public ClientStats getClientStats() { Map<String, Long> totalConnectionsPerHost = openChannels.stream().map(Channel::remoteAddress).filter(a -> a.getClass() == InetSocketAddress.class) .map(a -> (InetSocketAddress) a).map(InetSocketAddress::getHostName).collect(Collectors.groupingBy(Function.identity(), Collectors.counting())); Map<String, Long> idleConnectionsPerHost = channelPool.getIdleChannelCountPerHost(); Map<String, HostStats> statsPerHost = totalConnectionsPerHost.entrySet().stream().collect(Collectors.toMap(Entry::getKey, entry -> { final long totalConnectionCount = entry.getValue(); final long idleConnectionCount = idleConnectionsPerHost.getOrDefault(entry.getKey(), 0L); final long activeConnectionCount = totalConnectionCount - idleConnectionCount; return new HostStats(activeConnectionCount, idleConnectionCount); })); return new ClientStats(statsPerHost); }