Demonstrate leaked threads

If I run

  cargo t  -p neard --test run_nodes -- run_nodes_1_2_1 --nocapture --test-threads 1

I see

  will drop PeerManagerActor

but not

  did drop PeerManagerActor

This means that the corresponding thread is being abruptly terminated.

chain/network/src/peer.rs

@@ -184,6 +184,14 @@ pub struct Peer {
     peer_counter: Arc<AtomicUsize>,
 }
 
+impl Drop for Peer {
+    fn drop(&mut self) {
+        eprintln!("will drop Peer");
+        std::thread::sleep(std::time::Duration::from_millis(250));
+        eprintln!("did drop Peer");
+    }
+}
+
 impl Peer {
     pub fn new(
         node_info: PeerInfo,

chain/network/src/peer_manager.rs

@@ -154,6 +154,14 @@ pub struct PeerManagerActor {
     scheduled_routing_table_update: bool,
 }
 
+impl Drop for PeerManagerActor {
+    fn drop(&mut self) {
+        eprintln!("will drop PeerManagerActor");
+        std::thread::sleep(std::time::Duration::from_millis(250));
+        eprintln!("did drop PeerManagerActor");
+    }
+}
+
 impl PeerManagerActor {
     pub fn new(
         store: Arc<Store>,