Netty is not shutting down cleanly after EtcdClient.close is called about etcd4j HOT 3 CLOSED

Seeing the same issue where the client closes but the process doesn't end because there's still a non-daemon thread hanging around, I believe line 18 in RetryPolicy is the culprit:

private static final HashedWheelTimer timer = new HashedWheelTimer();

Per the Netty documentation even though start was never explicitly called, stop() should be called on the timer object to clean up all the resources including this thread pool (from my jstack trace):

"pool-1-thread-1" #12 prio=0 os_prio=0 tid=0x0000 nid=0x0000 waiting on condition [0x0000]
   java.lang.Thread.State: TIMED_WAITING (sleeping)
    at java.lang.Thread.sleep(Native Method)
    at io.netty.util.HashedWheelTimer$Worker.waitForNextTick(HashedWheelTimer.java:461)
    at io.netty.util.HashedWheelTimer$Worker.run(HashedWheelTimer.java:360)
    at java.lang.Thread.run(Thread.java:745)

from etcd4j.

Thanks for the reporting in! I did not close HashedWheelTimer because it can be used by multiple etcd clients. It is advised to only have one in a App.
I now catch retried calls so they are canceled if they are still open if event loop is closed.

from etcd4j.

It is fixed in the 2.8 release.

from etcd4j.