GC doesn't seem to run

[lkp-k]

What version of Badger are you using?

Latest v4

What version of Go are you using?

1.20.3

Have you tried reproducing the issue with the latest release?

Yes

What is the hardware spec (RAM, CPU, OS)?

16gb ram, i5 intel, mac os

What steps will reproduce the bug?

package main

import (
	"fmt"
	"log"
	"math/rand"
	"strconv"
	"time"

	"github.com/dgraph-io/badger/v4"
)

var db *badger.DB

const charset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"

func generateRandomString(length int) string {
	b := make([]byte, length)
	for i := range b {
		b[i] = charset[rand.Intn(len(charset))]
	}
	return string(b)
}

func main() {
	opts := badger.DefaultOptions("badger")
	opts.ValueLogFileSize = 1 << 20
	var err error
	db, err = badger.Open(opts)
	if err != nil {
		log.Fatal(err)
	}
	defer db.Close()

	fmt.Println("Start inserting 5 million items.")

	for i := 0; i < 5_000_000; i++ {
		err := db.Update(func(txn *badger.Txn) error {
			key := strconv.Itoa(i)
			value := []byte(generateRandomString(300))

			e := badger.NewEntry([]byte(key), value).WithTTL(30 * time.Second)

			err := txn.SetEntry(e)
			if err != nil {
				return err
			}
			return nil
		})

		if err != nil {
			log.Fatal("Error while inserting:", err)
		}
	}

	fmt.Println("Successfully inserted 5 million items.")

	startGarbageCollection()
}

func startGarbageCollection() {
	ticker := time.NewTicker(10 * time.Second)
	defer ticker.Stop()
	for range ticker.C {
	again:
		err := db.RunValueLogGC(0.01)
		fmt.Println(err)
		if err == nil {
			goto again
		}
	}
}

Expected behavior and actual result.

Since the keys are expiring in 30 seconds, I thought that the files in badger/ would get removed.

However, heres what I see:

Additional information

No response

[Aman Mangal]

may be related to #1995. Thanks for filling an issue with code to reproduce. I will try to find some time to look into it.

[Yang Wang]

Maybe the compaction is not triggered. Similar to https://discuss.dgraph.io/t/gc-may-not-work-in-some-cases/17197

[lkp-k]

Hi Friends. Any updates on this? Ty