Avoid serving validator endpoints while the node is far behind syncing head (sigp#7962)

jimmygchen · web-flow · commit 438fb65d4500 · 2025-08-29T03:01:40.000Z
A performance issue was discovered when devnet-3 was under non-finality - some of the lighthouse nodes are "stuck" with syncing because of handling proposer duties HTTP requests. These validator requests are higher priority than Status processing, and if they are taking a long time to process, the node won't be able to progress. What's worse is - under long period of non finality, the proposer duties calculation function tries to do state advance for a large number of [slots](https://github.com/sigp/lighthouse/blob/d545ddcbc7d97b24b5c15012d1a5f9a1dae90b2a/beacon_node/beacon_chain/src/beacon_proposer_cache.rs#L183) here, causing the node to spend all its CPU time on a task that doesn't really help, e.g. the computed duties aren't useful if the node is 20000 slots behind. To solve this issue, we use the `not_while_syncing` filter to prevent serving these requests, until the node is synced. This should allow the node to focus on sync under non-finality situations.
diff --git a/beacon_node/http_api/src/lib.rs b/beacon_node/http_api/src/lib.rs
@@ -457,7 +457,7 @@ pub fn serve<T: BeaconChainTypes>(
                 move |network_globals: Arc<NetworkGlobals<T::EthSpec>>,
                       chain: Arc<BeaconChain<T>>| async move {
                     match *network_globals.sync_state.read() {
-                        SyncState::SyncingFinalized { .. } => {
+                        SyncState::SyncingFinalized { .. } | SyncState::SyncingHead { .. } => {
                             let head_slot = chain.canonical_head.cached_head().head_slot();
 
                             let current_slot =
@@ -479,9 +479,7 @@ pub fn serve<T: BeaconChainTypes>(
                                 )))
                             }
                         }
-                        SyncState::SyncingHead { .. }
-                        | SyncState::SyncTransition
-                        | SyncState::BackFillSyncing { .. } => Ok(()),
+                        SyncState::SyncTransition | SyncState::BackFillSyncing { .. } => Ok(()),
                         SyncState::Synced => Ok(()),
                         SyncState::Stalled => Ok(()),
                     }

Original file line number	Diff line number	Diff line change
`@@ -457,7 +457,7 @@ pub fn serve<T: BeaconChainTypes>(`
`457`	`457`	`move \|network_globals: Arc<NetworkGlobals<T::EthSpec>>,`
`458`	`458`	`chain: Arc<BeaconChain<T>>\| async move {`
`459`	`459`	`match *network_globals.sync_state.read() {`
`460`		`- SyncState::SyncingFinalized { .. } => {`
	`460`	`+ SyncState::SyncingFinalized { .. } \| SyncState::SyncingHead { .. } => {`
`461`	`461`	`let head_slot = chain.canonical_head.cached_head().head_slot();`
`462`	`462`
`463`	`463`	`let current_slot =`
`@@ -479,9 +479,7 @@ pub fn serve<T: BeaconChainTypes>(`
`479`	`479`	`)))`
`480`	`480`	`}`
`481`	`481`	`}`
`482`		`- SyncState::SyncingHead { .. }`
`483`		`- \| SyncState::SyncTransition`
`484`		`- \| SyncState::BackFillSyncing { .. } => Ok(()),`
	`482`	`+ SyncState::SyncTransition \| SyncState::BackFillSyncing { .. } => Ok(()),`
`485`	`483`	`SyncState::Synced => Ok(()),`
`486`	`484`	`SyncState::Stalled => Ok(()),`
`487`	`485`	`}`