Possible memory leak when opening a new DB by the commit buffer

[doron-cohen]

Describe the bug
Hi! We are using NutsDB as a temporary KV store on disk. We create the database, use it for a short period (few seconds up to a few minutes) and close it.
After running for a few hours we started to notice the memory growing constantly across runs. We ran a profiler to detect the issue and it shows createNewBufferWithSize is the cause:

I setup a quick test to benchmark and take a look inside:

func BenchmarkOpen(b *testing.B) {
	for i := 0; i < b.N; i++ {
		dbDir, err := os.MkdirTemp("", "state_********")
		require.NoError(b, err)
		defer os.RemoveAll(dbDir)

		db, err := nutsdb.Open(
			nutsdb.DefaultOptions,
			nutsdb.WithDir(dbDir),
		)
		require.NoError(b, err)

		err = db.Close()
		require.NoError(b, err)
	}
}

Note that I don't even run any transactions here. I am confused to why would it even leak. In our real code we do run some operations on init.

Ran it:

❯ go test -bench '^BenchmarkOpen$' -benchmem -memprofile memprofile.out package_name
/dirsync/core/state
goos: darwin
goarch: arm64
pkg: talon-sec.com/cloud-apps/apps/services/device-service/internal/modules/dirsync/core/state
BenchmarkOpen-10             338           4909304 ns/op         4270787 B/op        644 allocs/op
PASS
ok      package_name       4.137s

Looking at the mem profile I could see it does grow a lot only be running it 10 times:

❯ go tool pprof memprofile.out
(pprof) list Open
Total: 6.43GB
ROUTINE ======================== github.com/nutsdb/nutsdb.Open in /Users/docohen/.local/share/go/pkg/mod/github.com/nutsdb/nutsdb@v1.0.4/db.go
  512.09kB     6.42GB (flat, cum) 99.75% of Total
  512.09kB   512.09kB    123:func Open(options Options, ops ...Option) (*DB, error) {
         .          .    124:   opts := &options
         .          .    125:   for _, do := range ops {
         .          .    126:           do(opts)
         .          .    127:   }
         .     6.42GB    128:   return open(*opts)
         .          .    129:}
         .          .    130:
         .          .    131:// Update executes a function within a managed read/write transaction.
         .          .    132:func (db *DB) Update(fn func(tx *Tx) error) error {
         .          .    133:   if fn == nil {

Adding nutsdb.WithGCWhenClose(true) helps but this is still a problem:

(pprof) list Open
Total: 1.75GB
ROUTINE ======================== github.com/nutsdb/nutsdb.Open in /Users/docohen/.local/share/go/pkg/mod/github.com/nutsdb/nutsdb@v1.0.4/db.go
         0     1.75GB (flat, cum) 99.53% of Total
         .          .    123:func Open(options Options, ops ...Option) (*DB, error) {
         .          .    124:   opts := &options
         .          .    125:   for _, do := range ops {
         .          .    126:           do(opts)
         .          .    127:   }
         .     1.75GB    128:   return open(*opts)
         .          .    129:}
         .          .    130:
         .          .    131:// Update executes a function within a managed read/write transaction.
         .          .    132:func (db *DB) Update(fn func(tx *Tx) error) error {
         .          .    133:   if fn == nil {

Only adding nutsdb.WithCommitBufferSize(0) reduces it to a normal size:

(pprof) list Open
Total: 47.19MB
ROUTINE ======================== github.com/nutsdb/nutsdb.Open in /Users/docohen/.local/share/go/pkg/mod/github.com/nutsdb/nutsdb@v1.0.4/db.go
         0    33.54MB (flat, cum) 71.08% of Total
         .          .    123:func Open(options Options, ops ...Option) (*DB, error) {
         .          .    124:   opts := &options
         .          .    125:   for _, do := range ops {
         .          .    126:           do(opts)
         .          .    127:   }
         .    33.54MB    128:   return open(*opts)
         .          .    129:}
         .          .    130:
         .          .    131:// Update executes a function within a managed read/write transaction.
         .          .    132:func (db *DB) Update(fn func(tx *Tx) error) error {
         .          .    133:   if fn == nil {

To Reproduce
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What actually happens
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please complete the following information :

• OS: Locally on a mac. In production under Alpine linux in a container.
• NutsDB Version v1.0.4

Additional context
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