metrics: fix blocking_threads count (#6551)

tokio-rs · May 25, 2024 · 2890d0c · 2890d0c
1 parent 0a85a96
commit 2890d0c
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Showing 3 changed files with 13 additions and 2 deletions.
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]