@Override
    public void channelInactive(ChannelHandlerContext ctx) {
      log.trace("Connection {} become inactive.", ctx.channel());
      closeAndReleaseParent(ctx, new ClosedChannelException());
    }
Netty calls this function when channel becomes inactive. The channel becomes inactive AFTER it is closed (either by
the local or the remote end). One case is when server shutdown.
ambry-network/src/main/java/com/github/ambry/network/http2/Http2MultiplexedChannelPool.java