From 967831ff8be3c4c09c4e00069ee0218143071434 Mon Sep 17 00:00:00 2001
From: Sangkyoon Nam <sangkyoon.nam@namsang.co>
Date: Wed, 16 Sep 2026 12:50:43 +0900
Subject: [PATCH] Report activity retry scheduled time after backoff in the
 test server

---
 .../ActivityRetryScheduledTimeTest.java       | 110 ++++++++++++++++++
 .../internal/testservice/StateMachines.java   |   3 +-
 2 files changed, 112 insertions(+), 1 deletion(-)
 create mode 100644 temporal-sdk/src/test/java/io/temporal/workflow/activityTests/ActivityRetryScheduledTimeTest.java

diff --git a/temporal-sdk/src/test/java/io/temporal/workflow/activityTests/ActivityRetryScheduledTimeTest.java b/temporal-sdk/src/test/java/io/temporal/workflow/activityTests/ActivityRetryScheduledTimeTest.java
new file mode 100644
index 0000000000..02284b7ae9
--- /dev/null
+++ b/temporal-sdk/src/test/java/io/temporal/workflow/activityTests/ActivityRetryScheduledTimeTest.java
@@ -0,0 +1,110 @@
+package io.temporal.workflow.activityTests;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assume.assumeFalse;
+
+import io.temporal.activity.Activity;
+import io.temporal.activity.ActivityInfo;
+import io.temporal.activity.ActivityInterface;
+import io.temporal.activity.ActivityMethod;
+import io.temporal.activity.ActivityOptions;
+import io.temporal.common.RetryOptions;
+import io.temporal.testing.internal.SDKTestWorkflowRule;
+import io.temporal.workflow.Workflow;
+import io.temporal.workflow.shared.TestWorkflows.TestWorkflow1;
+import java.time.Duration;
+import java.util.ArrayList;
+import java.util.List;
+import org.junit.Rule;
+import org.junit.Test;
+
+/**
+ * Verifies that the scheduled time reported for each activity retry attempt reflects the retry
+ * backoff. Regression test for the test server stamping the retry attempt's scheduled time with the
+ * failure time instead of the time the retry is due, which made the first retry look immediate.
+ */
+public class ActivityRetryScheduledTimeTest {
+
+  private static final Duration INITIAL_INTERVAL = Duration.ofSeconds(10);
+  private static final int BACKOFF_COEFFICIENT = 2;
+  private static final int ATTEMPTS = 4;
+
+  private final RecordingActivityImpl activity = new RecordingActivityImpl();
+
+  @Rule
+  public SDKTestWorkflowRule testWorkflowRule =
+      SDKTestWorkflowRule.newBuilder()
+          .setWorkflowTypes(TestActivityRetryScheduledTime.class)
+          .setActivityImplementations(activity)
+          .build();
+
+  @Test
+  public void retryScheduledTimeFollowsBackoff() {
+    // Test server regression test: with a real server the retries take over a minute of wall time.
+    assumeFalse("skipping for docker tests", SDKTestWorkflowRule.useExternalService);
+    TestWorkflow1 workflowStub =
+        testWorkflowRule.newWorkflowStubTimeoutOptions(TestWorkflow1.class);
+    workflowStub.execute(testWorkflowRule.getTaskQueue());
+
+    List<Long> scheduled = activity.scheduledTimestamps;
+    assertEquals(ATTEMPTS, scheduled.size());
+    Duration expected = INITIAL_INTERVAL;
+    for (int i = 1; i < scheduled.size(); i++) {
+      Duration actual = Duration.ofMillis(scheduled.get(i) - scheduled.get(i - 1));
+      // The gap also includes the previous attempt's queueing and failure handling, so allow
+      // slack around the backoff.
+      Duration lowerBound = expected.minusSeconds(1);
+      Duration upperBound = expected.plusSeconds(5);
+      assertTrue(
+          "attempt "
+              + (i + 1)
+              + " scheduled "
+              + actual
+              + " after previous, expected between "
+              + lowerBound
+              + " and "
+              + upperBound,
+          actual.compareTo(lowerBound) >= 0 && actual.compareTo(upperBound) <= 0);
+      expected = expected.multipliedBy(BACKOFF_COEFFICIENT);
+    }
+  }
+
+  @ActivityInterface
+  public interface RecordingActivity {
+    @ActivityMethod
+    void run();
+  }
+
+  public static class RecordingActivityImpl implements RecordingActivity {
+    final List<Long> scheduledTimestamps = new ArrayList<>();
+
+    @Override
+    public void run() {
+      ActivityInfo info = Activity.getExecutionContext().getInfo();
+      scheduledTimestamps.add(info.getCurrentAttemptScheduledTimestamp());
+      if (info.getAttempt() < ATTEMPTS) {
+        throw new RuntimeException("retry attempt " + info.getAttempt());
+      }
+    }
+  }
+
+  public static class TestActivityRetryScheduledTime implements TestWorkflow1 {
+    @Override
+    public String execute(String taskQueue) {
+      ActivityOptions options =
+          ActivityOptions.newBuilder()
+              .setTaskQueue(taskQueue)
+              .setStartToCloseTimeout(Duration.ofMinutes(5))
+              .setRetryOptions(
+                  RetryOptions.newBuilder()
+                      .setInitialInterval(INITIAL_INTERVAL)
+                      .setBackoffCoefficient(BACKOFF_COEFFICIENT)
+                      .setMaximumAttempts(ATTEMPTS)
+                      .build())
+              .build();
+      Workflow.newActivityStub(RecordingActivity.class, options).run();
+      return "done";
+    }
+  }
+}
diff --git a/temporal-test-server/src/main/java/io/temporal/internal/testservice/StateMachines.java b/temporal-test-server/src/main/java/io/temporal/internal/testservice/StateMachines.java
index fce9d3ae01..da7eda8815 100644
--- a/temporal-test-server/src/main/java/io/temporal/internal/testservice/StateMachines.java
+++ b/temporal-test-server/src/main/java/io/temporal/internal/testservice/StateMachines.java
@@ -2264,7 +2264,8 @@ private static RetryState attemptActivityRetry(
             data.retryState = nextAttempt;
             data.lastAttemptCompleteTime = ctx.currentTime();
             task.setAttempt(nextAttempt.getAttempt());
-            task.setCurrentAttemptScheduledTime(ctx.currentTime());
+            task.setCurrentAttemptScheduledTime(
+                Timestamps.add(ctx.currentTime(), data.nextBackoffInterval));
           });
     } else {
       data.nextBackoffInterval = Durations.ZERO;