fix(sync-server): thread-safe shutdown and error reporting in SyncMapServicer; remove temporary race condition test files

Signed-off-by: sapkota-aayush <[email protected]>

Author: sapkota-aayush

pynumaflow/mapper/_servicer/_sync_servicer.py

@@ -25,6 +25,22 @@ def __init__(self, handler: MapSyncCallable, multiproc: bool = False):
         self.multiproc = multiproc
         # create a thread pool for executing UDF code
         self.executor = ThreadPoolExecutor(max_workers=NUM_THREADS_DEFAULT)
+        # Thread-safe event to track shutdown state and prevent race conditions
+        self._shutdown_event = threading.Event()
+        self._shutdown_lock = threading.Lock()  # NEW: lock for shutdown/error handling
+
+    def _handle_error(self, context, error):
+        """
+        Ensures only one thread triggers shutdown and error reporting.
+        """
+        with self._shutdown_lock:
+            if not self._shutdown_event.is_set():
+                self._shutdown_event.set()
+                exit_on_error(
+                    context, f"{ERR_UDF_EXCEPTION_STRING}: {repr(error)}", parent=self.multiproc
+                )
+            else:
+                _LOGGER.info("Shutdown already initiated by another thread, exiting quietly")
 
     def MapFn(
         self,
@@ -56,10 +72,7 @@ def MapFn(
             for res in result_queue.read_iterator():
                 # if error handler accordingly
                 if isinstance(res, BaseException):
-                    # Terminate the current server process due to exception
-                    exit_on_error(
-                        context, f"{ERR_UDF_EXCEPTION_STRING}: {repr(res)}", parent=self.multiproc
-                    )
+                    self._handle_error(context, res)
                     return
                 # return the result
                 yield res
@@ -70,10 +83,7 @@ def MapFn(
 
         except BaseException as err:
             _LOGGER.critical("UDFError, re-raising the error", exc_info=True)
-            # Terminate the current server process due to exception
-            exit_on_error(
-                context, f"{ERR_UDF_EXCEPTION_STRING}: {repr(err)}", parent=self.multiproc
-            )
+            self._handle_error(context, err)
             return
 
     def _process_requests(
@@ -86,6 +96,10 @@ def _process_requests(
             # read through all incoming requests and submit to the
             # threadpool for invocation
             for request in request_iterator:
+                # Check if shutdown has been initiated before submitting new tasks
+                if self._shutdown_event.is_set():
+                    _LOGGER.info("Shutdown initiated, stopping request processing")
+                    break
                 _ = self.executor.submit(self._invoke_map, context, request, result_queue)
             # wait for all tasks to finish after all requests exhausted
             self.executor.shutdown(wait=True)
@@ -101,6 +115,11 @@ def _invoke_map(
         result_queue: SyncIterator,
     ):
         try:
+            # Check if shutdown has been initiated before processing
+            if self._shutdown_event.is_set():
+                _LOGGER.info("Shutdown initiated, skipping map invocation")
+                return
+
             d = Datum(
                 keys=list(request.request.keys),
                 value=request.request.value,
@@ -123,7 +142,11 @@ def _invoke_map(
 
         except BaseException as e:
             _LOGGER.critical("MapFn handler error", exc_info=True)
-            result_queue.put(e)
+            # Only put the exception in the queue if shutdown hasn't been initiated
+            if not self._shutdown_event.is_set():
+                result_queue.put(e)
+            else:
+                _LOGGER.info("Shutdown already initiated, not queuing additional error")
             return
 
     def IsReady(