Issue #16476 has been updated by mame (Yusuke Endoh). Status changed from Open to Closed #19965 solved the problem, so I'll close it. I completely forgot this ticket, but the concept (pthread_create on every call to getaddrinfo(3)) was the same as in #19965. Just for case, #19965 is a bit more elaborate: * It works as before in environments where pthread is not available. * It includes the same hack for not only `getaddrinfo(3)` but also `getnameinfo(3)`. * `pthread_cancel` is not used because until recently [there was a bug in glibc](https://bugzilla.redhat.com/show_bug.cgi?id=1405071) where `pthread_cancel` of a pthread that is calling `getaddrinfo(3)` would cause subsequent name resolution to stick: * It attempts to use `pthread_setaffinity_np` to reduce speed degradation. ---------------------------------------- Feature #16476: Socket.getaddrinfo cannot be interrupted by Timeout.timeout https://bugs.ruby-lang.org/issues/16476#change-105143 * Author: kirs (Kir Shatrov) * Status: Closed * Priority: Normal * Assignee: Glass_saga (Masaki Matsushita) ---------------------------------------- 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. -- https://bugs.ruby-lang.org/