- Kubelet TCP and HTTP probes are now more effective using networking resources:
  conntrack entries, sockets. This is achieved by reducing the `TIME-WAIT` state
  of the connection to 1 second, instead of the defaults 60 seconds. This allows
  kubelet to free the socket, and free conntrack entry and ephemeral port associated. ([#115143](https://github.com/kubernetes/kubernetes/pull/115143), [@aojea](https://github.com/aojea))

- Kube-proxy: delete stale conntrack UDP entries for loadbalancer ingress IP. ([#104151](https://github.com/kubernetes/kubernetes/pull/104151), [@aojea](https://github.com/aojea)) [SIG Network]

- Fixes a regression introduced in 1.29 where conntrack entries for UDP connections
  to deleted pods did not get cleaned up correctly, which could (among other things)

- During initialization phase (preflight), kubeadm now verifies the presence of the conntrack executable ([#85857](https://github.com/kubernetes/kubernetes/pull/85857), [@hnanni](https://github.com/hnanni)) [SIG Cluster Lifecycle]

* Tune down initialDelaySeconds for readinessProbe. ([#33146](https://github.com/kubernetes/kubernetes/pull/33146), [@MrHohn](https://github.com/MrHohn))
* kube-proxy: Add a lower-bound for conntrack (128k default) ([#33051](https://github.com/kubernetes/kubernetes/pull/33051), [@thockin](https://github.com/thockin))

*   Added iptables rules to allow Pod traffic even when default iptables policy is to reject. ([#52569](https://github.com/kubernetes/kubernetes/pull/52569),[ @tmjd](https://github.com/tmjd))
*   You can once again use 0 values for conntrack min, max, max per core, tcp close wait timeout, and tcp established timeout; this functionality was broken in 1.8. ([#55261](https://github.com/kubernetes/kubernetes/pull/55261),[ @ncdc](https://github.com/ncdc))

#### **CoreDNS**

- Adds additional testing to ensure that udp pods conntrack are cleaned up ([#90180](https://github.com/kubernetes/kubernetes/pull/90180), [@JacobTanenbaum](https://github.com/JacobTanenbaum)) [SIG Architecture, Network and Testing]

    contract { callsInPlace(action, InvocationKind.EXACTLY_ONCE) }
    return lock.withLock(action)
  }

  inline fun <T> RealCall.withLock(action: () -> T): T {
    contract { callsInPlace(action, InvocationKind.EXACTLY_ONCE) }
    return lock.withLock(action)
  }

  inline fun <T> Http2Connection.withLock(action: () -> T): T {
    contract { callsInPlace(action, InvocationKind.EXACTLY_ONCE) }

import java.util.Iterator;
import java.util.Map.Entry;
import java.util.SortedMap;

/**
 * Tests representing the contract of {@link SortedMap}. Concrete subclasses of this base class test
 * conformance of concrete {@link SortedMap} subclasses to that contract.
 *
 * @author Jared Levy
 */
// TODO: Use this class to test classes besides ImmutableSortedMap.
@GwtCompatible

   * documentation.
   */
  public void add(Runnable runnable, Executor executor) {
    // Fail fast on a null. We throw NPE here because the contract of Executor states that it throws
    // NPE on null listener, so we propagate that contract up into the add method as well.
    checkNotNull(runnable, "Runnable was null.");
    checkNotNull(executor, "Executor was null.");