Netty: Number of outstanding requests

Question

In apache, there is server-status page which tells me the current status of the server. In particular, it tells me the number of requests currently ('currently' as in, at the time when the server-status page is accessed) being processed. Is there some way to find out the same in Netty?

Answer 1

It's not built in, but conceptually it is easy to implement (or easy to describe, anyways ;) )

1. Create a Sharable ChannelHandler:
   • Implements ChannelUpstreamHandler
   • Implements ChannelDownstreamHandler
   • Add an AtomicInteger field inFlightRequests which is incremented on up, and decremented on down.
   • Expose the inFlightRequests through JMX so you can monitor the value.
   • You should also decrement inFlightRequests in a SimpleChannelUpstreamHandler.exeptionCaught callback. You might want to add an errors counter like the inFlightRequests counter which is incremented on caught exceptions.
2. Add the [same] ChannelHandler instance to all created pipelines as the first handler.