feat(console): add scheduled time per task

console-api/proto/common.proto

@@ -180,7 +180,7 @@ message PollStats {
     // all polls. Note that this includes only polls that have completed and is
     // not reflecting any inprogress polls. Subtracting `busy_time` from the
     // total lifetime of the polled object results in the amount of time it
-    // has spent *waiting* to be polled.
+    // has spent *waiting* to be polled (including `scheduled_time`).
     google.protobuf.Duration busy_time = 6;
 }
 

console-api/proto/tasks.proto

@@ -130,6 +130,13 @@ message Stats {
     common.PollStats poll_stats = 7;
     // The total number of times this task has woken itself.
     uint64 self_wakes = 8;
+    // The total duration this task was scheduled prior to being polled, summed
+    // across all poll cycles. Note that this includes only polls that have
+    // started and is not reflecting any scheduled state where the task hasn't
+    // yet been polled. Subtracting both `busy_time` and `scheduled_time` from the
+    // total lifetime of the polled object results in the amount of time it spent
+    // unable to progress because it was waiting on some resource.
+    google.protobuf.Duration scheduled_time = 9;
 }
 
 

console-api/src/generated/rs.tokio.console.common.rs

@@ -256,7 +256,7 @@ pub struct PollStats {
     /// all polls. Note that this includes only polls that have completed and is
     /// not reflecting any inprogress polls. Subtracting `busy_time` from the
     /// total lifetime of the polled object results in the amount of time it
-    /// has spent *waiting* to be polled.
+    /// has spent *waiting* to be polled (including `scheduled_time`).
     #[prost(message, optional, tag="6")]
     pub busy_time: ::core::option::Option<::prost_types::Duration>,
 }

console-api/src/generated/rs.tokio.console.tasks.rs

@@ -167,6 +167,14 @@ pub struct Stats {
     /// The total number of times this task has woken itself.
     #[prost(uint64, tag="8")]
     pub self_wakes: u64,
+    /// The total duration this task was scheduled prior to being polled, summed
+    /// across all poll cycles. Note that this includes only polls that have
+    /// started and is not reflecting any scheduled state where the task hasn't
+    /// yet been polled. Subtracting both `busy_time` and `scheduled_time` from the
+    /// total lifetime of the polled object results in the amount of time it spent
+    /// unable to progress because it was waiting on some resource.
+    #[prost(message, optional, tag="9")]
+    pub scheduled_time: ::core::option::Option<::prost_types::Duration>,
 }
 #[derive(Clone, PartialEq, ::prost::Message)]
 pub struct DurationHistogram {

console-subscriber/examples/long_scheduled.rs

@@ -0,0 +1,78 @@
+//! Long scheduled time
+//!
+//! This example shows an application with a task that has an excessive
+//! time between being woken and being polled.
+//!
+//! It consists of a channel where a sender task sends a message
+//! through the channel and then immediately does a lot of work
+//! (simulated in this case by a call to `std::thread::sleep`).
+//!
+//! As soon as the sender task calls `send()` the receiver task gets
+//! woken, but because there's only a single worker thread, it doesn't
+//! get polled until after the sender task has finished "working" and
+//! yields (via `tokio::time::sleep`).
+//!
+//! In the console, this is visible in the `rx` task, which has very
+//! high scheduled times - in the detail screen you will see that around
+//! it is scheduled around 98% of the time. The `tx` task, on the other
+//! hand, is busy most of the time.
+use std::time::Duration;
+
+use console_subscriber::ConsoleLayer;
+use tokio::{sync::mpsc, task};
+use tracing::info;
+
+#[tokio::main(flavor = "multi_thread", worker_threads = 1)]
+async fn main() -> Result<(), Box<dyn std::error::Error>> {
+    ConsoleLayer::builder()
+        .with_default_env()
+        .publish_interval(Duration::from_millis(100))
+        .init();
+
+    let (tx, rx) = mpsc::channel::<u32>(1);
+    let count = 10000;
+
+    let jh_rx = task::Builder::new()
+        .name("rx")
+        .spawn(receiver(rx, count))
+        .unwrap();
+    let jh_tx = task::Builder::new()
+        .name("tx")
+        .spawn(sender(tx, count))
+        .unwrap();
+
+    let res_tx = jh_tx.await;
+    let res_rx = jh_rx.await;
+    info!(
+        "main: Joined sender: {:?} and receiver: {:?}",
+        res_tx, res_rx,
+    );
+
+    tokio::time::sleep(Duration::from_millis(200)).await;
+
+    Ok(())
+}
+
+async fn sender(tx: mpsc::Sender<u32>, count: u32) {
+    info!("tx: started");
+
+    for idx in 0..count {
+        let msg: u32 = idx;
+        let res = tx.send(msg).await;
+        info!("tx: sent msg '{}' result: {:?}", msg, res);
+
+        std::thread::sleep(Duration::from_millis(5000));
+        info!("tx: work done");
+
+        tokio::time::sleep(Duration::from_millis(100)).await;
+    }
+}
+
+async fn receiver(mut rx: mpsc::Receiver<u32>, count: u32) {
+    info!("rx: started");
+
+    for _ in 0..count {
+        let msg = rx.recv().await;
+        info!("rx: Received message: '{:?}'", msg);
+    }
+}

console-subscriber/src/stats.rs

@@ -56,7 +56,7 @@ pub(crate) struct TaskStats {
     is_dropped: AtomicBool,
     // task stats
     pub(crate) created_at: Instant,
-    timestamps: Mutex<TaskTimestamps>,
+    dropped_at: Mutex<Option<Instant>>,
 
     // waker stats
     wakes: AtomicUsize,
@@ -100,12 +100,6 @@ pub(crate) struct ResourceStats {
     pub(crate) parent_id: Option<Id>,
 }
 
-#[derive(Debug, Default)]
-struct TaskTimestamps {
-    dropped_at: Option<Instant>,
-    last_wake: Option<Instant>,
-}
-
 #[derive(Debug, Default)]
 struct PollStats<H> {
     /// The number of polls in progress
@@ -118,9 +112,11 @@ struct PollStats<H> {
 #[derive(Debug, Default)]
 struct PollTimestamps<H> {
     first_poll: Option<Instant>,
+    last_wake: Option<Instant>,
     last_poll_started: Option<Instant>,
     last_poll_ended: Option<Instant>,
     busy_time: Duration,
+    scheduled_time: Duration,
     histogram: H,
 }
 
@@ -162,14 +158,16 @@ impl TaskStats {
             is_dirty: AtomicBool::new(true),
             is_dropped: AtomicBool::new(false),
             created_at,
-            timestamps: Mutex::new(TaskTimestamps::default()),
+            dropped_at: Mutex::new(None),
             poll_stats: PollStats {
                 timestamps: Mutex::new(PollTimestamps {
                     histogram: Histogram::new(poll_duration_max),
                     first_poll: None,
+                    last_wake: None,
                     last_poll_started: None,
                     last_poll_ended: None,
                     busy_time: Duration::new(0, 0),
+                    scheduled_time: Duration::new(0, 0),
                 }),
                 current_polls: AtomicUsize::new(0),
                 polls: AtomicUsize::new(0),
@@ -209,13 +207,14 @@ impl TaskStats {
     }
 
     fn wake(&self, at: Instant, self_wake: bool) {
-        let mut timestamps = self.timestamps.lock();
-        timestamps.last_wake = cmp::max(timestamps.last_wake, Some(at));
-        self.wakes.fetch_add(1, Release);
+        self.poll_stats.wake(at);
 
+        self.wakes.fetch_add(1, Release);
         if self_wake {
             self.wakes.fetch_add(1, Release);
         }
+
+        self.make_dirty();
     }
 
     pub(crate) fn start_poll(&self, at: Instant) {
@@ -235,8 +234,7 @@ impl TaskStats {
             return;
         }
 
-        let mut timestamps = self.timestamps.lock();
-        let _prev = timestamps.dropped_at.replace(dropped_at);
+        let _prev = self.dropped_at.lock().replace(dropped_at);
         debug_assert_eq!(_prev, None, "tried to drop a task twice; this is a bug!");
         self.make_dirty();
     }
@@ -257,16 +255,28 @@ impl ToProto for TaskStats {
 
     fn to_proto(&self, base_time: &TimeAnchor) -> Self::Output {
         let poll_stats = Some(self.poll_stats.to_proto(base_time));
-        let timestamps = self.timestamps.lock();
+        let timestamps = self.poll_stats.timestamps.lock();
         proto::tasks::Stats {
             poll_stats,
             created_at: Some(base_time.to_timestamp(self.created_at)),
-            dropped_at: timestamps.dropped_at.map(|at| base_time.to_timestamp(at)),
+            dropped_at: self.dropped_at.lock().map(|at| base_time.to_timestamp(at)),
             wakes: self.wakes.load(Acquire) as u64,
             waker_clones: self.waker_clones.load(Acquire) as u64,
             self_wakes: self.self_wakes.load(Acquire) as u64,
             waker_drops: self.waker_drops.load(Acquire) as u64,
             last_wake: timestamps.last_wake.map(|at| base_time.to_timestamp(at)),
+            scheduled_time: Some(
+                timestamps
+                    .scheduled_time
+                    .try_into()
+                    .unwrap_or_else(|error| {
+                        eprintln!(
+                            "failed to convert `scheduled_time` to protobuf duration: {}",
+                            error
+                        );
+                        Default::default()
+                    }),
+            ),
         }
     }
 }
@@ -287,7 +297,7 @@ impl DroppedAt for TaskStats {
         // avoid acquiring the lock if we know we haven't tried to drop this
         // thing yet
         if self.is_dropped.load(Acquire) {
-            return self.timestamps.lock().dropped_at;
+            return *self.dropped_at.lock();
         }
 
         None
@@ -466,18 +476,46 @@ impl ToProto for ResourceStats {
 // === impl PollStats ===
 
 impl<H: RecordPoll> PollStats<H> {
-    fn start_poll(&self, at: Instant) {
-        if self.current_polls.fetch_add(1, AcqRel) == 0 {
-            // We are starting the first poll
-            let mut timestamps = self.timestamps.lock();
-            if timestamps.first_poll.is_none() {
-                timestamps.first_poll = Some(at);
-            }
+    fn wake(&self, at: Instant) {
+        let mut timestamps = self.timestamps.lock();
+        timestamps.last_wake = cmp::max(timestamps.last_wake, Some(at));
+    }
 
-            timestamps.last_poll_started = Some(at);
+    fn start_poll(&self, at: Instant) {
+        if self.current_polls.fetch_add(1, AcqRel) > 0 {
+            return;
+        }
 
-            self.polls.fetch_add(1, Release);
+        // We are starting the first poll
+        let mut timestamps = self.timestamps.lock();
+        if timestamps.first_poll.is_none() {
+            timestamps.first_poll = Some(at);
         }
+
+        timestamps.last_poll_started = Some(at);
+
+        self.polls.fetch_add(1, Release);
+
+        // If the last poll ended after the last wake then it was likely
+        // a self-wake, so we measure from the end of the last poll instead.
+        // This also ensures that `busy_time` and `scheduled_time` don't overlap.
+        let scheduled = match std::cmp::max(timestamps.last_wake, timestamps.last_poll_ended) {
+            Some(scheduled) => scheduled,
+            None => return, // Async operations record polls, but not wakes
+        };
+
+        let elapsed = match at.checked_duration_since(scheduled) {
+            Some(elapsed) => elapsed,
+            None => {
+                eprintln!(
+                    "possible Instant clock skew detected: a poll's start timestamp \
+                    was before the wake time/last poll end timestamp\nwake = {:?}\n  start = {:?}",
+                    scheduled, at
+                );
+                return;
+            }
+        };
+        timestamps.scheduled_time += elapsed;
     }
 
     fn end_poll(&self, at: Instant) {
@@ -534,7 +572,7 @@ impl<H> ToProto for PollStats<H> {
                 .map(|at| base_time.to_timestamp(at)),
             busy_time: Some(timestamps.busy_time.try_into().unwrap_or_else(|error| {
                 eprintln!(
-                    "failed to convert busy time to protobuf duration: {}",
+                    "failed to convert `busy_time` to protobuf duration: {}",
                     error
                 );
                 Default::default()