metrics: fix blocking_threads count (#6551)

conradludgate · web-flow · commit 2890d0c3db4f · 2024-05-25T21:49:17.000Z
diff --git a/tokio/src/runtime/scheduler/multi_thread/handle/metrics.rs b/tokio/src/runtime/scheduler/multi_thread/handle/metrics.rs
@@ -8,7 +8,10 @@ impl Handle {
     }
 
     pub(crate) fn num_blocking_threads(&self) -> usize {
-        self.blocking_spawner.num_threads()
+        // workers are currently spawned using spawn_blocking
+        self.blocking_spawner
+            .num_threads()
+            .saturating_sub(self.num_workers())
     }
 
     pub(crate) fn num_idle_blocking_threads(&self) -> usize {
diff --git a/tokio/src/runtime/scheduler/multi_thread_alt/handle/metrics.rs b/tokio/src/runtime/scheduler/multi_thread_alt/handle/metrics.rs
@@ -8,7 +8,10 @@ impl Handle {
     }
 
     pub(crate) fn num_blocking_threads(&self) -> usize {
-        self.blocking_spawner.num_threads()
+        // workers are currently spawned using spawn_blocking
+        self.blocking_spawner
+            .num_threads()
+            .saturating_sub(self.num_workers())
     }
 
     pub(crate) fn num_idle_blocking_threads(&self) -> usize {
diff --git a/tokio/tests/rt_metrics.rs b/tokio/tests/rt_metrics.rs
@@ -31,6 +31,11 @@ fn num_blocking_threads() {
     assert_eq!(0, rt.metrics().num_blocking_threads());
     let _ = rt.block_on(rt.spawn_blocking(move || {}));
     assert_eq!(1, rt.metrics().num_blocking_threads());
+
+    let rt = threaded();
+    assert_eq!(0, rt.metrics().num_blocking_threads());
+    let _ = rt.block_on(rt.spawn_blocking(move || {}));
+    assert_eq!(1, rt.metrics().num_blocking_threads());
 }
 
 #[test]

Original file line number	Diff line number	Diff line change
`@@ -8,7 +8,10 @@ impl Handle {`
`8`	`8`	`}`
`9`	`9`
`10`	`10`	`pub(crate) fn num_blocking_threads(&self) -> usize {`
`11`		`- self.blocking_spawner.num_threads()`
	`11`	`+ // workers are currently spawned using spawn_blocking`
	`12`	`+ self.blocking_spawner`
	`13`	`+ .num_threads()`
	`14`	`+ .saturating_sub(self.num_workers())`
`12`	`15`	`}`
`13`	`16`
`14`	`17`	`pub(crate) fn num_idle_blocking_threads(&self) -> usize {`