errgroup's Introduction

errgroup

The errgroup package is an extension of the sync/errgroup package, and its core is to manage the behavior of a set of gotoutines. Control the behavior of other goroutines in the group when error or panic occurs: cancel all executions or continue all executions.

Install

go get -u github.com/fanjindong/errgroup

Fast Start

errgroup contains three common methods

NewContinue At this point, all tasks will not be cancelled because one task failed

eg := &errgroup.NewContinue(ctx)
eg.Go(func (ctx context.Context) {
    // NOTE: In this case, ctx is the ctx passed by NewContinue
    // do something
})
eg.Wait()

NewCancel If one task fails, all pending or ongoing tasks will be cancelled

eg := errgroup.NewCancel(ctx)
eg.Go(func (ctx context.Context) {
    // NOTE: At this point ctx is derived from the ctx passed in WithContext
    // do something
})
eg.Wait()

Setting the maximum number of parallelism SetMaxProcess works for all the above uses

eg := errgroup.NewCancel(ctx, WithMaxProcess(2))
// task1
eg.Go(func(ctx context.Context) {
    fmt.Println("task1")
})
// task2
eg.Go(func (ctx context.Context) {
    fmt.Println("task2")
})
// task3
eg.Go(func (ctx context.Context) {
    fmt.Println("task3")
})
eg.Wait()
// NOTE: At this point, WithMaxProcess is set to 2,
// Added task1, task2, task3 ,
// Initially, only two tasks will run, and the last task will not be executed until one task is complete.