prompt: We are currently solving the following issue within our repository. Here is the issue text:
  --- BEGIN ISSUE ---
  check_live_state pop from empty list
  ## Bug Report
  
  **Problematic Behavior**
  
  The management command check_live_state has a recurring error, it tries to pop a value from an empty list. This list comes from cloudwatch service : https://github.com/openfun/marsha/blob/29e1f78ed6e288f7bba3c198bb7b7179e7af4fe0/src/backend/marsha/core/management/commands/check_live_state.py#L100
  
  **Expected behavior/code**
  
  This error seems to occur when a live has no activity anymore. We try to compare alerts set and the clear to determine if they are still active.
  
  
  **Steps to Reproduce**
  1. Start a webinar
  2. Once started, stop all activity
  3. Run the management command `check_live_state`
  4. And then the bug happens!
  
  
  
  --- END ISSUE ---
  
  Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
  --- BEGIN FILES ---
  Path: `src/backend/marsha/core/management/commands/check_live_state.py`
  Content:
  ```
  1 """Check live state management command."""
  2 
  3 from datetime import datetime, timedelta, timezone
  4 import json
  5 import re
  6 
  7 from django.conf import settings
  8 from django.core.management.base import BaseCommand
  9 
  10 import boto3
  11 from dateutil.parser import isoparse
  12 
  13 from marsha.core.defaults import RUNNING, STOPPING
  14 from marsha.core.models import Video
  15 from marsha.core.utils.medialive_utils import stop_live_channel
  16 
  17 
  18 aws_credentials = {
  19     "aws_access_key_id": settings.AWS_ACCESS_KEY_ID,
  20     "aws_secret_access_key": settings.AWS_SECRET_ACCESS_KEY,
  21     "region_name": settings.AWS_S3_REGION_NAME,
  22 }
  23 
  24 # Configure medialive client
  25 medialive_client = boto3.client("medialive", **aws_credentials)
  26 
  27 # Configure cloudwatch logs client
  28 logs_client = boto3.client("logs", **aws_credentials)
  29 
  30 
  31 def parse_iso_date(iso_date):
  32     """Parse an iso 8601 date and return a datetime object."""
  33     return isoparse(iso_date)
  34 
  35 
  36 def generate_expired_date():
  37     """Generate a datetime object 25 minutes in the past."""
  38     return datetime.now(tz=timezone.utc) - timedelta(minutes=25)
  39 
  40 
  41 # pylint: disable=too-many-locals
  42 class Command(BaseCommand):
  43     """Check every live streaming running state on AWS."""
  44 
  45     help = (
  46         "Check activity on AWS for every live streaming running"
  47         "and close them if there is not."
  48     )
  49 
  50     def handle(self, *args, **options):
  51         """Execute management command."""
  52         extract_message_pattern = (
  53             r"^(?P<ingestion_time>.*)\t"
  54             r"(?P<request_id>.*)\t"
  55             r"(?P<level>.*)\t"
  56             r"Received event:(?P<message>.*)$"
  57         )
  58         extract_message_regex = re.compile(extract_message_pattern)
  59 
  60         videos = Video.objects.filter(live_state=RUNNING)
  61         for video in videos:
  62             # For each running live video, we query cloudwatch on the current live
  63             # to search messages having detail.alert_type set to `RTMP Has No Audio/Video`.
  64             # This alert tell us there is no stream and the live can be stopped if the message is
  65             # older than 25 minutes.
  66             self.stdout.write(f"Checking video {video.id}")
  67             live_info = video.live_info
  68             logs = logs_client.filter_log_events(
  69                 logGroupName=live_info["cloudwatch"]["logGroupName"],
  70                 startTime=int(int(video.live_info.get("started_at")) * 1000),
  71                 filterPattern=(
  72                     "{"
  73                     '($.detail-type = "MediaLive Channel Alert") && '
  74                     f"($.resources[0] = \"{live_info['medialive']['channel']['arn']}\") &&"
  75                     '($.detail.alert_type = "RTMP Has No Audio/Video")'
  76                     "}"
  77                 ),
  78             )
  79 
  80             pipelines_queue = {"0": [], "1": []}
  81 
  82             for event in logs["events"]:
  83                 # All events must be parsed to extract the JSON message. When an alert is added,
  84                 # the `alarm_state` property value is `SET` and when the alert is removed,
  85                 # the `alarm_state` property value is `CLEARED`.
  86                 # We have 2 pipelines, a live is over when the 2 pipeline have `SET` value
  87                 # in `alarm_state`.
  88                 # Alarm state act like a list with all the event history. It means a `CLEARED`
  89                 # event is related to a `SET` one. So we have to look over all events, put in
  90                 # a list all `SET` events and remove it if a `CLEARED` event is here. At the
  91                 # end if we have 2 `SET` events, the live has no activity and we have to check
  92                 # the time of the last `SET` event. If this time is older than 25 minutes we
  93                 # stop the channel.
  94                 log = extract_message_regex.match(event["message"])
  95                 message = json.loads(log.group("message"))
  96 
  97                 if message["detail"]["alarm_state"] == "SET":
  98                     pipelines_queue[message["detail"]["pipeline"]].append(message)
  99                 else:
  100                     pipelines_queue[message["detail"]["pipeline"]].pop()
  101 
  102             if len(pipelines_queue["0"]) == 1 and len(pipelines_queue["1"]) == 1:
  103                 # Both pipelines receive no stream, we have to check the more recent one
  104                 # and if the time is older than 25 minutes we stop the channel.
  105                 datetime_pipeline0 = parse_iso_date(pipelines_queue["0"][0]["time"])
  106                 datetime_pipeline1 = parse_iso_date(pipelines_queue["1"][0]["time"])
  107                 expired_date = generate_expired_date()
  108 
  109                 if (
  110                     datetime_pipeline0 < expired_date
  111                     or datetime_pipeline1 < expired_date
  112                 ):
  113                     # Stop this channel
  114                     self.stdout.write(
  115                         f"Stopping channel with id {live_info['medialive']['channel']['id']}"
  116                     )
  117                     stop_live_channel(live_info["medialive"]["channel"]["id"])
  118 
  119                     video.live_state = STOPPING
  120                     video.save()
  121                     self.stdout.write("Channel stopped")
  122
  ```
  --- END FILES ---
  
  Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.
  
  Here is an example:
  
  ```diff
  diff --git a/examples/server_async.py b/examples/server_async.py
  --- a/examples/server_async.py
  +++ b/examples/server_async.py
  @@ -313,4 +313,4 @@
   
   
   if __name__ == "__main__":
  -    asyncio.run(run_async_server("."), debug=True)
  +    asyncio.run(run_async_server(), debug=True)
  diff --git a/examples/server_sync.py b/examples/server_sync.py
  --- a/examples/server_sync.py
  +++ b/examples/server_sync.py
  @@ -313,5 +313,5 @@
   
   
   if __name__ == "__main__":
  -    server = run_sync_server(".")
  +    server = run_sync_server()
       server.shutdown()
  
  ```
  
golden_diff: diff --git a/src/backend/marsha/core/management/commands/check_live_state.py b/src/backend/marsha/core/management/commands/check_live_state.py
  --- a/src/backend/marsha/core/management/commands/check_live_state.py
  +++ b/src/backend/marsha/core/management/commands/check_live_state.py
  @@ -67,7 +67,7 @@
               live_info = video.live_info
               logs = logs_client.filter_log_events(
                   logGroupName=live_info["cloudwatch"]["logGroupName"],
  -                startTime=int(int(video.live_info.get("started_at")) * 1000),
  +                startTime=int((int(video.live_info.get("started_at")) - 60) * 1000),
                   filterPattern=(
                       "{"
                       '($.detail-type = "MediaLive Channel Alert") && '
  
verification_info: {"golden_diff": "diff --git a/src/backend/marsha/core/management/commands/check_live_state.py b/src/backend/marsha/core/management/commands/check_live_state.py\n--- a/src/backend/marsha/core/management/commands/check_live_state.py\n+++ b/src/backend/marsha/core/management/commands/check_live_state.py\n@@ -67,7 +67,7 @@\n             live_info = video.live_info\n             logs = logs_client.filter_log_events(\n                 logGroupName=live_info[\"cloudwatch\"][\"logGroupName\"],\n-                startTime=int(int(video.live_info.get(\"started_at\")) * 1000),\n+                startTime=int((int(video.live_info.get(\"started_at\")) - 60) * 1000),\n                 filterPattern=(\n                     \"{\"\n                     '($.detail-type = \"MediaLive Channel Alert\") && '\n", "issue": "check_live_state pop from empty list\n## Bug Report\r\n\r\n**Problematic Behavior**\r\n\r\nThe management command check_live_state has a recurring error, it tries to pop a value from an empty list. This list comes from cloudwatch service : https://github.com/openfun/marsha/blob/29e1f78ed6e288f7bba3c198bb7b7179e7af4fe0/src/backend/marsha/core/management/commands/check_live_state.py#L100\r\n\r\n**Expected behavior/code**\r\n\r\nThis error seems to occur when a live has no activity anymore. We try to compare alerts set and the clear to determine if they are still active.\r\n\r\n\r\n**Steps to Reproduce**\r\n1. Start a webinar\r\n2. Once started, stop all activity\r\n3. Run the management command `check_live_state`\r\n4. And then the bug happens!\r\n\r\n\n", "before_files": [{"content": "\"\"\"Check live state management command.\"\"\"\n\nfrom datetime import datetime, timedelta, timezone\nimport json\nimport re\n\nfrom django.conf import settings\nfrom django.core.management.base import BaseCommand\n\nimport boto3\nfrom dateutil.parser import isoparse\n\nfrom marsha.core.defaults import RUNNING, STOPPING\nfrom marsha.core.models import Video\nfrom marsha.core.utils.medialive_utils import stop_live_channel\n\n\naws_credentials = {\n    \"aws_access_key_id\": settings.AWS_ACCESS_KEY_ID,\n    \"aws_secret_access_key\": settings.AWS_SECRET_ACCESS_KEY,\n    \"region_name\": settings.AWS_S3_REGION_NAME,\n}\n\n# Configure medialive client\nmedialive_client = boto3.client(\"medialive\", **aws_credentials)\n\n# Configure cloudwatch logs client\nlogs_client = boto3.client(\"logs\", **aws_credentials)\n\n\ndef parse_iso_date(iso_date):\n    \"\"\"Parse an iso 8601 date and return a datetime object.\"\"\"\n    return isoparse(iso_date)\n\n\ndef generate_expired_date():\n    \"\"\"Generate a datetime object 25 minutes in the past.\"\"\"\n    return datetime.now(tz=timezone.utc) - timedelta(minutes=25)\n\n\n# pylint: disable=too-many-locals\nclass Command(BaseCommand):\n    \"\"\"Check every live streaming running state on AWS.\"\"\"\n\n    help = (\n        \"Check activity on AWS for every live streaming running\"\n        \"and close them if there is not.\"\n    )\n\n    def handle(self, *args, **options):\n        \"\"\"Execute management command.\"\"\"\n        extract_message_pattern = (\n            r\"^(?P<ingestion_time>.*)\\t\"\n            r\"(?P<request_id>.*)\\t\"\n            r\"(?P<level>.*)\\t\"\n            r\"Received event:(?P<message>.*)$\"\n        )\n        extract_message_regex = re.compile(extract_message_pattern)\n\n        videos = Video.objects.filter(live_state=RUNNING)\n        for video in videos:\n            # For each running live video, we query cloudwatch on the current live\n            # to search messages having detail.alert_type set to `RTMP Has No Audio/Video`.\n            # This alert tell us there is no stream and the live can be stopped if the message is\n            # older than 25 minutes.\n            self.stdout.write(f\"Checking video {video.id}\")\n            live_info = video.live_info\n            logs = logs_client.filter_log_events(\n                logGroupName=live_info[\"cloudwatch\"][\"logGroupName\"],\n                startTime=int(int(video.live_info.get(\"started_at\")) * 1000),\n                filterPattern=(\n                    \"{\"\n                    '($.detail-type = \"MediaLive Channel Alert\") && '\n                    f\"($.resources[0] = \\\"{live_info['medialive']['channel']['arn']}\\\") &&\"\n                    '($.detail.alert_type = \"RTMP Has No Audio/Video\")'\n                    \"}\"\n                ),\n            )\n\n            pipelines_queue = {\"0\": [], \"1\": []}\n\n            for event in logs[\"events\"]:\n                # All events must be parsed to extract the JSON message. When an alert is added,\n                # the `alarm_state` property value is `SET` and when the alert is removed,\n                # the `alarm_state` property value is `CLEARED`.\n                # We have 2 pipelines, a live is over when the 2 pipeline have `SET` value\n                # in `alarm_state`.\n                # Alarm state act like a list with all the event history. It means a `CLEARED`\n                # event is related to a `SET` one. So we have to look over all events, put in\n                # a list all `SET` events and remove it if a `CLEARED` event is here. At the\n                # end if we have 2 `SET` events, the live has no activity and we have to check\n                # the time of the last `SET` event. If this time is older than 25 minutes we\n                # stop the channel.\n                log = extract_message_regex.match(event[\"message\"])\n                message = json.loads(log.group(\"message\"))\n\n                if message[\"detail\"][\"alarm_state\"] == \"SET\":\n                    pipelines_queue[message[\"detail\"][\"pipeline\"]].append(message)\n                else:\n                    pipelines_queue[message[\"detail\"][\"pipeline\"]].pop()\n\n            if len(pipelines_queue[\"0\"]) == 1 and len(pipelines_queue[\"1\"]) == 1:\n                # Both pipelines receive no stream, we have to check the more recent one\n                # and if the time is older than 25 minutes we stop the channel.\n                datetime_pipeline0 = parse_iso_date(pipelines_queue[\"0\"][0][\"time\"])\n                datetime_pipeline1 = parse_iso_date(pipelines_queue[\"1\"][0][\"time\"])\n                expired_date = generate_expired_date()\n\n                if (\n                    datetime_pipeline0 < expired_date\n                    or datetime_pipeline1 < expired_date\n                ):\n                    # Stop this channel\n                    self.stdout.write(\n                        f\"Stopping channel with id {live_info['medialive']['channel']['id']}\"\n                    )\n                    stop_live_channel(live_info[\"medialive\"][\"channel\"][\"id\"])\n\n                    video.live_state = STOPPING\n                    video.save()\n                    self.stdout.write(\"Channel stopped\")\n", "path": "src/backend/marsha/core/management/commands/check_live_state.py"}], "after_files": [{"content": "\"\"\"Check live state management command.\"\"\"\n\nfrom datetime import datetime, timedelta, timezone\nimport json\nimport re\n\nfrom django.conf import settings\nfrom django.core.management.base import BaseCommand\n\nimport boto3\nfrom dateutil.parser import isoparse\n\nfrom marsha.core.defaults import RUNNING, STOPPING\nfrom marsha.core.models import Video\nfrom marsha.core.utils.medialive_utils import stop_live_channel\n\n\naws_credentials = {\n    \"aws_access_key_id\": settings.AWS_ACCESS_KEY_ID,\n    \"aws_secret_access_key\": settings.AWS_SECRET_ACCESS_KEY,\n    \"region_name\": settings.AWS_S3_REGION_NAME,\n}\n\n# Configure medialive client\nmedialive_client = boto3.client(\"medialive\", **aws_credentials)\n\n# Configure cloudwatch logs client\nlogs_client = boto3.client(\"logs\", **aws_credentials)\n\n\ndef parse_iso_date(iso_date):\n    \"\"\"Parse an iso 8601 date and return a datetime object.\"\"\"\n    return isoparse(iso_date)\n\n\ndef generate_expired_date():\n    \"\"\"Generate a datetime object 25 minutes in the past.\"\"\"\n    return datetime.now(tz=timezone.utc) - timedelta(minutes=25)\n\n\n# pylint: disable=too-many-locals\nclass Command(BaseCommand):\n    \"\"\"Check every live streaming running state on AWS.\"\"\"\n\n    help = (\n        \"Check activity on AWS for every live streaming running\"\n        \"and close them if there is not.\"\n    )\n\n    def handle(self, *args, **options):\n        \"\"\"Execute management command.\"\"\"\n        extract_message_pattern = (\n            r\"^(?P<ingestion_time>.*)\\t\"\n            r\"(?P<request_id>.*)\\t\"\n            r\"(?P<level>.*)\\t\"\n            r\"Received event:(?P<message>.*)$\"\n        )\n        extract_message_regex = re.compile(extract_message_pattern)\n\n        videos = Video.objects.filter(live_state=RUNNING)\n        for video in videos:\n            # For each running live video, we query cloudwatch on the current live\n            # to search messages having detail.alert_type set to `RTMP Has No Audio/Video`.\n            # This alert tell us there is no stream and the live can be stopped if the message is\n            # older than 25 minutes.\n            self.stdout.write(f\"Checking video {video.id}\")\n            live_info = video.live_info\n            logs = logs_client.filter_log_events(\n                logGroupName=live_info[\"cloudwatch\"][\"logGroupName\"],\n                startTime=int((int(video.live_info.get(\"started_at\")) - 60) * 1000),\n                filterPattern=(\n                    \"{\"\n                    '($.detail-type = \"MediaLive Channel Alert\") && '\n                    f\"($.resources[0] = \\\"{live_info['medialive']['channel']['arn']}\\\") &&\"\n                    '($.detail.alert_type = \"RTMP Has No Audio/Video\")'\n                    \"}\"\n                ),\n            )\n\n            pipelines_queue = {\"0\": [], \"1\": []}\n\n            for event in logs[\"events\"]:\n                # All events must be parsed to extract the JSON message. When an alert is added,\n                # the `alarm_state` property value is `SET` and when the alert is removed,\n                # the `alarm_state` property value is `CLEARED`.\n                # We have 2 pipelines, a live is over when the 2 pipeline have `SET` value\n                # in `alarm_state`.\n                # Alarm state act like a list with all the event history. It means a `CLEARED`\n                # event is related to a `SET` one. So we have to look over all events, put in\n                # a list all `SET` events and remove it if a `CLEARED` event is here. At the\n                # end if we have 2 `SET` events, the live has no activity and we have to check\n                # the time of the last `SET` event. If this time is older than 25 minutes we\n                # stop the channel.\n                log = extract_message_regex.match(event[\"message\"])\n                message = json.loads(log.group(\"message\"))\n\n                if message[\"detail\"][\"alarm_state\"] == \"SET\":\n                    pipelines_queue[message[\"detail\"][\"pipeline\"]].append(message)\n                else:\n                    pipelines_queue[message[\"detail\"][\"pipeline\"]].pop()\n\n            if len(pipelines_queue[\"0\"]) == 1 and len(pipelines_queue[\"1\"]) == 1:\n                # Both pipelines receive no stream, we have to check the more recent one\n                # and if the time is older than 25 minutes we stop the channel.\n                datetime_pipeline0 = parse_iso_date(pipelines_queue[\"0\"][0][\"time\"])\n                datetime_pipeline1 = parse_iso_date(pipelines_queue[\"1\"][0][\"time\"])\n                expired_date = generate_expired_date()\n\n                if (\n                    datetime_pipeline0 < expired_date\n                    or datetime_pipeline1 < expired_date\n                ):\n                    # Stop this channel\n                    self.stdout.write(\n                        f\"Stopping channel with id {live_info['medialive']['channel']['id']}\"\n                    )\n                    stop_live_channel(live_info[\"medialive\"][\"channel\"][\"id\"])\n\n                    video.live_state = STOPPING\n                    video.save()\n                    self.stdout.write(\"Channel stopped\")\n", "path": "src/backend/marsha/core/management/commands/check_live_state.py"}]}