hystrix-go Documentation

The load testing integration app is used to measure the behavior of circuits under load. You can run the service using go run and optionally specify a Statsd host for metrics collection using the -statsd flag.

go run service/main.go -statsd mystatsdhost:8125

You can export Hystrix metrics to Statsd by initializing a Statsd collector and registering it with the metric collector registry.

c, err := plugins.InitializeStatsdCollector(&plugins.StatsdCollectorConfig{
	StatsdAddr: "localhost:8125",
	Prefix:     "myapp.hystrix",
})
if err != nil {
	log.Fatalf("could not initialize statsd client: %v", err)
}

metricCollector.Registry.Register(c.NewStatsdCollector)

To visualize command metrics using a Hystrix Dashboard, register an event stream HTTP handler. You should run this handler in a goroutine on a dedicated port.

hystrixStreamHandler := hystrix.NewStreamHandler()
hystrixStreamHandler.Start()
go http.ListenAndServe(net.JoinHostPort("", "81"), hystrixStreamHandler)

Since hystrix.Go returns an error channel, you can use a select statement to wait for either your application's output or a Hystrix error.

output := make(chan bool, 1)
errors := hystrix.Go("my_command", func() error {
	// talk to other services
	output <- true
	return nil
}, nil)

select {
case out := <-output:
	// success
case err := <-errors:
	// failure
}

Once the integration app is running, you can use Apache Benchmark (ab) to simulate high concurrency and request volume against the service (defaulting to http://localhost:8888/).

ab -n 10000000 -c 10 http://localhost:8888/

To handle service outages gracefully, provide a second function to hystrix.Go. This fallback function is triggered when your primary logic returns an error or when Hystrix determines the service is unhealthy (e.g., due to timeouts or circuit breaker trips).

hystrix.Go("my_command", func() error {
	// talk to other services
	return nil
}, func(err error) error {
	// do this when services are down
	return nil
})

Use hystrix.Go to run application logic that relies on external systems in a separate goroutine. This function returns a channel of errors that you can monitor to determine if the command succeeded or failed.

import "github.com/afex/hystrix-go/hystrix"

errors := hystrix.Go("my_command", func() error {
	// talk to other services
	return nil
}, nil)

If you need to wait for a command to finish immediately, use hystrix.Do. This function blocks until the command completes and returns a single error.

err := hystrix.Do("my_command", func() error {
	// talk to other services
	return nil
}, nil)