diff --git a/sync/src/parallel/executor.rs b/sync/src/parallel/executor.rs
index 4b61ff3980..4735f2a769 100644
--- a/sync/src/parallel/executor.rs
+++ b/sync/src/parallel/executor.rs
@@ -14,6 +14,8 @@ use tokio::{
     task::JoinHandle,
 };
 
+const MAX_TOTAL_WAITING_TIME: u64 = 3600000; // an hour
+
 #[derive(Debug)]
 pub enum ExecuteState {
     Executing(HashValue),
@@ -96,6 +98,8 @@ impl DagBlockExecutor {
                             block.header().id()
                         );
 
+                        let mut total_waiting_time: u64 = 0;
+                        let waiting_per_time: u64 = 100;
                         loop {
                             match Self::waiting_for_parents(
                                 &self.dag,
@@ -104,9 +108,34 @@ impl DagBlockExecutor {
                             ) {
                                 Ok(true) => break,
                                 Ok(false) => {
+                                    if total_waiting_time >= MAX_TOTAL_WAITING_TIME {
+                                        error!(
+                                            "failed to check parents: {:?}, for reason: timeout",
+                                            header
+                                        );
+                                        match self
+                                            .sender
+                                            .send(ExecuteState::Error(Box::new(header.clone())))
+                                            .await
+                                        {
+                                            Ok(_) => (),
+                                            Err(e) => {
+                                                error!(
+                                                    "failed to send error state: {:?}, for reason: {:?}",
+                                                    header, e
+                                                );
+                                                return;
+                                            }
+                                        }
+                                        return;
+                                    }
                                     tokio::task::yield_now().await;
-                                    tokio::time::sleep(tokio::time::Duration::from_millis(100))
-                                        .await
+                                    tokio::time::sleep(tokio::time::Duration::from_millis(
+                                        waiting_per_time,
+                                    ))
+                                    .await;
+                                    total_waiting_time =
+                                        total_waiting_time.saturating_add(waiting_per_time);
                                 }
                                 Err(e) => {
                                     error!(
diff --git a/sync/src/parallel/sender.rs b/sync/src/parallel/sender.rs
index 4d30510b01..e0fd9316cb 100644
--- a/sync/src/parallel/sender.rs
+++ b/sync/src/parallel/sender.rs
@@ -26,7 +26,7 @@ struct DagBlockWorker {
 }
 
 pub struct DagBlockSender<'a> {
-    sync_dag_store: SyncDagStore,
+    sync_dag_store: Arc<SyncDagStore>,
     executors: Vec<DagBlockWorker>,
     queue_size: usize,
     time_service: Arc<dyn TimeService>,
@@ -38,7 +38,7 @@ pub struct DagBlockSender<'a> {
 
 impl<'a> DagBlockSender<'a> {
     pub fn new(
-        sync_dag_store: SyncDagStore,
+        sync_dag_store: Arc<SyncDagStore>,
         queue_size: usize,
         time_service: Arc<dyn TimeService>,
         storage: Arc<dyn Store>,
diff --git a/sync/src/sync.rs b/sync/src/sync.rs
index 4778a9a566..b57e5590e3 100644
--- a/sync/src/sync.rs
+++ b/sync/src/sync.rs
@@ -62,6 +62,7 @@ pub struct SyncService {
     stage: SyncStage,
     config: Arc<NodeConfig>,
     storage: Arc<Storage>,
+    sync_dag_store: Arc<SyncDagStore>,
     metrics: Option<SyncMetrics>,
     peer_score_metrics: Option<PeerScoreMetrics>,
     vm_metrics: Option<VMMetrics>,
@@ -83,6 +84,13 @@ impl SyncService {
         let head_block_info = storage
             .get_block_info(head_block_hash)?
             .ok_or_else(|| format_err!("can't get block info by hash {}", head_block_hash))?;
+        let sync_dag_store = Arc::new(SyncDagStore::create_from_path(
+            config.storage.sync_dir(),
+            SyncDagStoreConfig::create_with_params(
+                config.storage.cache_size(),
+                RocksdbConfig::default(),
+            ),
+        )?);
         //TODO bail PrometheusError after use custom metrics registry.
         let metrics = config
             .metrics
@@ -97,6 +105,7 @@ impl SyncService {
             stage: SyncStage::NotStart,
             config,
             storage,
+            sync_dag_store,
             metrics,
             peer_score_metrics,
             vm_metrics,
@@ -226,13 +235,7 @@ impl SyncService {
         let sync_metrics = self.metrics.clone();
         let vm_metrics = self.vm_metrics.clone();
         let dag = ctx.get_shared::<BlockDAG>()?;
-        let sync_dag_store = SyncDagStore::create_from_path(
-            config.storage.sync_dir(),
-            SyncDagStoreConfig::create_with_params(
-                config.storage.cache_size(),
-                RocksdbConfig::default(),
-            ),
-        )?;
+        let sync_dag_store = self.sync_dag_store.clone();
         let fut = async move {
             let startup_info = storage
                 .get_startup_info()?
diff --git a/sync/src/tasks/block_sync_task.rs b/sync/src/tasks/block_sync_task.rs
index e68ae73db8..95c03ad8ce 100644
--- a/sync/src/tasks/block_sync_task.rs
+++ b/sync/src/tasks/block_sync_task.rs
@@ -214,7 +214,7 @@ pub struct BlockCollector<N, H> {
     local_store: Arc<dyn Store>,
     fetcher: Arc<dyn BlockFetcher>,
     latest_block_id: HashValue,
-    sync_dag_store: SyncDagStore,
+    sync_dag_store: Arc<SyncDagStore>,
 }
 
 impl<N, H> ContinueChainOperator for BlockCollector<N, H>
@@ -264,7 +264,7 @@ where
         skip_pow_verify: bool,
         local_store: Arc<dyn Store>,
         fetcher: Arc<dyn BlockFetcher>,
-        sync_dag_store: SyncDagStore,
+        sync_dag_store: Arc<SyncDagStore>,
     ) -> Self {
         let latest_block_id = chain.current_header().id();
         Self {
diff --git a/sync/src/tasks/continue_execute_absent_block.rs b/sync/src/tasks/continue_execute_absent_block.rs
index 0e3c3bebce..18c288af84 100644
--- a/sync/src/tasks/continue_execute_absent_block.rs
+++ b/sync/src/tasks/continue_execute_absent_block.rs
@@ -19,14 +19,14 @@ pub trait ContinueChainOperator {
 pub struct ContinueExecuteAbsentBlock<'a> {
     operator: &'a mut dyn ContinueChainOperator,
     local_store: Arc<dyn Store>,
-    sync_dag_store: SyncDagStore,
+    sync_dag_store: Arc<SyncDagStore>,
 }
 
 impl<'a> ContinueExecuteAbsentBlock<'a> {
     pub fn new(
         operator: &'a mut dyn ContinueChainOperator,
         local_store: Arc<dyn Store>,
-        sync_dag_store: SyncDagStore,
+        sync_dag_store: Arc<SyncDagStore>,
     ) -> anyhow::Result<ContinueExecuteAbsentBlock<'a>> {
         anyhow::Result::Ok(ContinueExecuteAbsentBlock {
             operator,
diff --git a/sync/src/tasks/inner_sync_task.rs b/sync/src/tasks/inner_sync_task.rs
index 7d91778143..8b0434961d 100644
--- a/sync/src/tasks/inner_sync_task.rs
+++ b/sync/src/tasks/inner_sync_task.rs
@@ -38,7 +38,7 @@ where
     peer_provider: N,
     custom_error_handle: Arc<dyn CustomErrorHandle>,
     dag: BlockDAG,
-    sync_dag_store: SyncDagStore,
+    sync_dag_store: Arc<SyncDagStore>,
 }
 
 impl<H, F, N> InnerSyncTask<H, F, N>
@@ -58,7 +58,7 @@ where
         peer_provider: N,
         custom_error_handle: Arc<dyn CustomErrorHandle>,
         dag: BlockDAG,
-        sync_dag_store: SyncDagStore,
+        sync_dag_store: Arc<SyncDagStore>,
     ) -> Self {
         Self {
             ancestor,
diff --git a/sync/src/tasks/mock.rs b/sync/src/tasks/mock.rs
index 96b9822d1b..ac22c1112f 100644
--- a/sync/src/tasks/mock.rs
+++ b/sync/src/tasks/mock.rs
@@ -135,7 +135,7 @@ pub struct SyncNodeMocker {
     pub peer_id: PeerId,
     pub chain_mocker: MockChain,
     pub err_mocker: ErrorMocker,
-    pub sync_dag_store: SyncDagStore,
+    pub sync_dag_store: Arc<SyncDagStore>,
     peer_selector: PeerSelector,
 }
 
@@ -155,8 +155,10 @@ impl SyncNodeMocker {
             None,
         );
         let peer_selector = PeerSelector::new(vec![peer_info], PeerStrategy::default(), None);
-        let sync_dag_store = SyncDagStore::create_for_testing()
-            .context("Failed to create SyncDagStore for testing")?;
+        let sync_dag_store = Arc::new(
+            SyncDagStore::create_for_testing()
+                .context("Failed to create SyncDagStore for testing")?,
+        );
         Ok(Self::new_inner(
             peer_id,
             chain,
@@ -186,7 +188,7 @@ impl SyncNodeMocker {
             None,
         );
         let peer_selector = PeerSelector::new(vec![peer_info], PeerStrategy::default(), None);
-        let sync_dag_store = SyncDagStore::create_for_testing()?;
+        let sync_dag_store = Arc::new(SyncDagStore::create_for_testing()?);
         Ok(Self::new_inner(
             peer_id,
             chain,
@@ -206,7 +208,7 @@ impl SyncNodeMocker {
         let peer_id = PeerId::random();
         let peer_info = PeerInfo::new(peer_id.clone(), chain.chain_info(), vec![], vec![], None);
         let peer_selector = PeerSelector::new(vec![peer_info], PeerStrategy::default(), None);
-        let sync_dag_store = SyncDagStore::create_for_testing()?;
+        let sync_dag_store = Arc::new(SyncDagStore::create_for_testing()?);
         Ok(Self::new_inner(
             peer_id,
             chain,
@@ -223,7 +225,7 @@ impl SyncNodeMocker {
         delay_milliseconds: u64,
         random_error_percent: u32,
         peer_selector: PeerSelector,
-        sync_dag_store: SyncDagStore,
+        sync_dag_store: Arc<SyncDagStore>,
     ) -> Self {
         Self::new_inner(
             peer_id,
@@ -241,7 +243,7 @@ impl SyncNodeMocker {
         error_strategy: ErrorStrategy,
         random_error_percent: u32,
         peer_selector: PeerSelector,
-        sync_dag_store: SyncDagStore,
+        sync_dag_store: Arc<SyncDagStore>,
     ) -> Self {
         Self {
             peer_id: peer_id.clone(),
diff --git a/sync/src/tasks/mod.rs b/sync/src/tasks/mod.rs
index 48abe6d18d..51a4cf844b 100644
--- a/sync/src/tasks/mod.rs
+++ b/sync/src/tasks/mod.rs
@@ -622,7 +622,7 @@ pub fn full_sync_task<H, A, F, N>(
     sync_metrics: Option<SyncMetrics>,
     vm_metrics: Option<VMMetrics>,
     dag: BlockDAG,
-    sync_dag_store: SyncDagStore,
+    sync_dag_store: Arc<SyncDagStore>,
 ) -> Result<(
     BoxFuture<'static, Result<BlockChain, TaskError>>,
     TaskHandle,
diff --git a/sync/src/tasks/tests.rs b/sync/src/tasks/tests.rs
index fee80c643f..797d0a7095 100644
--- a/sync/src/tasks/tests.rs
+++ b/sync/src/tasks/tests.rs
@@ -54,7 +54,7 @@ which is no longer suitable for the dag"]
 pub async fn test_failed_block() -> Result<()> {
     let net = ChainNetwork::new_builtin(BuiltinNetworkID::Halley);
     let (storage, chain_info, _, dag) = Genesis::init_storage_for_test(&net)?;
-    let sync_dag_store = SyncDagStore::create_for_testing()?;
+    let sync_dag_store = Arc::new(SyncDagStore::create_for_testing()?);
 
     let chain = BlockChain::new(
         net.time_service(),
@@ -917,7 +917,7 @@ async fn test_sync_target() {
         300,
         0,
         peer_selector,
-        SyncDagStore::create_for_testing().expect("failed to create the sync dag store"),
+        Arc::new(SyncDagStore::create_for_testing().expect("failed to create the sync dag store")),
     ));
     let full_target = node2
         .get_best_target(genesis_chain_info.total_difficulty())