Reduce signal channel sizes and more logging on approval-voting (#2751)

* reduce signal channel capacity

* more tracing for approval-voting

polkadot/node/core/approval-voting/src/import.rs

@@ -495,9 +495,25 @@ async fn imported_block_info(
 		}
 	};
 
+	tracing::trace!(
+		target: LOG_TARGET,
+		n_assignments = assignments.len(),
+		"Produced assignments"
+	);
+
 	let force_approve =
 		block_header.digest.convert_first(|l| match ConsensusLog::from_digest_item(l) {
-			Ok(Some(ConsensusLog::ForceApprove(num))) if num < block_header.number => Some(num),
+			Ok(Some(ConsensusLog::ForceApprove(num))) if num < block_header.number => {
+				tracing::trace!(
+					target: LOG_TARGET,
+					?block_hash,
+					current_number = block_header.number,
+					approved_number = num,
+					"Force-approving based on header digest"
+				);
+
+				Some(num)
+			}
 			Ok(Some(_)) => None,
 			Ok(None) => None,
 			Err(err) => {
@@ -635,6 +651,12 @@ pub(crate) async fn handle_new_head(
 		imported_blocks_and_info
 	};
 
+	tracing::trace!(
+		target: LOG_TARGET,
+		imported_blocks = imported_blocks_and_info.len(),
+		"Inserting imported blocks into database"
+	);
+
 	for (block_hash, block_header, imported_block_info) in imported_blocks_and_info {
 		let ImportedBlockInfo {
 			included_candidates,
@@ -708,10 +730,24 @@ pub(crate) async fn handle_new_head(
 		};
 
 		if let Some(up_to) = force_approve {
+			tracing::debug!(
+				target: LOG_TARGET,
+				?block_hash,
+				up_to,
+				"Enacting force-approve",
+			);
+
 			approval_db::v1::force_approve(db_writer, block_hash, up_to)
 				.map_err(|e| SubsystemError::with_origin("approval-voting", e))?;
 		}
 
+		tracing::trace!(
+			target: LOG_TARGET,
+			?block_hash,
+			block_number = block_header.number,
+			"Writing BlockEntry",
+		);
+
 		let candidate_entries = approval_db::v1::add_block_entry(
 			db_writer,
 			block_entry,
@@ -747,6 +783,13 @@ pub(crate) async fn handle_new_head(
 		);
 	}
 
+	tracing::trace!(
+		target: LOG_TARGET,
+		head = ?head,
+		chain_length = approval_meta.len(),
+		"Informing distribution of newly imported chain",
+	);
+
 	ctx.send_message(ApprovalDistributionMessage::NewBlocks(approval_meta).into()).await;
 
 	Ok(imported_candidates)

polkadot/node/overseer/src/lib.rs

@@ -96,6 +96,9 @@ use polkadot_node_primitives::SpawnNamed;
 
 // A capacity of bounded channels inside the overseer.
 const CHANNEL_CAPACITY: usize = 1024;
+// The capacity of signal channels to subsystems.
+const SIGNAL_CHANNEL_CAPACITY: usize = 64;
+
 // A graceful `Overseer` teardown time delay.
 const STOP_DELAY: u64 = 1;
 // Target for logs.
@@ -2629,7 +2632,7 @@ fn spawn<S: SpawnNamed, M: Send + 'static>(
 	futures: &mut FuturesUnordered<BoxFuture<'static, SubsystemResult<()>>>,
 	task_kind: TaskKind,
 ) -> SubsystemResult<OverseenSubsystem<M>> {
-	let (signal_tx, signal_rx) = metered::channel(CHANNEL_CAPACITY);
+	let (signal_tx, signal_rx) = metered::channel(SIGNAL_CHANNEL_CAPACITY);
 	let ctx = OverseerSubsystemContext::new(
 		signal_rx,
 		message_rx,