Figure 8.5. The sequence of events in makeThumbnails6. Figure 8.5 illustrates the sequence of events in the makeThumbnails6 function. The vertical lines represent goroutines. The thin segments indicate sleep, the thick segments activity. The diagonal arrows indicate events that synchronize one goroutine with another. Time flows down. Notice how the main goroutine spends most of its time in the range loop asleep, waiting for a worker to send a value or the closer to close the channel.
