swoole server下使用了swoole_event_add，在关闭服务的时候日志中出现了提示
swWorker_reactor_is_empty (ERRNO 9012): worker exit timeout, forced to terminate
并且关闭服务时间比正常情况下要慢。
解决方法
开启 'reload_async' => true 配置
注册onWorderExit回调，在回调中删除事件
public function onWorkerExit(Server $server, int $worker_id)
{
Timer::clearAll();
swoole_event_del($this->process->pipe);
}
问题解决
swoole版本4.4.5，php7.2.19
swoole
Swoole => enabled
Author => Swoole Team
Version => 4.4.5
Built => Sep 9 2019 11:08:20
coroutine => enabled
epoll => enabled
eventfd => enabled
signalfd => enabled
cpu_affinity => enabled
spinlock => enabled
rwlock => enabled
sockets => enabled
openssl => OpenSSL 1.0.2k-fips 26 Jan 2017
http2 => enabled
pcre => enabled
zlib => enabled
mutex_timedlock => enabled
pthread_barrier => enabled
futex => enabled
mysqlnd => enabled
async_redis => enabled
Directive => Local Value => Master Value
swoole.enable_coroutine => On => On
swoole.enable_library => On => On
swoole.enable_preemptive_scheduler => Off => Off
swoole.display_errors => On => On
swoole.use_shortname => On => On
swoole.unixsock_buffer_size => 8388608 => 8388608
)
