IssueTracker

After the "adb wait-for-device" command is killed, the thread created in adb server doesn't exit and keep it there to monitor device. If keep doing this(like a automation test tool), hundreds of threads will be crated and make adb server crash with running out of resource.

Steps to reproduce the problem.
- run "adb -s xxxxx wait-for-device"
- use "pstree -p <pid-of-adb-server>" to check count of threads
- kill it by ctrl+C.
- use pstree check threads info.


Another issues, adb server suddenly restart can cause device offline due to protocol get miss-match. so this is a big problem for adb.