Blocking i/o (perfectly synchronized):

worker1: 2ms to finish
worker2: 2ms to finish
worker3: 2ms to finish

server reads result: 0.5ms (r)
server writes new job: 0.5ms (w)

time:     0     1     2     3     4     5     6     7
worker1:  rrrwww            rrrwww
worker2:        rrrwww            rrrwww
worker3:              rrrwww            rrrwww

-----------------------------------------------------------

Blocking i/o (not synchronized):

worker1: 3ms to finish
worker2: 2ms to finish
worker3: 1ms to finish

server reads result: 0.5ms (r)
server writes new job: 0.5ms (w)
cpu time available for extra non-i/o work: (+)
waiting for i/o: (.)

time:     0     1     2     3     4     5     6     7
worker1:  rrrwww                  rrrwww
worker2:  ......rrrwww            ......rrrwww
worker3:  ............rrrwww      ............rrrwww
server:                     ......

-----------------------------------------------------------

Non-blocking i/o (perfectly synchronized):

worker1: 2ms to finish
worker2: 2ms to finish
worker3: 2ms to finish

server reads result: 0.5ms (r)
server writes new job: 0.5ms (w)
cpu time available for extra non-i/o work: (+)
waiting for i/o: (.)

time:     0     1     2     3     4     5     6     7
worker1:  r++r++r++w++w++w            r++r++r++w++w++w
worker2:   r++r++r++w++w++w            r++r++r++w++w++w
worker3:    r++r++r++w++w++w            r++r++r++w++w++w
server:                     ++++++++++

-----------------------------------------------------------

Non-blocking i/o (not synchronized):

worker1: 3ms to finish
worker2: 2ms to finish
worker3: 1ms to finish

server reads result: 0.5ms (r)
server writes new job: 0.5ms (w)
cpu time available for extra non-i/o work: (+)
waiting for i/o: (.)

time:     0     1     2     3     4     5     6     7
worker1:  r++r++r++w++w++w                  r+r+rwww
worker2:   r++r++r++w++w++w            r+rrw+w+w
worker3:    r++r++r++w++w++w      rrrww+w
server:                     ++++++

-----------------------------------------------------------


Blocking i/o:
-------------

Server:

  results = []
  stream_socket_server
  while ( unfinished jobs )
    stream_socket_accept
    while ( got data )
      stream_socket_recvfrom
    results[] = data
    stream_socket_sendto
    fclose

Worker:

  stream_socket_client
  stream_socket_sendto [register worker with server]
  stream_socket_recvfrom [get first job from server]
  while ( got job )
    stream_socket_sendto [send result]
    stream_socket_recvfrom [get another job]


Non-blocking i/o:
-----------------

Server:

  clients = []
  writeBufferPerClient = []
  readBufferPerClient = []
  stream_socket_server
  stream_set_blocking( server socket not blocking )
  while ( unfinished jobs )
    stream_select( readable: clients + server, writable: clients )
    if ( server is readable )
      clients[] = stream_socket_accept
      stream_set_blocking( client socket not blocking )
    foreach ( clients[] )
      if ( is readable )
        while ( got data, which means client socket is open )
          stream_socket_recvfrom
          readBufferPerClient[] .= data
        if ( no received data )
          results[] = Request(readBuffer)->getBody/Headers()
      if ( is writable )
        while ( didn't write all bytes of writeBufferPerClient[current] yet )
          stream_socket_sendto
        if ( writeBufferPerClient[current] is empty )
          fclose
          unset( clients[current] )

Worker:

  initialized = false
  jobQueue = []
  resultsQueue = []
  readBuffer = ''
  writeBuffer = ''
  stream_socket_client
  stream_set_blocking( client socket not blocking )
  while ( true )
    stream_select( readable: server, writable: server )
    if ( server is writable )
      if ( !initialized )
        writeBuffer = I'm a new worker, register me
      else
        writeBuffer = here's a job result resultsQueue.pop(), gimme another job
      while ( didn't write all bytes of writeBuffer yet )
        stream_socket_sendto
      if ( writeBuffer is empty )
        fclose
    if ( server is readable )
      while ( got data, which means client socket is open )
        stream_socket_recvfrom
        readBuffer .= data
      if ( no received data )
        jobQueue[] = Request(readBuffer)->getBody/Headers()