Only set multiprocessing start method if it is not already set

Signed-off-by: Sivanantham Chinnaiyan <sivanantham.chinnaiyan@ideas2it.com>

python/kserve/kserve/errors.py

@@ -88,6 +88,14 @@ def __str__(self):
         return self.error_msg
 
 
+class UnsupportedProcessStartMethod(RuntimeError):
+    def __init__(self, start_method: str):
+        self.error_msg = f"Unsupported multi processing start method '{start_method}'. Only 'fork' is supported."
+
+    def __str__(self):
+        return self.error_msg
+
+
 async def exception_handler(_, exc):
     logger.error("Exception:", exc_info=exc)
     return JSONResponse(status_code=HTTPStatus.INTERNAL_SERVER_ERROR, content={"error": str(exc)})

python/kserve/kserve/model_server.py

@@ -26,6 +26,7 @@
 from ray.serve.api import Deployment
 from ray.serve.handle import RayServeHandle
 
+from .errors import UnsupportedProcessStartMethod
 from .logging import KSERVE_LOG_CONFIG, logger
 from .model import Model
 from .model_repository import ModelRepository
@@ -203,7 +204,12 @@ async def serve():
                 serversocket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
                 serversocket.bind(('0.0.0.0', self.http_port))
                 serversocket.listen(5)
-                multiprocessing.set_start_method('fork')
+                start_method = multiprocessing.get_start_method(allow_none=True)
+                if start_method is None:
+                    logger.info("Setting 'fork' as multiprocessing start method.")
+                    multiprocessing.set_start_method('fork')
+                elif start_method in ['spawn', 'forkserver']:
+                    raise UnsupportedProcessStartMethod(start_method)
                 self._rest_server = UvicornServer(self.http_port, [serversocket],
                                                   self.dataplane, self.model_repository_extension,
                                                   self.enable_docs_url, log_config=self.log_config,