mvcc: Optimize compaction for short commit pauses

mvcc/kvstore_compaction.go

@@ -30,7 +30,7 @@ func (s *store) scheduleCompaction(compactMainRev int64, keep map[revision]struc
 	end := make([]byte, 8)
 	binary.BigEndian.PutUint64(end, uint64(compactMainRev+1))
 
-	batchsize := int64(10000)
+	batchsize := int64(1000)
 	last := make([]byte, 8+1+8)
 	for {
 		var rev revision
@@ -68,10 +68,11 @@ func (s *store) scheduleCompaction(compactMainRev int64, keep map[revision]struc
 		// update last
 		revToBytes(revision{main: rev.main, sub: rev.sub + 1}, last)
 		tx.Unlock()
+		s.b.ForceCommit()
 		dbCompactionPauseMs.Observe(float64(time.Since(start) / time.Millisecond))
 
 		select {
-		case <-time.After(100 * time.Millisecond):
+		case <-time.After(10 * time.Millisecond):
 		case <-s.stopc:
 			return false
 		}