rt: Allow concurrent `block_on`'s with basic_scheduler (#2804)

1 files changed, 32 insertions, 0 deletions

diff --git a/tokio/tests/rt_common.rs b/tokio/tests/rt_common.rs
index 35e2ea81..a8968be1 100644
--- a/tokio/tests/rt_common.rs
+++ b/tokio/tests/rt_common.rs
@@ -575,6 +575,38 @@ rt_test! {
     }
 
     #[test]
+    fn always_active_parker() {
+        // This test it to show that we will always have
+        // an active parker even if we call block_on concurrently
+
+        let rt = rt();
+        let rt2 = rt.clone();
+
+        let (tx1, rx1) = oneshot::channel();
+        let (tx2, rx2) = oneshot::channel();
+
+        let jh1 = thread::spawn(move || {
+                rt.block_on(async move {
+                    rx2.await.unwrap();
+                    time::delay_for(Duration::from_millis(5)).await;
+                    tx1.send(()).unwrap();
+                });
+        });
+
+        let jh2 = thread::spawn(move || {
+            rt2.block_on(async move {
+                tx2.send(()).unwrap();
+                time::delay_for(Duration::from_millis(5)).await;
+                rx1.await.unwrap();
+                time::delay_for(Duration::from_millis(5)).await;
+            });
+        });
+
+        jh1.join().unwrap();
+        jh2.join().unwrap();
+    }
+
+    #[test]
     // IOCP requires setting the "max thread" concurrency value. The sane,
     // default, is to set this to the number of cores. Threads that poll I/O
     // become associated with the IOCP handle. Once those threads sleep for any