Comment by evanelias

Comment by evanelias 13 hours ago

5 replies

You can just use golang.org/x/sync/errgroup instead, which has always provided this style of use.

errgroup also has other niceties like error propagation, context cancellation, and concurrency limiting.

Cyph0n 12 hours ago

Context cancellation is not always desirable. I personally have been bitten multiple times by the default behavior of errgroup.

  • CamouflagedKiwi 11 hours ago

    You have to explicitly propagate the group's context if you want it to cancel. You can just not do that if you don't want - there certainly are cases for that.

porridgeraisin 12 hours ago

errgroup cancels the whole task if even one subtask fails however. That is not desirable always.

  • Groxx 11 hours ago

    It does not, which is easy to verify from the source. Every func passed in is always run (with the exception of TryGo which is explicitly "maybe").

    At best, using the optional, higher-effort errgroup.WithContext will cancel the context but still run all of your funcs. If you don't want that for one of the funcs, or some component of them, just don't use the context.

  • evanelias 10 hours ago

    If the context cancellation is undesirable, you just choose not to use WithContext, as the sibling comment mentions.

    You could also just make your subtask function return nil always, if you just want to get the automatic bookkeeping call pattern (like WaitGroup.Go from Golang 1.25), plus optional concurrency limiting.

    Also note, even if a subtask function returns an error, the errgroup Wait blocking semantics are identical to those of a WaitGroup. Wait will return the first error when it returns, but it doesn't unblock early on first error.