrinfo("www.ruby-lang.org", "http")` and `Addrinfo.getaddrinfo("www.ruby-lang.org", "http")` call non-interruptible `getaddrinfo`, while `Addrinfo.getaddrinfo("www.ruby-lang.org", "http", timeout: 10)` calls `getaddrinfo_a`, which is interruptible:

``` ruby
# interrupts as expected
Timeout.timeout(1) do
  Addrinfo.getaddrinfo("www.ruby-lang.org", "http", timeout: 10)
end
```

I'd maybe suggest that we try to *always* use `getaddrinfo_a` when it's available, including in `Socket.getaddrinfo`. What downsides that would have?
I'd be happy to work on a patch.



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