Temporarily disable populate_db parallelism to support Django 1.6.

We don't really take good advantage of the parallelism anyway (though
it is very useful if you want to make 10000 messages, we don't do that
often).  If we decide we need that functionality, we can figure out
what the right way is to do threads with this stuff.

(imported from commit 98aa4b54fab6fd437b7c7ac0c3c7e658d2f8cb33)

zilencer/management/commands/populate_db.py

@@ -11,7 +11,6 @@ from zerver.models import Message, UserProfile, Stream, Recipient, Client, \
 from zerver.lib.actions import do_send_message, set_default_streams, \
     do_activate_user, do_deactivate, do_change_password
 from zerver.lib.parallel import run_parallel
-from django.db import transaction, connection
 from django.db.models import Count
 from django.conf import settings
 from zerver.lib.bulk_create import bulk_create_realms, \
@@ -184,11 +183,9 @@ class Command(BaseCommand):
             if i < options["num_messages"] % threads:
                 count += 1
             jobs.append((count, personals_pairs, options, self.stdout.write))
-        for status, job in run_parallel(send_messages, jobs, threads=threads):
-            pass
-        # Get a new database connection, after our parallel jobs
-        # closed the original one
-        connection.close()
+
+        for job in jobs:
+            send_messages(job)
 
         if options["delete"]:
             # Create the "website" and "API" clients; if we don't, the
@@ -256,13 +253,11 @@ class Command(BaseCommand):
                 create_users(realms, internal_zulip_users_nosubs, bot=True)
 
             # Mark all messages as read
-            with transaction.commit_on_success():
-                UserMessage.objects.all().update(flags=UserMessage.flags.read)
+            UserMessage.objects.all().update(flags=UserMessage.flags.read)
 
             self.stdout.write("Successfully populated test database.\n")
         if options["replay_old_messages"]:
             restore_saved_messages()
-        connection.close()
 
 recipient_hash = {}
 def get_recipient_by_id(rid):
@@ -677,10 +672,9 @@ def restore_saved_messages():
                          active=pending_subs[pending_sub])
         subscriptions_to_add.append(s)
     Subscription.objects.bulk_create(subscriptions_to_add)
-    with transaction.commit_on_success():
-        for (sub, active) in subscriptions_to_change:
-            current_subs_obj[sub].active = active
-            current_subs_obj[sub].save(update_fields=["active"])
+    for (sub, active) in subscriptions_to_change:
+        current_subs_obj[sub].active = active
+        current_subs_obj[sub].save(update_fields=["active"])
 
     subs = {}
     for sub in Subscription.objects.all():
@@ -699,15 +693,14 @@ def restore_saved_messages():
     print datetime.datetime.now(), "Filling in user pointers..."
 
     # Set restored pointers to the very latest messages
-    with transaction.commit_on_success():
-        for user_profile in UserProfile.objects.all():
-            try:
-                top = UserMessage.objects.filter(
-                    user_profile_id=user_profile.id).order_by("-message")[0]
-                user_profile.pointer = top.message_id
-            except IndexError:
-                user_profile.pointer = -1
-            user_profile.save(update_fields=["pointer"])
+    for user_profile in UserProfile.objects.all():
+        try:
+            top = UserMessage.objects.filter(
+                user_profile_id=user_profile.id).order_by("-message")[0]
+            user_profile.pointer = top.message_id
+        except IndexError:
+            user_profile.pointer = -1
+        user_profile.save(update_fields=["pointer"])
 
     print datetime.datetime.now(), "Done replaying old messages"
 
@@ -721,9 +714,6 @@ def restore_saved_messages():
 def send_messages(data):
     (tot_messages, personals_pairs, options, output) = data
     random.seed(os.getpid())
-    # Close the database connection, so that we get a new one that
-    # isn't shared with the other threads
-    connection.close()
     texts = file("zilencer/management/commands/test_messages.txt", "r").readlines()
     offset = random.randint(0, len(texts))
 
@@ -740,7 +730,6 @@ def send_messages(data):
     random_max = 1000000
     recipients = {}
     while num_messages < tot_messages:
-      with transaction.commit_on_success():
         saved_data = ''
         message = Message()
         message.sending_client = get_client('populate_db')
@@ -795,5 +784,4 @@ def send_messages(data):
 
         recipients[num_messages] = [message_type, message.recipient.id, saved_data]
         num_messages += 1
-    connection.close()
     return tot_messages