fix: respect timeout_millis in BatchProcessor.force_flush

Fixes #4568.

Author: chimchim89

opentelemetry-sdk/tests/shared_internal/test_batch_processor.py

@@ -199,26 +199,26 @@ def test_force_flush_returns_false_when_timeout_exceeded(
         def slow_export(batch):
             nonlocal call_count
             call_count += 1
-            # Sleep long enough that the deadline is exceeded after first batch.
-            time.sleep(0.2)
+            # Sleep longer than the force_flush timeout.
+            time.sleep(0.5)
 
         exporter = Mock()
         exporter.export.side_effect = slow_export
         batch_processor = batch_processor_class(
             exporter,
             max_queue_size=200,
-            max_export_batch_size=1,
+            max_export_batch_size=200,
             # Long enough that the worker thread won't wake up during the test.
             schedule_delay_millis=30000,
             export_timeout_millis=500,
         )
-        for _ in range(50):
+        for _ in range(10):
             batch_processor._batch_processor.emit(telemetry)
-        # 100ms timeout, each export takes 200ms, so deadline is hit after first batch.
+        # force_flush acquires lock immediately since worker is sleeping for 30s.
+        # First export takes 500ms, deadline of 100ms fires before second batch.
         result = batch_processor.force_flush(timeout_millis=100)
         assert result is False
-        # Exporter was called at least once but not for all batches.
-        assert 1 <= call_count < 50
+        assert call_count == 1
         batch_processor.shutdown()
 
     # pylint: disable=no-self-use