diff --git a/vllm/v1/engine/async_llm.py b/vllm/v1/engine/async_llm.py
index 6395d2c1875b7..a76ad96bf88ea 100644
--- a/vllm/v1/engine/async_llm.py
+++ b/vllm/v1/engine/async_llm.py
@@ -410,6 +410,8 @@ class AsyncLLM(EngineClient):
                     # 4) Logging.
                     # TODO(rob): make into a coroutine and launch it in
                     # background thread once Prometheus overhead is non-trivial.
+                    logger.info(f"{outputs.engine_index=}")
+                    logger.info(f"{stat_loggers[outputs.engine_index]=}")
                     if stat_loggers:
                         AsyncLLM._record_stats(
                             stat_loggers[outputs.engine_index],
diff --git a/vllm/v1/metrics/loggers.py b/vllm/v1/metrics/loggers.py
index c720ca13e51b2..8d879b5e98ede 100644
--- a/vllm/v1/metrics/loggers.py
+++ b/vllm/v1/metrics/loggers.py
@@ -422,6 +422,7 @@ class PrometheusStatLogger(StatLoggerBase):
 
     def record(self, scheduler_stats: Optional[SchedulerStats],
                iteration_stats: Optional[IterationStats]):
+        logger.info(f"PROM STAT LOGGER: {self.engine_index=}")
         """Log to prometheus."""
         if scheduler_stats is not None:
             self.gauge_scheduler_running.set(scheduler_stats.num_running_reqs)