benchmark/pub.js often crashes after benchmark/sub.js exits

[AlexeyKupershtokh]

ubuntu 11.04, node 0.8.12, axon 0.4.2

wicked@wicked-desktop:~/s2s/node_modules/axon/benchmark$ node pub.js
...
  axon:pub flushBatch to 1 sockets, 1 writable +0ms
  axon:pub flushBatch to 1 sockets, 0 writable +1ms
  ...
  axon:pub flushBatch to 1 sockets, 0 writable +0ms
  axon:sock disconnect 127.0.0.1:50770 +633ms
  axon:sock start total sockets: 1 +0ms
  axon:sock remove socket 0 +0ms
  axon:sock end total sockets: 0 +0ms
  axon:sock on('error') socket= +3ms { _handle: null,
  _pendingWriteReqs: 1481,
  _flags: 0,
  _connectQueueSize: 0,
  destroyed: true,
  errorEmitted: true,
  bytesRead: 0,
  _bytesDispatched: 72095400,
  allowHalfOpen: false,
  writable: false,
  readable: false,
  server: 
   { _events: { connection: [Function], listening: [Function] },
     _connections: 0,
     connections: [Getter/Setter],
     allowHalfOpen: false,
     _handle: 
      { writeQueueSize: 0,
        onconnection: [Function: onconnection],
        owner: [Circular] },
     _connectionKey: '4:0.0.0.0:3003' },
  _peername: { address: '127.0.0.1', family: 'IPv4', port: 50770 },
  _events: 
   { data: [Function],
     error: [Function],
     timeout: [Function],
     close: [Function] },
  _connecting: false,
  _connectQueue: null,
  _idleNext: null,
  _idlePrev: null,
  _idleTimeout: -1 }
  axon:sock error This socket is closed. +1ms
  axon:sock start total sockets: 0 +0ms
  axon:sock removal of unknown socket +0ms

events.js:68
        throw arguments[1]; // Unhandled 'error' event
                       ^
Error: This socket is closed.
    at Socket._write (net.js:518:19)
    at Socket.write (net.js:510:15)
    at PubSocket.flushBatch (/home/wicked/Alawar/s2s/node_modules/axon/lib/sockets/pub.js:60:14)
    at PubSocket.send (/home/wicked/Alawar/s2s/node_modules/axon/lib/sockets/pub.js:80:54)
    at more (/home/wicked/Alawar/s2s/node_modules/axon/benchmark/pub.js:21:42)
    at process.startup.processNextTick.process._tickCallback (node.js:244:9)  

I propose similar fix to pub.js as done here:
websockets/ws#74

PS: also note double socket removal, once on 'close' event then once on 'error'.

[AlexeyKupershtokh]

PS: I had to make debug more verbose as you see.

[gjohnson]

As far as the double removal, thats actually just debug info. One of the down sides of pushing in some new error handling last week was some hacky socket checking for the time being. Not positive if this error is related though... will take a peak later.

[AlexeyKupershtokh]

Added a pull request.
#62