Hello,
Does anybody know of some reference code or common patterns I can use to
keep track of worker goroutines? For context, I want a user to be able to
issue a "stop" command using a CLI tool which will prompt my server to
gracefully terminate one of my workers.
For example, when a user issues a "start" command through a CLI tool, this
will signal my server to spawn a goroutine that perpetually runs and polls
an HTTP endpoint until a user initiates a "stop" command. When the user
issues a "stop" command through the same CLI tool, I want the server to be
able to signal the goroutine to stop. Any reference code would be much
appreciated!
One approach I thought of was by passing a `context.WithCancel()` and
holding a reference to the cancel function in a global map (with the worker
ID as keys). When the user issues a "stop" command against the worker ID,
another function is executed which calls the context's cancel function.
Example code below (appreciate this is horrendously breaking a lot of
rules, but I want to focus only on the elements around passing the cancel
function around - happy to discuss anything else that is of concern to
someone though):
```
// invoked when a CLI start subcommand is issued to my main CLI tool
func (w *WorkerGroup) Start(ctx context.Context, id string) {
_, cancel := context.WithCancel(ctx)
w.Workers.Lock()
w.Workers[id] := cancel
w.Workers.Unlock()
go startWorker(id)
}
// invoked when a CLI stop subcommand is issued to my main CLI tool
func (w *WorkerGroup) Stop(id string) {
cancelWorker := w.Workers[id]
cancelWorker()
}
```
I have read that passing a context's cancel function around is a bad idea,
but in an example like this, is it justified?
Thanks in advance to any help!
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