Weigh gilknocker Prometheus metric by duration (dask#8558)

distributed/dashboard/components/scheduler.py

@@ -3911,19 +3911,20 @@ def __init__(self, scheduler, **kwargs):
     @log_errors
     def update(self):
         s = self.scheduler
-        monitor_gil = s.monitor.monitor_gil_contention
 
         self.data["values"] = [
             s._tick_interval_observed,
             self.gil_contention_scheduler,
             sum(w.metrics["event_loop_interval"] for w in s.workers.values())
             / (len(s.workers) or 1),
             self.gil_contention_workers,
-        ][:: 1 if monitor_gil else 2]
+        ][:: 1 if s.monitor.monitor_gil_contention else 2]
 
         # Format event loop as time and GIL (if configured) as %
         self.data["text"] = [
-            f"{x * 100:.1f}%" if i % 2 and monitor_gil else format_time(x)
+            f"{x * 100:.1f}%"
+            if i % 2 and s.monitor.monitor_gil_contention
+            else format_time(x)
             for i, x in enumerate(self.data["values"])
         ]
         update(self.source, self.data)

distributed/http/scheduler/prometheus/core.py

@@ -56,7 +56,8 @@ def collect(self) -> Iterator[GaugeMetricFamily | CounterMetricFamily]:
             yield CounterMetricFamily(
                 self.build_name("gil_contention"),
                 "GIL contention metric",
-                value=self.server.monitor._cumulative_gil_contention,
+                value=self.server.monitor.cumulative_gil_contention,
+                unit="seconds",
             )
 
         yield CounterMetricFamily(

distributed/http/scheduler/tests/test_scheduler_http.py

@@ -132,7 +132,7 @@ async def test_prometheus(c, s, a, b):
     except ImportError:
         pass  # pragma: nocover
     else:
-        expected_metrics.add("dask_scheduler_gil_contention")
+        expected_metrics.add("dask_scheduler_gil_contention_seconds")
 
     assert set(active_metrics.keys()) == expected_metrics
     assert active_metrics["dask_scheduler_clients"].samples[0].value == 1.0

distributed/http/tests/test_core.py

@@ -73,8 +73,8 @@ async def test_prometheus_api_doc(c, s, a, _):
         gil_metrics = set()  # Already in worker_metrics
     except ImportError:
         gil_metrics = {
-            "dask_scheduler_gil_contention_total",
-            "dask_worker_gil_contention_total",
+            "dask_scheduler_gil_contention_seconds_total",
+            "dask_worker_gil_contention_seconds_total",
         }
 
     implemented = scheduler_metrics | worker_metrics | crick_metrics | gil_metrics

distributed/http/worker/prometheus/core.py

@@ -63,7 +63,8 @@ def collect(self) -> Iterator[Metric]:
             yield CounterMetricFamily(
                 self.build_name("gil_contention"),
                 "GIL contention metric",
-                value=self.server.monitor._cumulative_gil_contention,
+                value=self.server.monitor.cumulative_gil_contention,
+                unit="seconds",
             )
 
         yield GaugeMetricFamily(

distributed/http/worker/tests/test_worker_http.py

@@ -59,7 +59,7 @@ async def test_prometheus(c, s, a):
     except ImportError:
         pass  # pragma: nocover
     else:
-        expected_metrics.add("dask_worker_gil_contention_total")
+        expected_metrics.add("dask_worker_gil_contention_seconds_total")
 
     try:
         import crick  # noqa: F401

distributed/system_monitor.py

@@ -31,7 +31,7 @@ class SystemMonitor:
     _last_host_cpu_counters: Any  # dynamically-defined psutil namedtuple
     _last_gil_contention: float  # 0-1 value
 
-    _cumulative_gil_contention: float
+    cumulative_gil_contention: float
 
     gpu_name: str | None
     gpu_memory_total: int
@@ -114,12 +114,11 @@ def __init__(
                 self.monitor_gil_contention = False
             else:
                 self.quantities["gil_contention"] = deque(maxlen=maxlen)
-                self._cumulative_gil_contention = 0.0
+                self.cumulative_gil_contention = 0.0
                 raw_interval = dask.config.get(
                     "distributed.admin.system-monitor.gil.interval",
                 )
-                interval = parse_timedelta(raw_interval, default="us") * 1e6
-
+                interval = parse_timedelta(raw_interval) * 1e6
                 self._gilknocker = KnockKnock(polling_interval_micros=int(interval))
                 self._gilknocker.start()
 
@@ -197,10 +196,10 @@ def update(self) -> dict[str, Any]:
             self._last_host_cpu_counters = host_cpu
 
         if self.monitor_gil_contention:
-            self._last_gil_contention = self._gilknocker.contention_metric
-            self._cumulative_gil_contention += self._last_gil_contention
-            result["gil_contention"] = self._last_gil_contention
+            gil_contention = self._gilknocker.contention_metric
             self._gilknocker.reset_contention_metric()
+            result["gil_contention"] = self._last_gil_contention = gil_contention
+            self.cumulative_gil_contention += duration * gil_contention
 
         # Note: WINDOWS constant doesn't work with `mypy --platform win32`
         if sys.platform != "win32":

docs/source/prometheus.rst

@@ -26,9 +26,11 @@ dask_scheduler_clients
     Number of clients connected
 dask_scheduler_desired_workers
     Number of workers scheduler needs for task graph
-dask_scheduler_gil_contention_total
-    Value representing cumulative total of GIL contention,
-    in the form of summed percentages.
+dask_scheduler_gil_contention_seconds_total
+    Value representing cumulative total of *potential* GIL contention,
+    in the form of cumulative seconds during which any thread held the GIL locked.
+    Other threads may or may not have been actually trying to acquire the GIL in the
+    meantime.
 
     .. note::
        Requires ``gilknocker`` to be installed, and 
@@ -128,9 +130,11 @@ dask_worker_tasks
     Number of tasks at worker
 dask_worker_threads
     Number of worker threads
-dask_worker_gil_contention_total
-    Value representing cumulative total GIL contention on worker,
-    in the form of summed percentages.
+dask_worker_gil_contention_seconds_total
+    Value representing cumulative total of *potential* GIL contention,
+    in the form of cumulative seconds during which any thread held the GIL locked.
+    Other threads may or may not have been actually trying to acquire the GIL in the
+    meantime.
 
     .. note::
        Requires ``gilknocker`` to be installed, and