Getting Started

This guide explains how to use io-event for non-blocking IO.

v1.19.4

• Capture errno immediately after epoll_wait / kevent, preventing stale or subsequently clobbered values from raising a spurious Errno::* when a native selector wait is interrupted or skipped.

v1.19.3

• Prevent URing, EPoll, and KQueue from entering a native wait when a signal exception becomes pending during the GVL transition. On Ruby versions without RB_NOGVL_PENDING_INTR_FAIL, the fallback now refreshes pending-interrupt state immediately before releasing the GVL while preserving the caller's exception-delivery timing.

v1.19.2

• Use rb_process_status_for when available to construct URing process_wait results directly from waitid, avoiding the extra reap syscall previously needed to build a Process::Status.

v1.19.1

• Fix Process.waitall / Process.detach under the URing selector: when io_uring's waitid reported an error (e.g. ECHILD when there are no more children), the process_wait hook raised instead of returning the error as a Process::Status, so callers that expect waitpid to report "no more children" rather than raise would fail.

v1.19.0

• Use io_uring_prep_waitid for process_wait in the URing selector (Linux 6.7+), waiting for child exit directly in the ring instead of polling on a pidfd. The child is reaped via rb_process_status_wait (using WEXITED | WNOWAIT) to construct a correct Process::Status, and process_wait(-1, ...) / process_wait(0, ...) are now supported.
• Support waiting for any child or a process group (pid <= 0) on all selectors. The EPoll (pidfd_open) and KQueue (EVFILT_PROC) selectors can only watch a specific process, so these cases now fall back to a blocking wait on a dedicated thread; joining it is fiber-scheduler aware, so the reactor keeps running.

v1.18.0

• Fixed: Avoid entering a blocking native selector wait when an interrupt is already pending for the current thread.

v1.17.0

• Report inherited selector objects as closed after fork, and avoid closing descriptors they no longer own.

v1.16.4

• Correctly implement Interrupt#signal so that it is robust enough to be called by Scheduler#unblock.

v1.16.3

• Handle IOError raised while shutting down the pure Ruby interrupt pipe, so IO::Event::Interrupt#close does not leak expected shutdown errors from the interrupt fiber.

v1.16.2

• Improve timer heap performance by batching scheduled timer insertion, compacting cancelled timers during flush, and avoiding unnecessary heap rebuilds for small incremental inserts.