restart-server: Fix restarting server with multiple tornado processes.

Previously, we unconditionally tried to restart the Tornado process
name corresponding to the historically always-true case of a single
Tornado process.  This resulted in Tornado not being automatically
restarted on a production deployment on servers with more than one
Tornado process configured.

scripts/lib/upgrade-zulip-stage-2

@@ -5,6 +5,7 @@
 # always run from the new version of Zulip, so any bug fixes take
 # effect on the very next upgrade.
 import argparse
+import configparser
 import hashlib
 import subprocess
 import os
@@ -45,6 +46,13 @@ args = parser.parse_args()
 deploy_path = args.deploy_path
 os.chdir(deploy_path)
 
+config_file = configparser.RawConfigParser()
+config_file.read("/etc/zulip/zulip.conf")
+try:
+    tornado_processes = int(config_file.get('application_server', 'tornado_processes'))
+except (configparser.NoSectionError, configparser.NoOptionError):
+    tornado_processes = 1
+
 # Handle issues around upstart on Ubuntu Xenial
 subprocess.check_call(["./scripts/lib/check-upstart"])
 
@@ -139,7 +147,8 @@ if not args.skip_migrations:
 if os.path.exists("/etc/supervisor/conf.d/zulip_db.conf"):
     subprocess.check_call(["supervisorctl", "stop", "process-fts-updates"], preexec_fn=su_to_zulip)
 
-core_server_services = ["zulip-django", "zulip-tornado", "zulip-senders:*"]
+core_server_services = ["zulip-django", "zulip-senders:*",
+                        "zulip-tornado" if tornado_processes == 1 else "zulip-tornado:*"]
 worker_services = ["zulip-workers:*"]
 # Stop and start thumbor service only if thumbor is installed.
 if os.path.exists("/etc/supervisor/conf.d/thumbor.conf"):

scripts/restart-server

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+import configparser
 import os
 import sys
 import pwd
@@ -36,12 +37,23 @@ if os.readlink(current_symlink) != deploy_path:
     subprocess.check_call(["ln", '-nsf', os.readlink(current_symlink), last_symlink])
     subprocess.check_call(["ln", '-nsf', deploy_path, current_symlink])
 
+config_file = configparser.RawConfigParser()
+config_file.read("/etc/zulip/zulip.conf")
+
+try:
+    tornado_processes = int(config_file.get('application_server', 'tornado_processes'))
+except (configparser.NoSectionError, configparser.NoOptionError):
+    tornado_processes = 1
+
 # We restart just the zulip-tornado service early, in order to
 # minimize downtime of the tornado service caused by too many Python
 # processes restarting at the same time resulting in it receiving
 # insufficient priority.  This is important, because Tornado is the
 # main source of user-visible downtime when we restart a Zulip server.
-subprocess.check_call(["supervisorctl", "restart", "zulip-tornado"])
+if tornado_processes > 1:
+    subprocess.check_call(["supervisorctl", "restart", "zulip-tornado:*"])
+else:
+    subprocess.check_call(["supervisorctl", "restart", "zulip-tornado", "zulip-tornado:*"])
 
 # Restart the uWSGI and related processes via supervisorctl.
 logging.info("Stopping workers")