perf: mine new blocks on blocking task (#7328)

crates/anvil/src/service.rs

@@ -18,7 +18,7 @@ use std::{
     sync::Arc,
     task::{Context, Poll},
 };
-use tokio::time::Interval;
+use tokio::{task::JoinHandle, time::Interval};
 
 /// The type that drives the blockchain's state
 ///
@@ -101,17 +101,13 @@ impl Future for NodeService {
     }
 }
 
-// The type of the future that mines a new block
-type BlockMiningFuture =
-    Pin<Box<dyn Future<Output = (MinedBlockOutcome, Arc<Backend>)> + Send + Sync>>;
-
 /// A type that exclusively mines one block at a time
 #[must_use = "streams do nothing unless polled"]
 struct BlockProducer {
     /// Holds the backend if no block is being mined
     idle_backend: Option<Arc<Backend>>,
     /// Single active future that mines a new block
-    block_mining: Option<BlockMiningFuture>,
+    block_mining: Option<JoinHandle<(MinedBlockOutcome, Arc<Backend>)>>,
     /// backlog of sets of transactions ready to be mined
     queued: VecDeque<Vec<Arc<PoolTransaction>>>,
 }
@@ -133,19 +129,33 @@ impl Stream for BlockProducer {
         if !pin.queued.is_empty() {
             if let Some(backend) = pin.idle_backend.take() {
                 let transactions = pin.queued.pop_front().expect("not empty; qed");
-                pin.block_mining = Some(Box::pin(async move {
-                    trace!(target: "miner", "creating new block");
-                    let block = backend.mine_block(transactions).await;
-                    trace!(target: "miner", "created new block: {}", block.block_number);
-                    (block, backend)
-                }));
+
+                // we spawn this on as blocking task because in this can be blocking for a while in
+                // forking mode, because of all the rpc calls to fetch the required state
+                let handle = tokio::runtime::Handle::current();
+                let mining = tokio::task::spawn_blocking(move || {
+                    handle.block_on(async move {
+                        trace!(target: "miner", "creating new block");
+                        let block = backend.mine_block(transactions).await;
+                        trace!(target: "miner", "created new block: {}", block.block_number);
+                        (block, backend)
+                    })
+                });
+                pin.block_mining = Some(mining);
             }
         }
 
         if let Some(mut mining) = pin.block_mining.take() {
-            if let Poll::Ready((outcome, backend)) = mining.poll_unpin(cx) {
-                pin.idle_backend = Some(backend);
-                return Poll::Ready(Some(outcome))
+            if let Poll::Ready(res) = mining.poll_unpin(cx) {
+                return match res {
+                    Ok((outcome, backend)) => {
+                        pin.idle_backend = Some(backend);
+                        Poll::Ready(Some(outcome))
+                    }
+                    Err(err) => {
+                        panic!("miner task failed: {}", err);
+                    }
+                }
             } else {
                 pin.block_mining = Some(mining)
             }