[Multi NPU] Time Improvements to the config reload/load_minigraph com…

…mands (sonic-net#917)

* Improvements to the config reload/load_minigraph commands in Multi NPU platforms by parallelizing with threads.

config/main.py

@@ -9,6 +9,7 @@
 import syslog
 import time
 import netifaces
+import threading
 
 import sonic_device_util
 import ipaddress
@@ -121,6 +122,16 @@ def get_command(self, ctx, cmd_name):
 # Helper functions
 #
 
+# Execute action per NPU instance for multi instance services.
+def execute_systemctl_per_asic_instance(inst, event, service, action):
+    try:
+        click.echo("Executing {} of service {}@{}...".format(action, service, inst))
+        run_command("systemctl {} {}@{}.service".format(action, service, inst))
+    except SystemExit as e:
+        log_error("Failed to execute {} of service {}@{} with error {}".format(action, service, inst, e))
+        # Set the event object if there is a failure and exception was raised.
+        event.set()
+
 # Execute action on list of systemd services
 def execute_systemctl(list_of_services, action):
     num_asic = sonic_device_util.get_num_npus()
@@ -138,14 +149,27 @@ def execute_systemctl(list_of_services, action):
             except SystemExit as e:
                 log_error("Failed to execute {} of service {} with error {}".format(action, service, e))
                 raise
+
         if (service + '.service' in generated_multi_instance_services):
-            for inst in range(num_asic):
-                try:
-                    click.echo("Executing {} of service {}@{}...".format(action, service, inst))
-                    run_command("systemctl {} {}@{}.service".format(action, service, inst))
-                except SystemExit as e:
-                    log_error("Failed to execute {} of service {}@{} with error {}".format(action, service, inst, e))
-                    raise
+            # With Multi NPU, Start a thread per instance to do the "action" on multi instance services.
+            if sonic_device_util.is_multi_npu():
+                threads = []
+                # Use this event object to co-ordinate if any threads raised exception
+                e = threading.Event()
+
+                kwargs = {'service': service, 'action': action}
+                for inst in range(num_asic):
+                    t = threading.Thread(target=execute_systemctl_per_asic_instance, args=(inst, e), kwargs=kwargs)
+                    threads.append(t)
+                    t.start()
+
+                # Wait for all the threads to finish.
+                for inst in range(num_asic):
+                    threads[inst].join()
+
+                    # Check if any of the threads have raised exception, if so exit the process.
+                    if e.is_set():
+                        sys.exit(1)
 
 def run_command(command, display_cmd=False, ignore_error=False):
     """Run bash command and print output to stdout