[knx2] reading values does not work any more

[Alex5719]

Hello,

I am running a snapshot build of OpenHAB 2.5 with the knx2 binding accessing two different KNX IP Interfaces in TUNNEL mode. Therefor I have configured two separate KNX Bridges in my things file. My Configuration was running well till build 1607. The later builds showed the strange behaviour that KNX read requests did not work randomly on one or the other bridge.

I first thought the strange behaviour is due to the running refactorings but I now installed the new milestone 2 build of OH 2.5 and I still get the described strange behaviour.

I get the following exception in my log (2.5 Milestone 2 Build):

2019-08-11 16:25:26.600 [WARN ] [mmon.WrappedScheduledExecutorService] - Scheduled runnable ended with an exception: java.lang.NullPointerException: null at org.openhab.binding.knx.internal.client.AbstractKNXClient.readNextQueuedDatapoint(AbstractKNXClient.java:283) ~[?:?] at org.openhab.binding.knx.internal.client.AbstractKNXClient.lambda$1(AbstractKNXClient.java:199) ~[?:?] at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:51 1) ~[?:?] at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308) ~[?: ?] at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask. access$301(ScheduledThreadPoolExecutor.java:180) ~[?:?] at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask. run(ScheduledThreadPoolExecutor.java:294) ~[?:?] at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor. java:1149) [?:?] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor .java:624) [?:?] at java.lang.Thread.run(Thread.java:748) [?:?]

Expected Behavior

Current Behavior

Possible Solution

Steps to Reproduce (for Bugs)

1. 2.

Context

Your Environment

• Version used: (e.g., openhab and addon versions)
• Environment name and version (e.g. Chrome 39, node.js 5.4, Java 8, ...):
• Operating System and version (desktop or mobile, Windows 10, Raspbian Jessie, ...):

[nanosonde]

I am also experiencing the same issue here with the same error messages in openhab.log. I am also using KNX in tunnel mode with a certified KNX Gateway from MDT. In 2.5.0 M1 this was running flawlessly.

Seems to be related to these changes: https://github.com/openhab/openhab2-addons/pull/5695/

[Alex5719]

I am also using MDT devices.

[nanosonde]

There used to be the following NULL check before it was removed here.

However, from [here](https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/LinkedBlockingQueue.html#poll()) I can see that poll() returns NULL if the queue is empty. So the check should still be there in this case.

[kaikreuzer]

@J-N-K as you worked on https://github.com/openhab/openhab2-addons/pull/5695, which was the only change: Can you reproduce this issue and would have an idea how to fix it?

[J-N-K]

My fault. Will provide a fix ASAP.

[Alex5719]

I have installed snapshot build 2.5.0~S1663-1 and can confirm that the bug is fixed.

Thank you for your great work on openHAB.