ADDITIONAL SYSTEM INFORMATION :
System:
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=20.04
DISTRIB_CODENAME=focal
DISTRIB_DESCRIPTION="Ubuntu 20.04.6 LTS"
Java :
openjdk version "21" 2023-09-19 LTS
OpenJDK Runtime Environment Temurin-21+35 (build 21+35-LTS)
OpenJDK 64-Bit Server VM Temurin-21+35 (build 21+35-LTS, mixed mode, sharing)

A DESCRIPTION OF THE PROBLEM :
SockServerSelector" Id=42 WAITING on java.util.concurrent.locks.ReentrantLock$NonfairSync@32dfbac0
    at java.base@21/jdk.internal.misc.Unsafe.park(Native Method)
    - waiting on java.util.concurrent.locks.ReentrantLock$NonfairSync@32dfbac0
    at java.base@21/java.util.concurrent.locks.LockSupport.park(LockSupport.java:221)
    at java.base@21/java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:754)
    at java.base@21/java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:990)
    at java.base@21/java.util.concurrent.locks.ReentrantLock$Sync.lock(ReentrantLock.java:153)
    at java.base@21/java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:322)
    at java.base@21/sun.nio.ch.SocketChannelImpl.implCloseNonBlockingMode(SocketChannelImpl.java:1093)
    at java.base@21/sun.nio.ch.SocketChannelImpl.implCloseSelectableChannel(SocketChannelImpl.java:1124)
    at java.base@21/java.nio.channels.spi.AbstractSelectableChannel.implCloseChannel(AbstractSelectableChannel.java:258)
    at at java.base@21/jdk.internal.misc.Unsafe.park(Native Method)
    - waiting on java.util.concurrent.locks.ReentrantLock$NonfairSync@32dfbac0
    at java.base@21/java.util.concurrent.locks.LockSupport.park(LockSupport.java:221)
    at java.base@21/java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:754)
    at java.base@21/java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:990)
    at java.base@21/java.util.concurrent.locks.ReentrantLock$Sync.lock(ReentrantLock.java:153)
    at java.base@21/java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:322)
    at java.base@21/sun.nio.ch.SocketChannelImpl.implCloseNonBlockingMode(SocketChannelImpl.java:1093)
    at java.base@21/sun.nio.ch.SocketChannelImpl.implCloseSelectableChannel(SocketChannelImpl.java:1124)
    at java.base@21/java.nio.channels.spi.AbstractSelectableChannel.implCloseChannel(AbstractSelectableChannel.java:258)
    at java.base@21/java.nio.channels.spi.AbstractInterruptibleChannel.close(AbstractInterruptibleChannel.java:113)
    at com.xxxxxx._channelClose(Unknown Source)
     ...
    at java.base@21/sun.nio.ch.SelectorImpl.processReadyEvents(SelectorImpl.java:297)
    at java.base@21/sun.nio.ch.EPollSelectorImpl.processEvents(EPollSelectorImpl.java:201)
    at java.base@21/sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:141)
    at java.base@21/sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:130)
    at java.base@21/sun.nio.ch.SelectorImpl.select(SelectorImpl.java:162)
    at com.xxx
....
    at java.base@21/java.lang.Thread.runWith(Thread.java:1596)
    at java.base@21/java.lang.Thread.run(Thread.java:1583)