Mac need long time to exit when connect RC1 testnet.

[superboyiii]

Mac need long time to exit when connecting RC1 testnet.

1. Download RC1 Mac version: https://github.com/neo-project/neo-node/releases/download/v3.0.0-rc1/neo-cli-osx-x64.zip
2. Run it, wait for several seconds to ensure it has synced some height.
3. Input exit. (ctrl + c has the same effect)

Seems akka not disconnect at once but just wait. It can take about 3 minutes to exit in Mac. I haven't seen this issue on other OS like (win10, centOS7.6, unbuntu 16.04). @erikzhang @shargon

[shargon]

This only happens with RC1?

[shargon]

Old, if remains, please re-open