This file illustrates a panic in boltdb when lots of keys are deleted in a single transaction

try-to-crash.go

/*
 this file illustrates a panic in boltdb when lots of keys are deleted in a single transaction
 */
package main

import (
    "encoding/binary"
	"log"

	"github.com/boltdb/bolt"
)

/*
 insert 10,000,000 16-byte keys (with nil values) into a database
 then, try to delete all of them at once.
*/
func main() {
	db, err := bolt.Open("try-to-crash.bolt", 0600)
	if err != nil {
		panic(err)
	}
	defer db.Close()

    k := make([]byte, 16)

    // insert 10,000,000 keys (10000 transactions of 1000 keys a piece)
    for i := uint64(0); i < 10000; i++ {
        err := db.Update(func(tx *bolt.Tx) error {
            b, err := tx.CreateBucketIfNotExists([]byte("0"))
            if err != nil {
                return err
            }

            j := uint64(0)
            for ; j < 1000; j++ {
                binary.BigEndian.PutUint64(k[:8], i)
                binary.BigEndian.PutUint64(k[8:], j)
                b.Put(k, nil)

            }

            log.Println(i * j)

            return nil
        })

        if err != nil {
            panic(err)
        }
    }

    // delete all of them in one large transaction 
    db.Update(func(tx *bolt.Tx) error {
        b := tx.Bucket([]byte("0"))
        c := b.Cursor()
        i := 0
        for k, _ := c.First(); k != nil; k, _ = c.Next() {
            b.Delete(k)
            if i % 1000 == 0 {
                log.Println(i)
            }
            i++
        }

        return nil
    })

    /*
    You should get something like this panic:
    ...
    2014/06/05 20:52:23 9996000
    2014/06/05 20:52:23 9997000
    2014/06/05 20:52:23 9998000
    2014/06/05 20:52:23 9999000

    panic: tx 10002: page 79461 already freed in tx 10002

    goroutine 1 [running]:
    runtime.panic(0xa2b20, 0x24c9a12b0)
            /usr/local/go/src/pkg/runtime/panic.c:266 +0xb6
    github.com/boltdb/bolt.(*freelist).free(0x2102bd020, 0x2712, 0x2223b8b000)
            /Users/jordan/Development/experiments/gopath/src/github.com/boltdb/bolt/freelist.go:85 +0x3a8
    github.com/boltdb/bolt.(*node).spill(0x24d2b1b60, 0x24d2da5e0, 0x1dccb0)
            /Users/jordan/Development/experiments/gopath/src/github.com/boltdb/bolt/node.go:307 +0x1d6
    github.com/boltdb/bolt.(*node).spill(0x2103d9070, 0x24d2da5c0, 0x1dccb0)
            /Users/jordan/Development/experiments/gopath/src/github.com/boltdb/bolt/node.go:293 +0xc2
    github.com/boltdb/bolt.(*node).spill(0x2103d9000, 0x210395330, 0x22103e6b98)
            /Users/jordan/Development/experiments/gopath/src/github.com/boltdb/bolt/node.go:293 +0xc2
    github.com/boltdb/bolt.(*Bucket).spill(0x210395300, 0x210275f00, 0x1)
            /Users/jordan/Development/experiments/gopath/src/github.com/boltdb/bolt/bucket.go:543 +0x182
    github.com/boltdb/bolt.(*Bucket).spill(0x2102c5de8, 0x143833c2, 0x1dd220)
            /Users/jordan/Development/experiments/gopath/src/github.com/boltdb/bolt/bucket.go:514 +0x7bb
    github.com/boltdb/bolt.(*Tx).Commit(0x2102c5dd0, 0x0, 0x0)
            /Users/jordan/Development/experiments/gopath/src/github.com/boltdb/bolt/tx.go:159 +0x1a9
    github.com/boltdb/bolt.(*DB).Update(0x2102ad140, 0x22103e6f00, 0x0, 0x0)
            /Users/jordan/Development/experiments/gopath/src/github.com/boltdb/bolt/db.go:464 +0xe7
    main.main()
            /Users/jordan/Development/experiments/try-to-crash.go:61 +0x1c1
    exit status 2
    */
}