python - SQLAlchemy error MySQL server has gone away -

error operationalerror: (operationalerror) (2006, 'mysql server has gone away') i'm received error when coded project on flask, cant understand why error.

i have code (yeah, if code small , executing fast, no errors) \

db_engine = create_engine('mysql://root@127.0.0.1/mind?charset=utf8', pool_size=10, pool_recycle=7200) base.metadata.create_all(db_engine)  session = sessionmaker(bind=db_engine, autoflush=true) session = scoped_session(session) session = session()  # there many classes , functions  session.close() 

and code returns me error 'mysql server has gone away', return after time, when use pauses in script.

mysql use openserver.ru (it's web server such wamp).

thanks..

sqlalchemy has great write-up on how can use pinging pessimistic connection's freshness:

http://docs.sqlalchemy.org/en/latest/core/pooling.html#disconnect-handling-pessimistic

from there,

from sqlalchemy import exc sqlalchemy import event sqlalchemy.pool import pool  @event.listens_for(pool, "checkout") def ping_connection(dbapi_connection, connection_record, connection_proxy):     cursor = dbapi_connection.cursor()     try:         cursor.execute("select 1")     except:         # optional - dispose whole pool         # instead of invalidating 1 @ time         # connection_proxy._pool.dispose()          # raise disconnectionerror - pool try         # connecting again 3 times before raising.         raise exc.disconnectionerror()     cursor.close() 

and test make sure above works:

from sqlalchemy import create_engine e = create_engine("mysql://scott:tiger@localhost/test", echo_pool=true) c1 = e.connect() c2 = e.connect() c3 = e.connect() c1.close() c2.close() c3.close()  # pool size three.  print "restart server" raw_input()  in xrange(10):     c = e.connect()     print c.execute("select 1").fetchall()     c.close()