Lost connection detection is sensitive to changes in system time

[ItsHarper]

Because Lost Connection Detection uses the java.util.Timer API instead of the ScheduledThreadPoolExecutor API, it is sensitive to changes in the system time. For example, if you set the system time to a point years in the future, the connectionLostTimerTask will be called constantly, frequently causing disconnects as the clients cannot respond before the task is called again. This is particularly an issue for embedded devices that must have their clock set at runtime.

The best solution would seem to be to use the ScheduledThreadPoolExecutor API. I plan to submit a PR.

To Reproduce

1. Start a WebSocket server using this library
2. Set the system time to a few years in the future

[marci4]

Hey @noahAndrews,

how can we solve the problem of the last pong received.

I used System.currentTimeMillis() for detecting a missing response.

See https://github.com/TooTallNate/Java-WebSocket/blob/master/src/main/java/org/java_websocket/WebSocketImpl.java#L804

Best regards,
Marcel

[ItsHarper]

@marci4 I just updated PR #878 to fix that.

[ItsHarper]

Speaking of lost connection detection, I just made this modification to the wiki: https://github.com/TooTallNate/Java-WebSocket/wiki/Lost-connection-detection/_compare/de53ff89cd759a2517cdb36199ce4daf78dbdbe9...4d3b2372b9907c77a23a93f7cf8f132c0fba0537

Let me know if you don't like anything I changed.

[marci4]

Looks good!