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From Nadeem Ahmed Nazeer <>
Subject airflow scheduler error
Date Thu, 21 Jul 2016 00:18:00 GMT

My airflow scheduler seems to be getting stuck due to an error.

>From scheduler logs,

HTTPError: HTTP 502: socket error
Logged from file, line 574

Looks like it happens when the scheduler is trying to get the list of
queued tasks from the metadata database. There are no errors being reported
on the DB side though. The metadata database is a mysql RDS instance
running on aws.

I will have to restart the scheduler service manually multiple times to get
it going before it gets stuck again. It appears that the scheduler has some
trouble polling the db occasionally. But, this is only error i see from the

Below is my config,

sql_alchemy_pool_recycle = 3600
parallelism = 32
celeryd_concurrency = 4
scheduler_heartbeat_sec = 120

Has someone faced this similar error with the scheduler or metadata db?
Please share any inputs that could help me resolve this issue.

Is there an optimal configuration for the scheduler that i can put in
airflow.cfg to enable the scheduler run smoothly and be fast? Please share
the scheduler related configs if you have one that is running without


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