core/state, tests: fix memory leak via fastcache

core/blockchain.go

@@ -989,6 +989,7 @@ func (bc *BlockChain) Stop() {
 		if snapBase, err = bc.snaps.Journal(bc.CurrentBlock().Root); err != nil {
 			log.Error("Failed to journal state snapshot", "err", err)
 		}
+		bc.snaps.Release()
 	}
 	if bc.triedb.Scheme() == rawdb.PathScheme {
 		// Ensure that the in-memory trie nodes are journaled to disk properly.

core/state/snapshot/disklayer.go

@@ -45,6 +45,17 @@ type diskLayer struct {
 	lock sync.RWMutex
 }
 
+// Release releases underlying resources; specifically the fastcache requires
+// Reset() in order to not leak memory.
+// OBS: It does not invoke Close on the diskdb
+func (dl *diskLayer) Release() error {
+	if dl.cache != nil {
+		dl.cache.Reset()
+		dl.cache = nil
+	}
+	return nil
+}
+
 // Root returns  root hash for which this snapshot was made.
 func (dl *diskLayer) Root() common.Hash {
 	return dl.root

core/state/snapshot/snapshot.go

@@ -656,6 +656,13 @@ func diffToDisk(bottom *diffLayer) *diskLayer {
 	return res
 }
 
+// Release releases resources
+func (t *Tree) Release() {
+	if dl := t.disklayer(); dl != nil {
+		dl.Release()
+	}
+}
+
 // Journal commits an entire diff hierarchy to disk into a single journal entry.
 // This is meant to be used during shutdown to persist the snapshot without
 // flattening everything down (bad for reorgs).

tests/state_test_util.go

@@ -200,6 +200,9 @@ func (t *StateTest) Run(subtest StateSubtest, vmconfig vm.Config, snapshotter bo
 		if triedb != nil {
 			triedb.Close()
 		}
+		if snaps != nil {
+			snaps.Release()
+		}
 	}()
 	checkedErr := t.checkError(subtest, err)
 	if checkedErr != nil {