spawn availability store and approval voting subsystems as blocking tasks (#2521)

* spawn availability store and approval voting subsystems as blocking tasks

* refactor

polkadot/node/overseer/src/lib.rs

@@ -1457,6 +1457,7 @@ where
 			all_subsystems.candidate_validation,
 			&metrics,
 			&mut seed,
+			TaskKind::Regular,
 		)?;
 
 		let candidate_backing_subsystem = spawn(
@@ -1466,6 +1467,7 @@ where
 			all_subsystems.candidate_backing,
 			&metrics,
 			&mut seed,
+			TaskKind::Regular,
 		)?;
 
 		let candidate_selection_subsystem = spawn(
@@ -1475,6 +1477,7 @@ where
 			all_subsystems.candidate_selection,
 			&metrics,
 			&mut seed,
+			TaskKind::Regular,
 		)?;
 
 		let statement_distribution_subsystem = spawn(
@@ -1484,6 +1487,7 @@ where
 			all_subsystems.statement_distribution,
 			&metrics,
 			&mut seed,
+			TaskKind::Regular,
 		)?;
 
 		let availability_distribution_subsystem = spawn(
@@ -1493,6 +1497,7 @@ where
 			all_subsystems.availability_distribution,
 			&metrics,
 			&mut seed,
+			TaskKind::Regular,
 		)?;
 
 		let availability_recovery_subsystem = spawn(
@@ -1502,6 +1507,7 @@ where
 			all_subsystems.availability_recovery,
 			&metrics,
 			&mut seed,
+			TaskKind::Regular,
 		)?;
 
 		let bitfield_signing_subsystem = spawn(
@@ -1511,6 +1517,7 @@ where
 			all_subsystems.bitfield_signing,
 			&metrics,
 			&mut seed,
+			TaskKind::Regular,
 		)?;
 
 		let bitfield_distribution_subsystem = spawn(
@@ -1520,6 +1527,7 @@ where
 			all_subsystems.bitfield_distribution,
 			&metrics,
 			&mut seed,
+			TaskKind::Regular,
 		)?;
 
 		let provisioner_subsystem = spawn(
@@ -1529,6 +1537,7 @@ where
 			all_subsystems.provisioner,
 			&metrics,
 			&mut seed,
+			TaskKind::Regular,
 		)?;
 
 		let pov_distribution_subsystem = spawn(
@@ -1538,6 +1547,7 @@ where
 			all_subsystems.pov_distribution,
 			&metrics,
 			&mut seed,
+			TaskKind::Regular,
 		)?;
 
 		let runtime_api_subsystem = spawn(
@@ -1547,6 +1557,7 @@ where
 			all_subsystems.runtime_api,
 			&metrics,
 			&mut seed,
+			TaskKind::Regular,
 		)?;
 
 		let availability_store_subsystem = spawn(
@@ -1556,6 +1567,7 @@ where
 			all_subsystems.availability_store,
 			&metrics,
 			&mut seed,
+			TaskKind::Blocking,
 		)?;
 
 		let network_bridge_subsystem = spawn(
@@ -1565,6 +1577,7 @@ where
 			all_subsystems.network_bridge,
 			&metrics,
 			&mut seed,
+			TaskKind::Regular,
 		)?;
 
 		let chain_api_subsystem = spawn(
@@ -1574,6 +1587,7 @@ where
 			all_subsystems.chain_api,
 			&metrics,
 			&mut seed,
+			TaskKind::Regular,
 		)?;
 
 		let collation_generation_subsystem = spawn(
@@ -1583,6 +1597,7 @@ where
 			all_subsystems.collation_generation,
 			&metrics,
 			&mut seed,
+			TaskKind::Regular,
 		)?;
 
 
@@ -1593,6 +1608,7 @@ where
 			all_subsystems.collator_protocol,
 			&metrics,
 			&mut seed,
+			TaskKind::Regular,
 		)?;
 
 		let approval_distribution_subsystem = spawn(
@@ -1602,6 +1618,7 @@ where
 			all_subsystems.approval_distribution,
 			&metrics,
 			&mut seed,
+			TaskKind::Regular,
 		)?;
 
 		let approval_voting_subsystem = spawn(
@@ -1611,6 +1628,7 @@ where
 			all_subsystems.approval_voting,
 			&metrics,
 			&mut seed,
+			TaskKind::Blocking,
 		)?;
 
 		let leaves = leaves
@@ -1972,6 +1990,11 @@ where
 	}
 }
 
+enum TaskKind {
+	Regular,
+	Blocking,
+}
+
 fn spawn<S: SpawnNamed, M: Send + 'static>(
 	spawner: &mut S,
 	futures: &mut FuturesUnordered<BoxFuture<'static, SubsystemResult<()>>>,
@@ -1979,6 +2002,7 @@ fn spawn<S: SpawnNamed, M: Send + 'static>(
 	s: impl Subsystem<OverseerSubsystemContext<M>>,
 	metrics: &Metrics,
 	seed: &mut u64,
+	task_kind: TaskKind,
 ) -> SubsystemResult<OverseenSubsystem<M>> {
 	let (to_tx, to_rx) = metered::channel(CHANNEL_CAPACITY, "subsystem_spawn");
 	let ctx = OverseerSubsystemContext::new(
@@ -2004,7 +2028,10 @@ fn spawn<S: SpawnNamed, M: Send + 'static>(
 		let _ = tx.send(());
 	});
 
-	spawner.spawn(name, fut);
+	match task_kind {
+		TaskKind::Regular => spawner.spawn(name, fut),
+		TaskKind::Blocking => spawner.spawn_blocking(name, fut),
+	}
 
 	futures.push(Box::pin(rx.map(|e| { tracing::warn!(err = ?e, "dropping error"); Ok(()) })));
 
@@ -2018,7 +2045,6 @@ fn spawn<S: SpawnNamed, M: Send + 'static>(
 	})
 }
 
-
 #[cfg(test)]
 mod tests {
 	use std::sync::atomic;