GO routine never exits based on stop condition - unable to find the reason

[Gowtham Raj]

In this example, we have a worker. The idea here is simulate clean shutdown of all go routines based on a condition.

In this case, go routines get spun - based on workers count. Each go routine reads the channel, does some work and sends output to the outputChannel.

The main go routine reads this output and prints it. To simulate a stop condition, the doneChannel is closed. Expected outcome is that select inside each go routine will pick this up and execute return which in turn will call the defer println. The actual output is that it never gets called and main exits.

Not sure what's the reason behind this.

Code at https://go.dev/play/p/-R7Llw9X_6U 

Can you please help to figure out the bug in this code.

[Sean Liao]

1. your generator never finished

2. your work channel still has things in it, there's no guarantee select will choose done first

3. reading from a closed channel will give you a zero value

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[Steven Hartland]

There is no guarantee that the select chooses the done case, so you need to check in work case as well e.g.

https://go.dev/play/p/zAj_qfO4uMA

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[Gowtham Raj]

Hello Steven,

Wow, this solved the problem. Never saw this pattern before. Thanks for your help !!

If you have any reference material for further reading for patterns like this can you please share them.

Regards,

Gowtham

[Steven Hartland]

No problem, there's a nice little write up on it stackoverflow.

[Gowtham Raj]

Great, thanks!