Avoid leaking more popped items (#8145)

cmd/sentry/sentry/sentry_grpc_server.go

@@ -112,7 +112,7 @@ func (bp *PeersByMinBlock) Pop() interface{} {
 	old := *bp
 	n := len(old)
 	x := old[n-1]
-	old[n-1] = PeerRef{}
+	old[n-1] = PeerRef{} // avoid memory leak
 	*bp = old[0 : n-1]
 	return x
 }

core/types/transaction.go

@@ -372,7 +372,7 @@ func (s *TxByPriceAndTime) Pop() interface{} {
 	old := *s
 	n := len(old)
 	x := old[n-1]
-	old[n-1] = nil
+	old[n-1] = nil // avoid memory leak
 	*s = old[0 : n-1]
 	return x
 }
@@ -500,6 +500,7 @@ func (t *TransactionsFixedOrder) Peek() Transaction {
 
 // Shift replaces the current best head with the next one from the same account.
 func (t *TransactionsFixedOrder) Shift() {
+	t.Transactions[0] = nil // avoid memory leak
 	t.Transactions = t.Transactions[1:]
 }
 
@@ -507,6 +508,7 @@ func (t *TransactionsFixedOrder) Shift() {
 // the same account. This should be used when a transaction cannot be executed
 // and hence all subsequent ones should be discarded from the same account.
 func (t *TransactionsFixedOrder) Pop() {
+	t.Transactions[0] = nil // avoid memory leak
 	t.Transactions = t.Transactions[1:]
 }
 

eth/gasprice/gasprice.go

@@ -197,7 +197,7 @@ func (t *transactionsByGasPrice) Pop() interface{} {
 	old := t.txs
 	n := len(old)
 	x := old[n-1]
-	old[n-1] = nil
+	old[n-1] = nil // avoid memory leak
 	t.txs = old[0 : n-1]
 	return x
 }
@@ -276,7 +276,7 @@ func (s *sortingHeap) Pop() interface{} {
 	old := *s
 	n := len(old)
 	x := old[n-1]
-	old[n-1] = nil
+	old[n-1] = nil // avoid memory leak
 	*s = old[0 : n-1]
 	return x
 }

turbo/stages/headerdownload/header_data_struct.go

@@ -197,7 +197,7 @@ func (iq *InsertQueue) Pop() interface{} {
 	old := *iq
 	n := len(old)
 	x := old[n-1]
-	old[n-1] = nil
+	old[n-1] = nil // avoid memory leak
 	*iq = old[0 : n-1]
 	x.idx = -1
 	x.queueId = NoQueue