[Mellanox] set select timeout to no more than 1 sec to make sure fast shutdown (sonic-net#13611) (sonic-net#16448)

Author: mssonicbld

platform/mellanox/mlnx-platform-api/sonic_platform/chassis.py

@@ -31,10 +31,10 @@
     from . import utils
     from .device_data import DeviceDataManager
     import re
+    import time
 except ImportError as e:
     raise ImportError (str(e) + "- required module not found")
 
-MAX_SELECT_DELAY = 3600
 
 RJ45_TYPE = "RJ45"
 
@@ -387,26 +387,30 @@ def get_change_event(self, timeout=0):
             self.sfp_event.initialize()
 
         wait_for_ever = (timeout == 0)
+        # select timeout should be no more than 1000ms to ensure fast shutdown flow
+        select_timeout = 1000.0 if timeout >= 1000 else float(timeout)
         port_dict = {}
         error_dict = {}
-        if wait_for_ever:
-            timeout = MAX_SELECT_DELAY
-            while True:
-                status = self.sfp_event.check_sfp_status(port_dict, error_dict, timeout)
-                if bool(port_dict):
+        begin = time.time()
+        while True:
+            status = self.sfp_event.check_sfp_status(port_dict, error_dict, select_timeout)
+            if bool(port_dict):
+                break
+
+            if not wait_for_ever:
+                elapse = time.time() - begin
+                if elapse * 1000 > timeout:
                     break
-        else:
-            status = self.sfp_event.check_sfp_status(port_dict, error_dict, timeout)
 
         if status:
             if port_dict:
                 self.reinit_sfps(port_dict)
-            result_dict = {'sfp':port_dict}
+            result_dict = {'sfp': port_dict}
             if error_dict:
                 result_dict['sfp_error'] = error_dict
             return True, result_dict
         else:
-            return True, {'sfp':{}}
+            return True, {'sfp': {}}
 
     def reinit_sfps(self, port_dict):
         """