CODEWITHSUNDEEP
javanetty
alobodzk
alobodzk

Reputation: 1334

How to track exact number of open connections in netty server

I have a question about netty server monitoring. I want to see how many open connections to the server are there, so to do that we have a code that has an atomic integer counter that is increased by 1 on ChannelInitializer.initChannel(..) method and decremented by 1 in closeFuture listener for that SocketChannel channel. For some reason that I can't figure out, it doesn't go to zero and stays positive under heavy load. I was hoping that maybe there is some better way of tracking these open channels?

  @Override
  protected void initChannel(SocketChannel channel) throws Exception {
          currentConnections.incrementAndGet();
          channel.closeFuture().addListener(f -> currentConnections.decrementAndGet());
  }

UPDATE: So the number stays positive after clients stop sending traffic and disconnect.

Upvotes: 0

Views: 1876

Answers (1)

Eran Harel
Eran Harel

Reputation: 2365

One way is to add a ChannelInboundHandler and override the channelRegistered and channelUnregistered like so:

  @Override
  public void channelRegistered(final ChannelHandlerContext ctx) {
    if (ctx.channel().remoteAddress() != null) {
      connections.inc();
    }
  }

  @Override
  public void channelUnregistered(final ChannelHandlerContext ctx) {
    currentConnections.dec();
  }

Another way is to only add the channel to a ChannelGroup when it's registered, and use ChannelGroup#size when you want to query the current connection count.

I guess the former incurs less overhead, but the later allows you to performs actions on all active channels if you need this sort of functionality anyway.

Upvotes: 1

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