Documentation
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Overview ¶
Package errgroup provides synchronization, error propagation, and Context cancelation for groups of goroutines working on subtasks of a common task.
errgroup.Group is related to sync.WaitGroup but adds handling of tasks returning errors.
Index ¶
Examples ¶
Constants ¶
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Variables ¶
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Functions ¶
This section is empty.
Types ¶
type Group ¶
type Group struct {
// contains filtered or unexported fields
}
A Group is a collection of goroutines working on subtasks that are part of the same overall task.
A zero Group is valid, has no limit on the number of active goroutines, and does not cancel on error.
Example (JustErrors) ¶
JustErrors illustrates the use of a Group in place of a sync.WaitGroup to simplify goroutine counting and error handling. This example is derived from the sync.WaitGroup example at https://golang.org/pkg/sync/#example_WaitGroup.
Output:
Example (Parallel) ¶
Parallel illustrates the use of a Group for synchronizing a simple parallel task: the "Google Search 2.0" function from https://talks.golang.org/2012/concurrency.slide#46, augmented with a Context and error-handling.
Output: web result for "golang" image result for "golang" video result for "golang"
Example (Pipeline) ¶
Pipeline demonstrates the use of a Group to implement a multi-stage pipeline: a version of the MD5All function with bounded parallelism from https://blog.golang.org/pipelines.
Output:
func WithContext ¶
WithContext returns a new Group and an associated Context derived from ctx.
The derived Context is canceled the first time a function passed to Go returns a non-nil error or the first time Wait returns, whichever occurs first.
func (*Group) Go ¶
Go calls the given function in a new goroutine. It blocks until the new goroutine can be added without the number of active goroutines in the group exceeding the configured limit.
The first call to return a non-nil error cancels the group's context, if the group was created by calling WithContext. The error will be returned by Wait.
func (*Group) SetLimit ¶
SetLimit limits the number of active goroutines in this group to at most n. A negative value indicates no limit. A limit of zero will prevent any new goroutines from being added.
Any subsequent call to the Go method will block until it can add an active goroutine without exceeding the configured limit.
The limit must not be modified while any goroutines in the group are active.
Source Files