<h3 dir="auto">Apache Airflow version</h3>
<p dir="auto">2.1.3 (latest released)</p>
<h3 dir="auto">Operating System</h3>
<p dir="auto">Debian</p>
<h3 dir="auto">Versions of Apache Airflow Providers</h3>
<p dir="auto"><em>No response</em></p>
<h3 dir="auto">Deployment</h3>
<p dir="auto">Other Docker-based deployment</p>
<h3 dir="auto">Deployment details</h3>
<p dir="auto">Custom docker image on k8s</p>
<h3 dir="auto">What happened</h3>
<p dir="auto">New dag version was written in same named dag. The only difference was one of specified tags got changed in case, for ex. "test" to "Test". With huge amount of dags this causes scheduler immediately to crash due to constraint violation.</p>
<h3 dir="auto">What you expected to happen</h3>
<p dir="auto">Tags are refreshed correctly without crash of scheduler.</p>
<h3 dir="auto">How to reproduce</h3>
<ol dir="auto">
<li>Create dag with tags in running airflow cluster</li>
<li>Update dag with change of case of one of tags for ex. "test" to "Test"</li>
<li>Watch scheduler crash continuously</li>
</ol>
<h3 dir="auto">Anything else</h3>
<p dir="auto">Alternative option is to make tags case sensitive...</p>
<h3 dir="auto">Are you willing to submit PR?</h3>
<ul class="contains-task-list">
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> Yes I am willing to submit a PR!</li>
</ul>
<h3 dir="auto">Code of Conduct</h3>
<ul class="contains-task-list">
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I agree to follow this project's <a href="https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md">Code of Conduct</a></li>
</ul>
<p dir="auto">Apache Airflow version: v1109<br>
executor: CeleryExecutor</p>
<p dir="auto">some time the scheduler create many sub scheduler process. When this happens, the CPU usage of these sub schduler process is at 99%, and then i can see web ui appear：<strong>The scheduler does not appear to be running. Last heartbeat was received xxx ago.The DAGs list may not update, and new tasks will not be scheduled.</strong></p>
<p dir="auto">job_heartbeat_sec = 5<br>
scheduler_heartbeat_sec = 5<br>
run_duration = -1<br>
num_runs = -1<br>
processor_poll_interval = 1<br>
min_file_process_interval = 30</p>
<p dir="auto">here is some log i mark，but  the scheduler log had no error</p>
<p dir="auto">etl   23905 12016  0 Oct17 ?        00:00:00 /bin/bash -c source /usr/soft/anaconda3/bin/activate etl_airflow_v1109 &amp;&amp; airflow scheduler<br>
etl   23908 23905  1 Oct17 ?        03:13:04 /root/etl_airflow_v1109/bin/python /root/etl_airflow_v1109/bin/airflow scheduler<br>
etl   23947 23908  1 Oct17 ?        02:40:24 airflow scheduler -- DagFileProcessorManager<br>
etl   30570 23908 99 03:07 ?        00:07:22 /root/etl_airflow_v1109/bin/python /root/etl_airflow_v1109/bin/airflow scheduler<br>
etl   30573 23908 99 03:07 ?        00:07:22 /root/etl_airflow_v1109/bin/python /root/etl_airflow_v1109/bin/airflow scheduler<br>
etl   30574 23908 99 03:07 ?        00:07:22 /root/etl_airflow_v1109/bin/python /root/etl_airflow_v1109/bin/airflow scheduler<br>
etl   30575 23908 99 03:07 ?        00:07:22 /root/etl_airflow_v1109/bin/python /root/etl_airflow_v1109/bin/airflow scheduler<br>
etl   30576 23908 99 03:07 ?        00:07:22 /root/etl_airflow_v1109/bin/python /root/etl_airflow_v1109/bin/airflow scheduler<br>
etl   30577 23908 99 03:07 ?        00:07:22 /root/etl_airflow_v1109/bin/python /root/etl_airflow_v1109/bin/airflow scheduler<br>
etl   30578 23908 99 03:07 ?        00:07:22 /root/etl_airflow_v1109/bin/python /root/etl_airflow_v1109/bin/airflow scheduler<br>
etl   30579 23908 99 03:07 ?        00:07:22 /root/etl_airflow_v1109/bin/python /root/etl_airflow_v1109/bin/airflow scheduler<br>
etl   30580 23908 99 03:07 ?        00:07:22 /root/etl_airflow_v1109/bin/python /root/etl_airflow_v1109/bin/airflow scheduler<br>
etl   30581 23908 99 03:07 ?        00:07:22 /root/etl_airflow_v1109/bin/python /root/etl_airflow_v1109/bin/airflow scheduler<br>
etl   30583 23908 99 03:07 ?        00:07:22 /root/etl_airflow_v1109/bin/python /root/etl_airflow_v1109/bin/airflow scheduler</p>
<p dir="auto">Please help. I would be happy to provide any other information needed</p>