Socket.getaddrinfo cannot be interrupted by Timeout.timeout
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
While https://bugs.ruby-lang.org/issues/15553 improves the situation for
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
Addrinfo.getaddrinfo("www.ruby-lang.org", "http", timeout: 10) calls
getaddrinfo_a, which is interruptible:
# 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.