gojob is a simple job scheduler.
go get github.com/WangYihang/gojob
Create a job scheduler with a worker pool of size 32. To do this, you need to implement the Task interface.
// Task is an interface that defines a task
type Task interface {
// Do starts the task, returns error if failed
// If an error is returned, the task will be retried until MaxRetries
// You can set MaxRetries by calling SetMaxRetries on the scheduler
Do() error
}The whole code looks like this (try it online).
package main
import (
"fmt"
"net/http"
"github.com/WangYihang/gojob"
)
type MyTask struct {
Url string `json:"url"`
StatusCode int `json:"status_code"`
}
func New(url string) *MyTask {
return &MyTask{
Url: url,
}
}
func (t *MyTask) Do() error {
response, err := http.Get(t.Url)
if err != nil {
return err
}
t.StatusCode = response.StatusCode
defer response.Body.Close()
return nil
}
func main() {
var numTotalTasks int64 = 256
scheduler := gojob.New(
gojob.WithNumWorkers(8),
gojob.WithMaxRetries(4),
gojob.WithMaxRuntimePerTaskSeconds(16),
gojob.WithNumShards(4),
gojob.WithShard(0),
gojob.WithTotalTasks(numTotalTasks),
gojob.WithStatusFilePath("status.json"),
gojob.WithResultFilePath("result.json"),
gojob.WithMetadataFilePath("metadata.json"),
).
Start()
for i := range numTotalTasks {
scheduler.Submit(New(fmt.Sprintf("https://httpbin.org/task/%d", i)))
}
scheduler.Wait()
}Let's say you have a bunch of URLs that you want to crawl and save the HTTP response to a file. You can use gojob to do that. Check it out for details.
Try it out using the following command.
$ go run github.com/WangYihang/gojob/examples/complex-http-crawler@latest --help
Usage:
main [OPTIONS]
Application Options:
-i, --input= input file path
-o, --output= output file path
-r, --max-retries= max retries (default: 3)
-t, --max-runtime-per-task-seconds= max runtime per task seconds (default: 60)
-n, --num-workers= number of workers (default: 32)
Help Options:
-h, --help Show this help message$ cat urls.txt
https://www.google.com/
https://www.facebook.com/
https://www.youtube.com/$ go run github.com/WangYihang/gojob/examples/complex-http-crawler@latest -i input.txt -o output.txt -n 4
$ tail -n 1 output.txt
{
"started_at": 1708934911909748,
"finished_at": 1708934913160935,
"num_tries": 1,
"task": {
"url": "https://www.google.com/",
"http": {
"request": {
"method": "HEAD",
"url": "https://www.google.com/",
"host": "www.google.com",
// details omitted for simplicity
},
"response": {
"status": "200 OK",
"proto": "HTTP/2.0",
"header": {
"Alt-Svc": [
"h3=\":443\"; ma=2592000,h3-29=\":443\"; ma=2592000"
],
},
// details omitted for simplicity
"body": "",
}
}
},
"error": ""
}gojob provides metrics (num_total, num_finshed, num_succeed, num_finished) for Prometheus. You can use the following code to expose the metrics.
package main
func main() {
scheduler := gojob.New(
// All you need to do is just adding the following option to the scheduler constructor
gojob.WithPrometheusPushGateway("http://localhost:9091", "gojob"),
).Start()
}