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https://github.com/veggiemonk/batch
Split an array/slice into n evenly chunks. Spread load evenly across workers
https://github.com/veggiemonk/batch
batch cloud-run cloud-run-jobs go go-generics golang jobs
Last synced: 2 months ago
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Split an array/slice into n evenly chunks. Spread load evenly across workers
- Host: GitHub
- URL: https://github.com/veggiemonk/batch
- Owner: veggiemonk
- License: apache-2.0
- Created: 2022-10-15T20:46:29.000Z (almost 2 years ago)
- Default Branch: main
- Last Pushed: 2024-02-11T22:50:22.000Z (8 months ago)
- Last Synced: 2024-06-20T15:02:00.763Z (3 months ago)
- Topics: batch, cloud-run, cloud-run-jobs, go, go-generics, golang, jobs
- Language: Go
- Homepage:
- Size: 18.6 KB
- Stars: 5
- Watchers: 3
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
- awesome-golang-repositories - batch
README
# Batch
[](https://pkg.go.dev/github.com/veggiemonk/batch)
Split an array/slice into `n` evenly chunks.
Inspired from the blog post by [Paul Di Gian](https://github.com/PaulDiGian) on his blog:
[Split a slice or array in a defined number of chunks in golang](https://pauldigian.com/split-a-slice-or-array-in-a-defined-number-of-chunks-in-golang-but-any-language-really)
**Note**: you might better off just copying the function into your codebase.
It has little code.
See [Go Proverbs](https://go-proverbs.github.io/) for more details.
> A little copying is better than a little dependency.
This library isn't really meant to be imported.
Just copy the one function and adapt it to your needs.
Look at the [tests](batch_test.go) for edge cases.
The benchmarks and fuzzing are just for me to learn and have a playground
to try things out.
- [Batch](#batch)
- [Installation](#installation)
- [Usage](#usage)
- [Usage with Cloud Run Jobs](#usage-with-cloud-run-jobs)
- [Rationale](#rationale)
- [Links](#links)
## Installation
Requires Go 1.18 or later.
Just copy the function in [batch.go](batch.go)
## Usage
```go
package main
import (
"fmt"
"github.com/veggiemonk/batch"
)
func main() {
s := []int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
// Split the slice into 3 even parts
chunks := batch.Slice(s, 3)
fmt.Println(chunks)
// length 3 3 4
// output: [[1 2 3] [4 5 6] [7 8 9 10]]
// the size of each batch has variation of max 1 item
// this can spread the load evenly amongst workers
}
```
## Usage with Cloud Run Jobs
```go
batchID = uuid.New().String()
taskCount, _ = strconv.Atoi(os.Getenv("CLOUD_RUN_TASK_COUNT"))
taskIndex, _ = strconv.Atoi(os.Getenv("CLOUD_RUN_TASK_INDEX"))
tt, _ := requestToTasks(request)
batches := batch.Slice(tt, taskCount)
if taskIndex >= len(batches) || taskIndex < 0 {
return fmt.Errorf("index (%d) out of bounds (max: %d), (id:%s): %w", taskIndex, len(batches), batchID, ErrTaskIndexOutOfBounds)
}
b := batches[taskIndex]
if err := process(b); err != nil {
return fmt.Errorf("failed to process batch (id:%s): %w", batchID, err)
}
```
## Rationale
Having (almost) same sized batch is useful when you want to distribute the workload evenly across multiple workers.
As opposed to defining the _size of each batch_, we define the _number of batch we want_ to have.
Here a **counter** example:
```go
actions := []int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
batchSize := 3
batches := make([][]int, 0, (len(actions) + batchSize - 1) / batchSize)
for batchSize < len(actions) {
actions, batches = actions[batchSize:], append(batches, actions[0:batchSize:batchSize])
}
batches = append(batches, actions)
fmt.Println(result)
// length 4 | 4 | 2
// output: [[1 2 3 4] [5 6 7 8] [9 10]]
// 2 workers will do double the work of the last worker.
// --> Not what we want.
}
```
This is not ideal when you want to distribute the workload evenly across multiple workers.
The code was taken from [Go wiki - Slice Tricks](https://go.dev/wiki/SliceTricks#batching-with-minimal-allocation).
[//]: # "can be played with here: https://go.dev/play/p/-ULiql4tOTc"
## Links
- [Split a slice or array in a defined number of chunks in golang](https://pauldigian.com/split-a-slice-or-array-in-a-defined-number-of-chunks-in-golang-but-any-language-really)
- [Go wiki - Slice Tricks](https://go.dev/wiki/SliceTricks#batching-with-minimal-allocation)