[aws2] Make SqsIOWriteBatchesTest timeout tests timing-independent

The four timeout-related tests asserted the exact grouping of messages into
SendMessageBatch calls. Those groupings depend on wall-clock timing (the
per-message Thread.sleep delay racing the configured batch timeout), so on
loaded CI runners batches form differently and the strict
verify(...).sendMessageBatch(request(exact entries)) checks fail with
Mockito ArgumentsAreDifferent.

Rewrite the assertions to verify timing-independent invariants instead:
all expected message bodies are sent exactly once, no batch exceeds the
size implied by the timeout cadence, and at least the minimum number of
batches is produced. This still exercises the timeout-driven flushing
(both synchronous and the strict separate-thread variant) without
depending on exact wall-clock behavior.

Fixes #38946

Author: tkaymak

sdks/java/io/amazon-web-services2/src/test/java/org/apache/beam/sdk/io/aws2/sqs/SqsIOWriteBatchesTest.java

@@ -21,6 +21,7 @@
 import static java.nio.charset.StandardCharsets.UTF_8;
 import static java.util.concurrent.CompletableFuture.completedFuture;
 import static java.util.concurrent.CompletableFuture.supplyAsync;
+import static java.util.stream.Collectors.groupingBy;
 import static java.util.stream.Collectors.toList;
 import static java.util.stream.IntStream.range;
 import static org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions.checkNotNull;
@@ -30,6 +31,7 @@
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.atLeast;
 import static org.mockito.Mockito.atLeastOnce;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
@@ -38,6 +40,7 @@
 
 import java.util.Arrays;
 import java.util.HashSet;
+import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.stream.Collectors;
@@ -60,6 +63,7 @@
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.ImmutableMap;
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Streams;
 import org.apache.commons.lang3.RandomUtils;
+import org.checkerframework.checker.nullness.qual.Nullable;
 import org.joda.time.Duration;
 import org.junit.Before;
 import org.junit.Rule;
@@ -263,10 +267,16 @@ public void testWriteBatchesWithTimeout() {
 
     p.run().waitUntilFinish();
 
-    SendMessageBatchRequestEntry[] entries = entries(range(0, 5));
-    // due to added delay, batches are timed out on arrival of every 3rd msg
-    verify(sqs).sendMessageBatch(request("queue", entries[0], entries[1], entries[2]));
-    verify(sqs).sendMessageBatch(request("queue", entries[3], entries[4]));
+    // Nominally batches time out on arrival of every 3rd message ([0,1,2], [3,4]). The exact
+    // grouping depends on wall clock time and is unreliable on loaded machines (#38946), so
+    // verify timing-independent invariants instead: expired batches are flushed on append, so
+    // with >= 100ms between messages no batch can exceed 3 entries before exceeding the 150ms
+    // timeout, forcing at least 2 batches for 5 messages.
+    Map<String, List<SendMessageBatchRequest>> requests = captureBatchRequests(atLeast(2));
+    assertThat(requests.keySet()).containsExactly("queue");
+    assertMessageBodies(requests.get("queue"), range(0, 5));
+    assertThat(requests.get("queue"))
+        .allSatisfy(req -> assertThat(req.entries().size()).isLessThanOrEqualTo(3));
   }
 
   @Test
@@ -285,11 +295,16 @@ public void testWriteBatchesWithStrictTimeout() {
 
     p.run().waitUntilFinish();
 
-    SendMessageBatchRequestEntry[] entries = entries(range(0, 5));
-    // using strict timeouts batches, batches are timed out by a separate thread
-    verify(sqs).sendMessageBatch(request("queue", entries[0], entries[1]));
-    verify(sqs).sendMessageBatch(request("queue", entries[2], entries[3]));
-    verify(sqs).sendMessageBatch(request("queue", entries[4]));
+    // Nominally the separate timeout thread flushes [0,1], [2,3], [4]. The exact grouping
+    // depends on wall clock time and is unreliable on loaded machines (#38946), so verify
+    // timing-independent invariants instead. Expired batches are also flushed on append
+    // (independently of the timeout thread), so no batch can exceed 3 entries and 5 messages
+    // require at least 2 batches.
+    Map<String, List<SendMessageBatchRequest>> requests = captureBatchRequests(atLeast(2));
+    assertThat(requests.keySet()).containsExactly("queue");
+    assertMessageBodies(requests.get("queue"), range(0, 5));
+    assertThat(requests.get("queue"))
+        .allSatisfy(req -> assertThat(req.entries().size()).isLessThanOrEqualTo(3));
   }
 
   @Test
@@ -337,11 +352,18 @@ public void testWriteBatchesToDynamicWithTimeout() {
 
     p.run().waitUntilFinish();
 
-    SendMessageBatchRequestEntry[] entries = entries(range(0, 5));
-    // due to added delay, dynamic batches are timed out on arrival of every 2nd msg (per batch)
-    verify(sqs).sendMessageBatch(request("even", entries[0], entries[2]));
-    verify(sqs).sendMessageBatch(request("uneven", entries[1], entries[3]));
-    verify(sqs).sendMessageBatch(request("even", entries[4]));
+    // Nominally dynamic batches are timed out on arrival of every 2nd message per batch
+    // ([0,2], [1,3], [4]). The exact grouping depends on wall clock time and is unreliable on
+    // loaded machines (#38946), so verify timing-independent invariants instead: per queue,
+    // consecutive messages are >= 200ms apart, so expired batches are flushed on append once
+    // reaching 2 entries, requiring at least 3 batches overall.
+    Map<String, List<SendMessageBatchRequest>> requests = captureBatchRequests(atLeast(3));
+    assertThat(requests.keySet()).containsExactlyInAnyOrder("even", "uneven");
+    assertMessageBodies(requests.get("even"), range(0, 5).filter(i -> i % 2 == 0));
+    assertMessageBodies(requests.get("uneven"), range(0, 5).filter(i -> i % 2 == 1));
+    requests.values().stream()
+        .flatMap(List::stream)
+        .forEach(req -> assertThat(req.entries().size()).isLessThanOrEqualTo(2));
   }
 
   @Test
@@ -360,14 +382,19 @@ public void testWriteBatchesToDynamicWithStrictTimeout() {
 
     p.run().waitUntilFinish();
 
-    SendMessageBatchRequestEntry[] entries = entries(range(0, 5));
-    // using strict timeouts batches, batches are timed out by a separate thread before any 2nd
-    // entry
-    verify(sqs).sendMessageBatch(request("even", entries[0]));
-    verify(sqs).sendMessageBatch(request("uneven", entries[1]));
-    verify(sqs).sendMessageBatch(request("even", entries[2]));
-    verify(sqs).sendMessageBatch(request("uneven", entries[3]));
-    verify(sqs).sendMessageBatch(request("even", entries[4]));
+    // Nominally the separate timeout thread flushes every batch before a 2nd entry arrives
+    // (5 singleton batches). The exact grouping depends on wall clock time and is unreliable
+    // on loaded machines (#38946), so verify timing-independent invariants instead. Expired
+    // batches are also flushed on append (independently of the timeout thread) and per queue
+    // consecutive messages are >= 200ms apart, so no batch can exceed 2 entries and at least
+    // 3 batches are required overall.
+    Map<String, List<SendMessageBatchRequest>> requests = captureBatchRequests(atLeast(3));
+    assertThat(requests.keySet()).containsExactlyInAnyOrder("even", "uneven");
+    assertMessageBodies(requests.get("even"), range(0, 5).filter(i -> i % 2 == 0));
+    assertMessageBodies(requests.get("uneven"), range(0, 5).filter(i -> i % 2 == 1));
+    requests.values().stream()
+        .flatMap(List::stream)
+        .forEach(req -> assertThat(req.entries().size()).isLessThanOrEqualTo(2));
   }
 
   @Test
@@ -406,6 +433,28 @@ private SendMessageBatchRequest anyRequest() {
     return any();
   }
 
+  /** Captures all batch requests, verifying the given mode, and groups them by queue url. */
+  private Map<String, List<SendMessageBatchRequest>> captureBatchRequests(
+      org.mockito.verification.VerificationMode mode) {
+    ArgumentCaptor<SendMessageBatchRequest> captor =
+        ArgumentCaptor.forClass(SendMessageBatchRequest.class);
+    verify(sqs, mode).sendMessageBatch(captor.capture());
+    return captor.getAllValues().stream().collect(groupingBy(SendMessageBatchRequest::queueUrl));
+  }
+
+  /** Asserts that the requests contain exactly the expected message bodies, each exactly once. */
+  private void assertMessageBodies(
+      @Nullable List<SendMessageBatchRequest> requests, IntStream expectedMsgs) {
+    assertThat(requests).isNotNull();
+    assertThat(
+            requests.stream()
+                .flatMap(req -> req.entries().stream())
+                .map(SendMessageBatchRequestEntry::messageBody)
+                .collect(toList()))
+        .containsExactlyInAnyOrderElementsOf(
+            expectedMsgs.mapToObj(Integer::toString).collect(toList()));
+  }
+
   private SendMessageBatchRequest request(String queue, SendMessageBatchRequestEntry... entries) {
     return SendMessageBatchRequest.builder()
         .queueUrl(queue)