render_messages: Use JSON Lines format.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

zilencer/management/commands/compare_messages.py

@@ -1,6 +1,6 @@
 from typing import Any
 
-import ijson
+import orjson
 from django.core.management.base import BaseCommand, CommandParser
 
 
@@ -18,7 +18,9 @@ class Command(BaseCommand):
         total_count = 0
         changed_count = 0
         with open(options["dump1"]) as dump1, open(options["dump2"]) as dump2:
-            for m1, m2 in zip(ijson.items(dump1, "item"), ijson.items(dump2, "item")):
+            for line1, line2 in zip(dump1, dump2):
+                m1 = orjson.loads(line1)
+                m2 = orjson.loads(line2)
                 total_count += 1
                 if m1["id"] != m2["id"]:
                     self.stderr.write("Inconsistent messages dump")

zilencer/management/commands/render_messages.py

@@ -38,7 +38,6 @@ class Command(BaseCommand):
             os.makedirs(dest_dir)
 
         with open(options["destination"], "wb") as result:
-            result.write(b"[")
             messages = Message.objects.filter(id__gt=latest - amount, id__lte=latest).order_by("id")
             for message in queryset_iterator(messages):
                 content = message.content
@@ -59,9 +58,7 @@ class Command(BaseCommand):
                         {
                             "id": message.id,
                             "content": render_markdown(message, content),
-                        }
+                        },
+                        option=orjson.OPT_APPEND_NEWLINE,
                     )
                 )
-                if message.id != latest:
-                    result.write(b",")
-            result.write(b"]")