From 9e11ee11b2ddbb860cad63c6c64fdbc57480fed7 Mon Sep 17 00:00:00 2001
From: "jaipilot[bot]" <273169020+jaipilot[bot]@users.noreply.github.com>
Date: Sat, 22 Aug 2026 08:22:42 +0000
Subject: [PATCH] Skip scheduling a redundant timeout task for
 synchronously-completed metric exports

---
 .../metrics/export/PeriodicMetricReader.java  |  7 ++++++
 .../export/PeriodicMetricReaderTest.java      | 24 +++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/sdk/metrics/src/main/java/io/opentelemetry/sdk/metrics/export/PeriodicMetricReader.java b/sdk/metrics/src/main/java/io/opentelemetry/sdk/metrics/export/PeriodicMetricReader.java
index d44a95226e1..6e2efd69f8f 100644
--- a/sdk/metrics/src/main/java/io/opentelemetry/sdk/metrics/export/PeriodicMetricReader.java
+++ b/sdk/metrics/src/main/java/io/opentelemetry/sdk/metrics/export/PeriodicMetricReader.java
@@ -263,6 +263,13 @@ private CompletableResultCode applyTimeout(CompletableResultCode result) {
       if (exporterTimeoutNanos == Long.MAX_VALUE) {
         return result;
       }
+      if (result.isDone()) {
+        // Already complete (e.g. a synchronous exporter) - scheduling a timeout task would be
+        // wasted work, since it would immediately be cancelled.
+        return result.isSuccess()
+            ? CompletableResultCode.ofSuccess()
+            : CompletableResultCode.ofFailure();
+      }
 
       try {
         CompletableResultCode timeoutResult = new CompletableResultCode();
diff --git a/sdk/metrics/src/test/java/io/opentelemetry/sdk/metrics/export/PeriodicMetricReaderTest.java b/sdk/metrics/src/test/java/io/opentelemetry/sdk/metrics/export/PeriodicMetricReaderTest.java
index 64797cbaf8e..d7023e4f9ad 100644
--- a/sdk/metrics/src/test/java/io/opentelemetry/sdk/metrics/export/PeriodicMetricReaderTest.java
+++ b/sdk/metrics/src/test/java/io/opentelemetry/sdk/metrics/export/PeriodicMetricReaderTest.java
@@ -10,6 +10,7 @@
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyLong;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.spy;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
@@ -860,6 +861,29 @@ void timeoutEnforcement_failsSlowExporter() throws Exception {
     }
   }
 
+  @Test
+  @SuppressWarnings({"rawtypes", "unchecked"})
+  void applyTimeout_skipsSchedulingForSynchronouslyCompletedExport() {
+    // A timeout is only useful for exports that have not already finished. When the exporter
+    // completes synchronously, no timeout task should be scheduled since it would be immediately
+    // cancelled.
+    ScheduledExecutorService scheduler = mock(ScheduledExecutorService.class);
+    when(scheduler.scheduleAtFixedRate(any(), anyLong(), anyLong(), any()))
+        .thenReturn(mock(ScheduledFuture.class));
+    when(scheduler.schedule(any(Runnable.class), anyLong(), any(TimeUnit.class)))
+        .thenReturn(mock(ScheduledFuture.class));
+    when(metricExporter.export(any())).thenReturn(CompletableResultCode.ofSuccess());
+    when(metricExporter.flush()).thenReturn(CompletableResultCode.ofSuccess());
+
+    PeriodicMetricReader reader =
+        PeriodicMetricReader.builder(metricExporter).setExecutor(scheduler).build();
+    reader.register(collectionRegistration);
+
+    assertThat(reader.forceFlush().join(5, TimeUnit.SECONDS).isSuccess()).isTrue();
+
+    verify(scheduler, never()).schedule(any(Runnable.class), anyLong(), any(TimeUnit.class));
+  }
+
   // Helper test classes for timeout testing
   private static class DelayingMetricExporter implements MetricExporter {
     private final long delayMs;