Add timeouts to metric SDK

CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased](https://github.com/open-telemetry/opentelemetry-python/compare/v1.11.1-0.30b1...HEAD)
 
+- Add timeouts to metric SDK
+  ([#2653](https://github.com/open-telemetry/opentelemetry-python/pull/2653))
 - Add variadic arguments to metric exporter/reader interfaces
   ([#2654](https://github.com/open-telemetry/opentelemetry-python/pull/2654))
 - Move Metrics API behind internal package

exporter/opentelemetry-exporter-otlp-proto-grpc/src/opentelemetry/exporter/otlp/proto/grpc/_metric_exporter/__init__.py

@@ -169,9 +169,13 @@ def _translate_data(
         )
 
     def export(
-        self, metrics: Sequence[Metric], *args, **kwargs
+        self,
+        metrics: Sequence[Metric],
+        timeout_millis: float = 10_000,
+        **kwargs,
     ) -> MetricExportResult:
+        # TODO(#2663): OTLPExporterMixin should pass timeout to gRPC
         return self._export(metrics)
 
-    def shutdown(self, *args, **kwargs):
+    def shutdown(self, timeout_millis: float = 30_000, **kwargs) -> None:
         pass

exporter/opentelemetry-exporter-prometheus/src/opentelemetry/exporter/prometheus/__init__.py

@@ -111,15 +111,17 @@ def __init__(self, prefix: str = "") -> None:
         self._collector._callback = self.collect
 
     def _receive_metrics(
-        self, metrics: Iterable[Metric], *args, **kwargs
+        self,
+        metrics: Iterable[Metric],
+        timeout_millis: float = 10_000,
+        **kwargs,
     ) -> None:
         if metrics is None:
             return
         self._collector.add_metrics_data(metrics)
 
-    def shutdown(self, *args, **kwargs) -> bool:
+    def shutdown(self, timeout_millis: float = 30_000, **kwargs) -> None:
         REGISTRY.unregister(self._collector)
-        return True
 
 
 class _CustomCollector:

opentelemetry-sdk/src/opentelemetry/sdk/_metrics/_internal/__init__.py

@@ -48,6 +48,7 @@
 from opentelemetry.sdk.resources import Resource
 from opentelemetry.sdk.util.instrumentation import InstrumentationScope
 from opentelemetry.util._once import Once
+from opentelemetry.util._time import _time_ns
 
 _logger = getLogger(__name__)
 
@@ -369,16 +370,20 @@ def __init__(
         self._shutdown_once = Once()
         self._shutdown = False
 
-    def force_flush(self) -> bool:
-
-        # FIXME implement a timeout
+    def force_flush(self, timeout_millis: float = 10_000) -> bool:
+        deadline_ns = _time_ns() + timeout_millis * 10**6
 
         for metric_reader in self._sdk_config.metric_readers:
-            metric_reader.collect()
+            current_ts = _time_ns()
+            if current_ts >= deadline_ns:
+                raise Exception("Timed out while flushing metric readers")
+            metric_reader.collect(
+                timeout_millis=(deadline_ns - current_ts) / 10**6
+            )
         return True
 
-    def shutdown(self):
-        # FIXME implement a timeout
+    def shutdown(self, timeout_millis: float = 30_000):
+        deadline_ns = _time_ns() + timeout_millis * 10**6
 
         def _shutdown():
             self._shutdown = True
@@ -392,8 +397,15 @@ def _shutdown():
         metric_reader_error = {}
 
         for metric_reader in self._sdk_config.metric_readers:
+            current_ts = _time_ns()
             try:
-                metric_reader.shutdown()
+                if current_ts >= deadline_ns:
+                    raise Exception(
+                        "Didn't get to execute, deadline already exceeded"
+                    )
+                metric_reader.shutdown(
+                    timeout_millis=(deadline_ns - current_ts) / 10**6
+                )
 
             # pylint: disable=broad-except
             except Exception as error:

opentelemetry-sdk/src/opentelemetry/sdk/_metrics/_internal/export/__init__.py

@@ -31,6 +31,7 @@
 from opentelemetry.sdk._metrics.metric_reader import MetricReader
 from opentelemetry.sdk._metrics.point import AggregationTemporality, Metric
 from opentelemetry.util._once import Once
+from opentelemetry.util._time import _time_ns
 
 _logger = logging.getLogger(__name__)
 
@@ -53,8 +54,11 @@ class MetricExporter(ABC):
 
     @abstractmethod
     def export(
-        self, metrics: Sequence[Metric], *args, **kwargs
-    ) -> "MetricExportResult":
+        self,
+        metrics: Sequence[Metric],
+        timeout_millis: float = 10_000,
+        **kwargs,
+    ) -> MetricExportResult:
         """Exports a batch of telemetry data.
 
         Args:
@@ -65,7 +69,7 @@ def export(
         """
 
     @abstractmethod
-    def shutdown(self, *args, **kwargs) -> None:
+    def shutdown(self, timeout_millis: float = 30_000, **kwargs) -> None:
         """Shuts down the exporter.
 
         Called when the SDK is shut down.
@@ -90,14 +94,17 @@ def __init__(
         self.formatter = formatter
 
     def export(
-        self, metrics: Sequence[Metric], *args, **kwargs
+        self,
+        metrics: Sequence[Metric],
+        timeout_millis: float = 10_000,
+        **kwargs,
     ) -> MetricExportResult:
         for metric in metrics:
             self.out.write(self.formatter(metric))
         self.out.flush()
         return MetricExportResult.SUCCESS
 
-    def shutdown(self, *args, **kwargs) -> None:
+    def shutdown(self, timeout_millis: float = 30_000, **kwargs) -> None:
         pass
 
 
@@ -127,11 +134,16 @@ def get_metrics(self) -> List[Metric]:
             self._metrics = []
         return metrics
 
-    def _receive_metrics(self, metrics: Iterable[Metric], *args, **kwargs):
+    def _receive_metrics(
+        self,
+        metrics: Iterable[Metric],
+        timeout_millis: float = 10_000,
+        **kwargs,
+    ) -> None:
         with self._lock:
             self._metrics = list(metrics)
 
-    def shutdown(self, *args, **kwargs):
+    def shutdown(self, timeout_millis: float = 30_000, **kwargs) -> None:
         pass
 
 
@@ -193,23 +205,28 @@ def _at_fork_reinit(self):
     def _ticker(self) -> None:
         interval_secs = self._export_interval_millis / 1e3
         while not self._shutdown_event.wait(interval_secs):
-            self.collect()
+            self.collect(timeout_millis=self._export_timeout_millis)
         # one last collection below before shutting down completely
-        self.collect()
+        self.collect(timeout_millis=self._export_interval_millis)
 
     def _receive_metrics(
-        self, metrics: Iterable[Metric], *args, **kwargs
+        self,
+        metrics: Iterable[Metric],
+        timeout_millis: float = 10_000,
+        **kwargs,
     ) -> None:
         if metrics is None:
             return
         token = attach(set_value(_SUPPRESS_INSTRUMENTATION_KEY, True))
         try:
-            self._exporter.export(metrics)
+            self._exporter.export(metrics, timeout_millis=timeout_millis)
         except Exception as e:  # pylint: disable=broad-except,invalid-name
             _logger.exception("Exception while exporting metrics %s", str(e))
         detach(token)
 
-    def shutdown(self, *args, **kwargs):
+    def shutdown(self, timeout_millis: float = 30_000, **kwargs) -> None:
+        deadline_ns = _time_ns() + timeout_millis * 10**6
+
         def _shutdown():
             self._shutdown = True
 
@@ -219,5 +236,5 @@ def _shutdown():
             return
 
         self._shutdown_event.set()
-        self._daemon_thread.join()
-        self._exporter.shutdown()
+        self._daemon_thread.join(timeout=(deadline_ns - _time_ns()) / 10**9)
+        self._exporter.shutdown(timeout=(deadline_ns - _time_ns()) / 10**6)

opentelemetry-sdk/src/opentelemetry/sdk/_metrics/_internal/metric_reader.py

@@ -138,7 +138,7 @@ def __init__(
         self._instrument_class_aggregation.update(preferred_aggregation or {})
 
     @final
-    def collect(self) -> None:
+    def collect(self, timeout_millis: float = 10_000) -> None:
         """Collects the metrics from the internal SDK state and
         invokes the `_receive_metrics` with the collection.
         """
@@ -148,7 +148,8 @@ def collect(self) -> None:
             )
             return
         self._receive_metrics(
-            self._collect(self, self._instrument_class_temporality)
+            self._collect(self, self._instrument_class_temporality),
+            timeout_millis=timeout_millis,
         )
 
     @final
@@ -162,11 +163,16 @@ def _set_collect_callback(
         self._collect = func
 
     @abstractmethod
-    def _receive_metrics(self, metrics: Iterable[Metric], *args, **kwargs):
+    def _receive_metrics(
+        self,
+        metrics: Iterable[Metric],
+        timeout_millis: float = 10_000,
+        **kwargs,
+    ) -> None:
         """Called by `MetricReader.collect` when it receives a batch of metrics"""
 
     @abstractmethod
-    def shutdown(self, *args, **kwargs):
+    def shutdown(self, timeout_millis: float = 30_000, **kwargs) -> None:
         """Shuts down the MetricReader. This method provides a way
         for the MetricReader to do any cleanup required. A metric reader can
         only be shutdown once, any subsequent calls are ignored and return

opentelemetry-sdk/tests/metrics/test_backward_compat.py

@@ -0,0 +1,89 @@
+# Copyright The OpenTelemetry Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+The purpose of this test is to test for backward compatibility with any user-implementable
+interfaces as they were originally defined. For example, changes to the MetricExporter ABC must
+be made in such a way that existing implementations (outside of this repo) continue to work
+when *called* by the SDK.
+
+This does not apply to classes which are not intended to be overriden by the user e.g.  Meter
+and PeriodicExportingMetricReader concrete class. Those may freely be modified in a
+backward-compatible way for *callers*.
+
+Ideally, we could use mypy for this as well, but SDK is not type checked atm.
+"""
+
+from typing import Iterable, Sequence
+from unittest import TestCase
+
+from opentelemetry.sdk._metrics import MeterProvider
+from opentelemetry.sdk._metrics.export import (
+    MetricExporter,
+    MetricExportResult,
+    PeriodicExportingMetricReader,
+)
+from opentelemetry.sdk._metrics.metric_reader import MetricReader
+from opentelemetry.sdk._metrics.point import Metric
+
+
+# Do not change these classes until after major version 1
+class OrigMetricExporter(MetricExporter):
+    def export(
+        self,
+        metrics: Sequence[Metric],
+        timeout_millis: float = 10_000,
+        **kwargs,
+    ) -> MetricExportResult:
+        pass
+
+    def shutdown(self, timeout_millis: float = 30_000, **kwargs) -> None:
+        pass
+
+
+class OrigMetricReader(MetricReader):
+    def _receive_metrics(
+        self,
+        metrics: Iterable[Metric],
+        timeout_millis: float = 10_000,
+        **kwargs,
+    ) -> None:
+        pass
+
+    def shutdown(self, timeout_millis: float = 30_000, **kwargs) -> None:
+        self.collect()
+
+
+class TestBackwardCompat(TestCase):
+    def test_metric_exporter(self):
+        exporter = OrigMetricExporter()
+        meter_provider = MeterProvider(
+            metric_readers=[PeriodicExportingMetricReader(exporter)]
+        )
+        # produce some data
+        meter_provider.get_meter("foo").create_counter("mycounter").add(12)
+        try:
+            meter_provider.shutdown()
+        except Exception:
+            self.fail()
+
+    def test_metric_reader(self):
+        reader = OrigMetricReader()
+        meter_provider = MeterProvider(metric_readers=[reader])
+        # produce some data
+        meter_provider.get_meter("foo").create_counter("mycounter").add(12)
+        try:
+            meter_provider.shutdown()
+        except Exception:
+            self.fail()

opentelemetry-sdk/tests/metrics/test_metric_reader.py

@@ -13,12 +13,12 @@
 # limitations under the License.
 
 from os import environ
-from typing import Dict
+from typing import Dict, Iterable
 from unittest import TestCase
 from unittest.mock import patch
 
-from opentelemetry.sdk._metrics._internal.aggregation import Aggregation
 from opentelemetry.sdk._metrics.aggregation import (
+    Aggregation,
     DefaultAggregation,
     LastValueAggregation,
 )
@@ -31,7 +31,7 @@
     UpDownCounter,
 )
 from opentelemetry.sdk._metrics.metric_reader import MetricReader
-from opentelemetry.sdk._metrics.point import AggregationTemporality
+from opentelemetry.sdk._metrics.point import AggregationTemporality, Metric
 from opentelemetry.sdk.environment_variables import (
     _OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE,
 )
@@ -48,10 +48,15 @@ def __init__(
             preferred_aggregation=preferred_aggregation,
         )
 
-    def _receive_metrics(self, metrics):
+    def _receive_metrics(
+        self,
+        metrics: Iterable[Metric],
+        timeout_millis: float = 10_000,
+        **kwargs,
+    ) -> None:
         pass
 
-    def shutdown(self):
+    def shutdown(self, timeout_millis: float = 30_000, **kwargs) -> None:
         return True