Signal exit condition without closing the jobs channel

<p><a href="https://play.golang.org/p/VMzNWjH3j3">https://play.golang.org/p/VMzNWjH3j3</a></p> <p>The workers can post additional jobs to the jobs queue, so I can&#39;t <code>close(jobs)</code> in the main goroutine and wait for the workers to exit (send on a closed channel will panic). And I can&#39;t devise another way to tell the workers that there will be no more work. Is there a way?</p> <hr/>**评论：**<br/><br/>Cidan: <pre><p>Yes, this is what context + select statements are for!</p> <p><a href="https://play.golang.org/p/hS6ajt2Lcu">https://play.golang.org/p/hS6ajt2Lcu</a></p> <p>Here you can see we did a few things:</p> <ol> <li>We created a context with cancel function in main</li> <li>We pass the context to the worker</li> <li>The worker now does a for{} and select{}</li> <li>The select statement will get a job from the queue if there is one, otherwise it waits for ctx.Done() to return -- note that ctx.Done() blocks forever, and the select statement will just keep reading from whatever channel unblocks first</li> <li>We sleep for one second in main</li> <li>We call the cancel() function, which causes ctx.Done() to close, and in turn exits us from the worker loop.</li> </ol> <p>Hope this helps, :)</p></pre>robe_and_wizard_hat: <pre><p>Why do you break out of the loop with a <code>break work</code> instead of just returning from the method?</p></pre>brokedown: <pre><p>In this case it doesn&#39;t matter but as a guide to follow that allows you to do any janitorial steps you may have after before returning.</p></pre>Nooby1990: <pre><p>You could maybe add a context.Context and close the channel when the Context is cancelled. Just have some routine (maybe main) wait for Context.Done() and close the channel afterwards. When there will be no more work just call the cancel function. The tricky part will be to detect when there is no more work and this will be dependent on the business logic you are building there.</p></pre>