Mysql Db connection error

[sanjoshi]

Hi,

I am trying to connect to Mysql database from caravel. But I keep getting these errors intermittently.

1. SIGPIPE: writing to a closed pipe/socket/fd (probably the client disconnected) !!!
2. OperationalError: (_mysql_exceptions.OperationalError) (2006, 'MySQL server has gone away')
3. ERROR:sqlalchemy.pool.QueuePool:Exception during reset or similar

Is there a way to handle these issues?

This is the configuration that I am using for SQLAlchemy
SQLALCHEMY_POOL_SIZE = 10
SQLALCHEMY_POOL_TIMEOUT = 10
SQLALCHEMY_POOL_RECYCLE = 100
SQLALCHEMY_DATABASE_URI = 'mysql+mysqldb://user:pwd@host:port/db'

Please help.
Thanks in advance.

[nickrox]

I think this issue is on the mysql side.
Possible causes are mentioned in the documentation http://dev.mysql.com/doc/refman/5.7/en/gone-away.html

Please see if it helps.

[sanjoshi]

How/Where does caravel try to make the mysql db connection? I am unable to find where it tries to make the connection.
I can see the db.session but not 'connect'.

[mistercrunch]

it's handled by the flask-sqlalchemy package

[sanjoshi]

Hi @mistercrunch How can I handle it? I have tried different configurations but it is still not working.
The mysql db timeout is 600s. So I have given my SQLALCHEMY_POOL_RECYCLE = 100.

Is there a better way to handle it?

Thanks

[sanjoshi]

Hi..
Also please let me know what is this being used for?
CARAVEL_WEBSERVER_TIMEOUT

Is this why we could be facing these issues?

[xrmx]

@sanjoshi maybe that's the same mysql config issue as #457

[bkyryliuk]

@sanjoshi - feel free to reopen if the issue is not resolved.
Tweaking the max_allowed_packet in mysql config helped in the #457