Port bind skipped at server startup

[wtlucy]

Describe the bug
In an extremely rare scenario, configured ports can silently fail to bind - preventing Liberty from using them. This issue is caused by a subtle race condition in the code responsible for delaying the port bind until the server is ready to handle traffic.

In the failing scenario, the port started message will not be emitted - for example the following message will be missing:

CWWKO0219I: TCP Channel defaultHttpEndpoint has been started and is now listening for requests on host *  (IPv4) port 9080.

and the following FFDC will be seen:

Exception = java.lang.RuntimeException
Source = com.ibm.ws.tcpchannel.internal.NBAcceptChannelSelector
probeid = 254
Stack Dump = java.lang.RuntimeException: java.nio.channels.NotYetBoundException
	at com.ibm.ws.tcpchannel.internal.NBAcceptChannelSelector.performRequest(NBAcceptChannelSelector.java:358)
	at com.ibm.ws.tcpchannel.internal.ChannelSelector.run(ChannelSelector.java:257)
	at java.base/java.lang.Thread.run(Thread.java:866)
Caused by: java.nio.channels.NotYetBoundException
	at java.base/sun.nio.ch.ServerSocketChannelImpl.begin(ServerSocketChannelImpl.java:246)
	at java.base/sun.nio.ch.ServerSocketChannelImpl.accept(ServerSocketChannelImpl.java:283)
	at com.ibm.ws.tcpchannel.internal.NBAcceptChannelSelector.performRequest(NBAcceptChannelSelector.java:278)
	... 2 more

Steps to Reproduce
Configure one or more ports to start, for example:

    <httpEndpoint id="defaultHttpEndpoint"
                  host="*"
                  httpPort="9080"
                  httpsPort="9443">
    </httpEndpoint>   

And start the server. In this scenario, one or more of the ports will silently fail to bind.

Expected behavior
All configured ports should start, or if there is a problem some meaningful error message should be logged.

Diagnostic information:

• OpenLiberty Version: All
• Affected feature(s) All
• Java Version: reported on IBM Semeru Runtime Open Edition (11.0.12+7)
• server.xml configuration: N/A, just need multiple ports