glow

Examples are in this repo https://github.com/chrislusf/glow_examples

Purpose

Glow is providing a library to easily compute in parallel threads or distributed to clusters of machines.

Installation

go get github.com/chrislusf/glow
go get github.com/chrislusf/glow/flow

One minute tutorial

Simple Start

Here is a simple full example:

package main

import (
	"flag"
	"strings"

	"github.com/chrislusf/glow/flow"
)

func main() {
	flag.Parse()

	flow.New().TextFile(
		"/etc/passwd", 3,
	).Filter(func(line string) bool {
		return !strings.HasPrefix(line, "#")
	}).Map(func(line string, ch chan string) {
		for _, token := range strings.Split(line, ":") {
			ch <- token
		}
	}).Map(func(key string) int {
		return 1
	}).Reduce(func(x int, y int) int {
		return x + y
	}).Map(func(x int) {
		println("count:", x)
	}).Run()
}

Try it.

./word_count

It will run the input text file, '/etc/passwd', in 3 go routines, filter/map/map, and then reduced to one number in one goroutine (not exactly one goroutine, but let's skip the details for now.) and print it out.

This is useful already, saving lots of idiomatic but repetitive code on channels, sync wait, etc.

However, there is one more thing!

Scale it out

To setup the Glow cluster, we do not need experts on Zookeeper/HDFS/Mesos/YARN etc. Just build or download one binary file.

Setup the cluster

  // fetch and install via go, or just download it from somewhere
  go get github.com/chrislusf/glow
  // start a master on one computer
  glow master
  // run one or more agents on computers
  glow agent --dir . --max.executors=16 --memory=2048 --master="localhost:8930" --port 8931

Glow Master and Glow Agent run very efficiently. They take about 6.5MB and 5.5MB memory respectively in my environments. I would recommend set up agents on any server you can find. You can tap into the computing power whenever you need to.

Start the driver program

To leap from one computer to clusters of computers, add this line to the import list:

	_ "github.com/chrislusf/glow/driver"

This will "steroidize" the code to run in cluster mode!

./word_count -glow -glow.leader="localhost:8930"

The word_count program will become a driver program, dividing the execution into a directed acyclic graph(DAG), and send tasks to agents.

[Glow Introduction Slides] (https://raw.githubusercontent.com/chrislusf/glow/master/etc/GlowIntroduction.pdf)
Wiki page: https://github.com/chrislusf/glow/wiki
Mailing list: https://groups.google.com/forum/#!forum/glow-user-discussion
Examples: https://github.com/chrislusf/glow_examples/tree/master/word_count

Contribution

Start using it! And report or fix any issue you have seen, add any feature you want.

Fork it, code it, and send pull requests. Better first discuss about the feature you want on the mailing list. https://groups.google.com/forum/#!forum/glow-user-discussion

License

http://www.apache.org/licenses/LICENSE-2.0

miminus/glow