I've noticed this in this version and some previous snapshots, a player will be online then get timed out. After that they will still appear to be online from the server selection screen. No players are able to login to the server until it is restarted, which seems to take longer after this has happened.

The world I'm playing on is about a year old and we've progressed through most stable snapshots. It doesn't happen too often but is irritating when I'm not around to restart the server.

Log showing us trying to login and the time between my last login (about 30 seconds before I restarted the server) and the server actually starting to restart.

14:43:03 [Info] UUID of player LeanneLollipop is 1da3f925-5d5b-4c51-b9c5-c97ec1c75a99
14:43:45 [Info] UUID of player LeanneLollipop is 1da3f925-5d5b-4c51-b9c5-c97ec1c75a99
14:44:29 [Info] UUID of player LeanneLollipop is 1da3f925-5d5b-4c51-b9c5-c97ec1c75a99
14:45:08 [Info] UUID of player LeanneLollipop is 1da3f925-5d5b-4c51-b9c5-c97ec1c75a99
14:50:58 [Info] UUID of player LeanneLollipop is 1da3f925-5d5b-4c51-b9c5-c97ec1c75a99
14:51:00 [Info] UUID of player LeanneLollipop is 1da3f925-5d5b-4c51-b9c5-c97ec1c75a99
15:02:28 [Info] UUID of player LeanneLollipop is 1da3f925-5d5b-4c51-b9c5-c97ec1c75a99
15:02:49 [Info] UUID of player LeanneLollipop is 1da3f925-5d5b-4c51-b9c5-c97ec1c75a99
15:03:09 [Info] UUID of player LeanneLollipop is 1da3f925-5d5b-4c51-b9c5-c97ec1c75a99
15:03:30 [Info] UUID of player LeanneLollipop is 1da3f925-5d5b-4c51-b9c5-c97ec1c75a99
15:24:10 [Info] UUID of player DecrepitDoors is f77e0ee0-b39a-4749-b16e-020167bca340
15:24:43 [Info] UUID of player DecrepitDoors is f77e0ee0-b39a-4749-b16e-020167bca340
15:31:27 [Info] Starting minecraft server version 15w42a