[samuel-williams-shopify]

Summary

• improve pure Ruby selector compatibility with JRuby by avoiding unsupported IO::Buffer operations and using nonblocking Ruby IO methods where needed
• make Selector.nonblock restore nonblocking state explicitly and ensure the helper is loaded for the pure Ruby selector
• add targeted JRuby skips for VM/platform gaps around nested fiber transfer, closed-IO scheduling, FIFO channels, TCP OOB priority readiness, and UNIXSocket buffer sizing
• keep the branch based directly on main, without the old fork diagnostic workflow/test commits

Verification

• bundle exec rubocop
• bundle exec bake test

Note: this replaces the old interrupt-fix PR branch.

[samuel-williams-shopify]

cc @headius

[headius]

I'll jump in to help where I can!

[ioquatix]

@headius I filed a few upstream bug reports on JRuby.

IO::Buffer is not set in stone yet, but IO::Buffer#read and #write may not follow the current spec which is making things more tricky than it should be.

Also, what's the current state of Loom/io_uring etc? Just wondering if it would make sense to create a JNI for better IO. How crazy would that be?

[sampokuokkanen]

@ioquatix @headius
A status update!

I ran io-event main against current JRuby master, and most of the JRuby skips here aren't needed anymore. These pass now:

• #wakeup from a different thread (both)
• exception raised during wait from another fiber on the same IO
• closed_io (both)
• interruptable
• nonblock.rb nonblock? check
• queue "can yield from resumed fiber"

The IO::Buffer#read/#write fallback isn't needed either: JRuby has both, and the suite passes with the library as it is on main.

Fixes in progress:

• FIFO select: Select on FIFOs and devices with their own jnr-enxio selector jruby/jruby#9918
• UNIXSocket SO_SNDBUF/SO_RCVBUF (write_deadlock): Support buffer size and keepalive socket options on UNIX sockets jruby/jruby#9920
• rlimit_core spawn option: JRuby doesn't support it, so Skip the core dump process wait test on JRuby. #238 skips that test on JRuby

Still needed:

• OOB priority: Java NIO has no priority readiness, so that skip stays. This probably needs a skip on io-event. Skipped by Skip the priority event test on JRuby. #239.
• interrupt.rb fork: JRuby defines a Process.fork stub, so skip_unless_method_defined doesn't catch it. (wait... this is a bug in JRuby.) Fixed by Treat not-implemented methods as undefined in method_defined? and defined? jruby/jruby#9929

With those in, the only JRuby failure left on macOS is the "read and write from two different fibers" test. That's a kqueue selector bug in jnr-enxio (jnr/jnr-enxio#50), and the test passes on Linux.

[headius]

Very exciting progress!

[headius]

FYI the jnr-enxio fix is merged and will be released and incorporated into 10.0.8.0 and 10.1.3.0 coming this week or early next.