KemaFork.cr

require "kemal"
require "logger"

log = Logger.new(STDERR)
log.level = Logger::DEBUG

get "/" do
  "Hello World! I am a process with pid #{Process.pid}"
end

children_procs = [] of Process
16.times do
    unless (child_p = Process.fork) # if we are forked child - run Kemal
        log.info("I am a child process with pid #{Process.pid}")
        Signal::TERM.trap do
            log.warn("Process #{Process.pid} received TERM signal, so we have to emergency cleanup and exit now")
            Kemal.stop
            exit(0)
        end
        Kemal.run { |cfg| cfg.server.not_nil!.bind(reuse_port: true) }
        log.error("[#{Process.pid}] Ooops. How is that possible?")
        exit(1)
    else
        children_procs << child_p
    end
end

Signal::HUP.trap do
    log.info("HUP received by master process #{Process.pid}. We have to terminate our children (by pid): [" + children_procs.map {|p| p.pid}.join(", ") + "]")

    children_procs.each do |child_p|
        unless child_p.terminated?
            child_pid = child_p.pid
            log.debug("Sending signal TERM (15) to process #{child_pid}")
            child_p.kill
            unless child_p.terminated?
                spawn do
                    count = 0
                    until child_p.terminated? || (count += 1) >= 200
                        sleep 0.01
                        child_p.kill
                    end
                    unless child_p.terminated?
                        log.error("Can't terminate child process ##{child_pid} for some unknown reason")
                    end
                end
                child_p.wait
            end
        else
            log.warn("Strange, but child process #{child_p.pid} seems to be already dead")
        end
        log.warn("Child ##{child_pid} was normaly terminated")
    end
end
log.info("I am a main process with pid #{Process.pid}. Send me HUP signal to terminate Kemal server gracefully")
children_procs.each { |child_p| child_p.terminated? || child_p.wait }