Deadlock when updating keys while iterating over them #315
Description
I don't see it stated anywhere that updating values while iterating isn't supported, so i'm assuming i'm not doing anything wrong?
Using the latest git version as of typing.
Running the following for a while (usually 10 seconds for me) will cause a deadlock (when the counter stays at 0 every second):
package main
import (
"fmt"
"github.com/dgraph-io/badger"
"math/rand"
"os"
"os/signal"
"sync/atomic"
"syscall"
"time"
)
var (
DB *badger.DB
updateCount = new(int64)
)
func panicErr(err error) {
if err != nil {
panic(err)
}
}
func main() {
opts := badger.DefaultOptions
opts.Dir = "db"
opts.ValueDir = "db"
opts.SyncWrites = false
var err error
DB, err = badger.Open(opts)
panicErr(err)
Load(0, 0xffff)
go ReaderWriter()
sc := make(chan os.Signal, 1)
signal.Notify(sc, syscall.SIGINT, syscall.SIGTERM, os.Interrupt, os.Kill)
ticker := time.NewTicker(time.Second)
for {
select {
case <-sc:
DB.Close()
return
case <-ticker.C:
numRead := atomic.SwapInt64(updateCount, 0)
fmt.Println("Read: ", numRead)
}
}
}
const vauleSize = 0xff
func Load(startOffset int64, amount int64) {
d := make([]byte, vauleSize)
for i := int64(0); i < amount; i++ {
panicErr(DB.Update(func(txn *badger.Txn) error {
rand.Read(d)
return txn.Set([]byte(fmt.Sprint(i+startOffset)), d)
}))
}
}
func ReaderWriter() {
for {
// Iterate over the db reading and upadting values
err := DB.Update(func(txn *badger.Txn) error {
opts := badger.DefaultIteratorOptions
opts.PrefetchValues = false
it := txn.NewIterator(opts)
defer it.Close()
i := 0
for it.Rewind(); it.Valid(); it.Next() {
i++
if i >= 100000 {
break
}
atomic.AddInt64(updateCount, 1)
item := it.Item()
key := item.Key()
newValue := make([]byte, vauleSize)
rand.Read(newValue)
item.Value()
err := txn.Set(key, newValue)
if err != nil {
return err
}
}
return nil
})
panicErr(err)
}
}