Releases

v0.27.5

• Make the child handling more robust in the face of exceptions.

v0.27.4

• Fix race condition where wait_for could modify @running while it was being iterated over (each_value) during health checks.

v0.27.3

• Add log for starting child, including container statistics.
• Don't try to (log) "terminate 0 child processes" if there are none.

v0.27.2

• More logging, especially around failure cases.

v0.27.1

• Log caller and timeout when waiting on a child instance to exit, if it blocks.

v0.27.0

• Increased default interrupt timeout and terminate timeout to 10 seconds each.
• Expose ASYNC_CONTAINER_INTERRUPT_TIMEOUT and ASYNC_CONTAINER_TERMINATE_TIMEOUT environment variables for configuring default timeouts.

v0.26.0

Production Reliability Improvements

This release significantly improves container reliability by eliminating production hangs caused by unresponsive child processes.

SIGKILL Fallback Support: Containers now automatically escalate to SIGKILL when child processes ignore SIGINT and SIGTERM signals. This prevents the critical production issue where containers would hang indefinitely waiting for uncooperative processes to exit.

Hang Prevention: Individual child processes now have timeout-based hang prevention. If a process closes its notification pipe but doesn't actually exit, the container will detect this and escalate to SIGKILL after a reasonable timeout instead of hanging forever.

Improved Three-Phase Shutdown: The Group#stop() method now uses a cleaner interrupt → terminate → kill escalation sequence with configurable timeouts for each phase, giving well-behaved processes multiple opportunities to shut down gracefully while ensuring unresponsive processes are eventually terminated.

v0.25.0

• Introduce async:container:notify:log:ready? task for detecting process readiness.

v0.24.0

• Add support for health check failure metrics.

v0.23.0

Add support for NOTIFY_LOG for Kubernetes readiness probes.

You may specify a NOTIFY_LOG environment variable to enable readiness logging to a log file. This can be used for Kubernetes readiness probes, e.g.

containers:
	- name: falcon
		env:
			- name: NOTIFY_LOG
				value: "/tmp/notify.log"
		command: ["falcon", "host"]
		readinessProbe:
			exec:
				command: ["sh", "-c", "grep -q '\"ready\":true' /tmp/notify.log"]
			initialDelaySeconds: 5
			periodSeconds: 5
			failureThreshold: 12

v0.21.0

• Use SIGKILL/Thread#kill when the health check fails. In some cases, SIGTERM may not be sufficient to terminate a process because the signal can be ignored or the process may be in an uninterruptible state.

v0.20.1

• Fix compatibility between class Async::Container::Hybrid and the health check.
• Async::Container::Generic#initialize passes unused arguments through to class Async::Container::Group.

v0.20.0

• Improve container signal handling reliability by using Thread.handle_interrupt except at known safe points.
• Improved logging when child process fails and container startup.

Add health_check_timeout for detecting hung processes.

In order to detect hung processes, a health_check_timeout can be specified when spawning children workers. If the health check does not complete within the specified timeout, the child process is killed.

require "async/container"

container = Async::Container.new

container.run(count: 1, restart: true, health_check_timeout: 1) do |instance|
	while true
		# This example will fail sometimes:
		sleep(0.5 + rand)
		instance.ready!
	end
end

container.wait

If the health check does not complete within the specified timeout, the child process is killed:

 3.01s     warn: Async::Container::Forked [oid=0x1340] [ec=0x1348] [pid=27100] [2025-02-20 13:24:55 +1300]
               | Child failed health check!
               | {
               |   "child": {
               |     "name": "Unnamed",
               |     "pid": 27101,
               |     "status": null
               |   },
               |   "age": 1.0612829999881797,
               |   "health_check_timeout": 1
               | }