[BUG] InterfaceError: (0, '')

[xunto]

Traceback (most recent call last):
  File "/usr/local/lib/python3.6/dist-packages/flask/app.py", line 1982, in wsgi_app
    response = self.full_dispatch_request()
  File "/usr/local/lib/python3.6/dist-packages/flask/app.py", line 1614, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/usr/local/lib/python3.6/dist-packages/flask/app.py", line 1517, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/usr/local/lib/python3.6/dist-packages/flask/_compat.py", line 33, in reraise
    raise value
  File "/usr/local/lib/python3.6/dist-packages/flask/app.py", line 1612, in full_dispatch_request
    rv = self.dispatch_request()
  File "/usr/local/lib/python3.6/dist-packages/flask/app.py", line 1598, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "<string>", line 2, in application_list
  File "/usr/local/lib/python3.6/dist-packages/pony/orm/core.py", line 423, in new_func
    finally: db_session.__exit__(exc_type, exc, tb)
  File "/usr/local/lib/python3.6/dist-packages/pony/orm/core.py", line 397, in __exit__
    else: rollback()
  File "<string>", line 2, in rollback
  File "/usr/local/lib/python3.6/dist-packages/pony/utils/utils.py", line 58, in cut_traceback
    return func(*args, **kwargs)
  File "/usr/local/lib/python3.6/dist-packages/pony/orm/core.py", line 326, in rollback
    transact_reraise(RollbackException, exceptions)
  File "/usr/local/lib/python3.6/dist-packages/pony/orm/core.py", line 283, in transact_reraise
    reraise(exc_class, new_exc, tb)
  File "/usr/local/lib/python3.6/dist-packages/pony/utils/utils.py", line 85, in reraise
    try: raise exc.with_traceback(tb)
  File "/usr/local/lib/python3.6/dist-packages/pony/orm/core.py", line 323, in rollback
    try: cache.rollback()
  File "/usr/local/lib/python3.6/dist-packages/pony/orm/core.py", line 1559, in rollback
    cache.close(rollback=True)
  File "/usr/local/lib/python3.6/dist-packages/pony/orm/core.py", line 1573, in close
    try: provider.rollback(connection, cache)
  File "<string>", line 2, in rollback
  File "/usr/local/lib/python3.6/dist-packages/pony/orm/dbapiprovider.py", line 59, in wrap_dbapi_exceptions
    raise InterfaceError(e)
pony.orm.core.RollbackException: InterfaceError: (0, '')

Looks like it happen when you do nothing to db for some time and then do something. For example, when script waits for http request and when it get it, pony throws the exception. If you do another request after that, everything will be ok.

I had this issue with aiohttp (but i thought that it's related to threadpool that i used) and flask.

[xunto]

pony version is 0.7.1

[xunto]

Database... I had this issue with mysql.

[Achillesxu]

i got the same error, someone find some way to solve it?

[xunto]

No. But I found out that it is related to mysql driver and global cursor usage.

[Achillesxu]

how to test this? i planed to switch to sqlalchemy

[Achillesxu]

incredibly, i replace the PyMySQl using the MySQL-python, the bug had gone!

[xunto]

@Achillesxu could you provide some code? This bug driving me crazy! Did you replace mysql driver? I didn't know there is such option. :D

[xunto]

I mean that I didn't know there is option to choose specific driver. What should I do? Just remove PyMySQl and install MySQL-python?

[xunto]

Meh, MySQL-python doesn't seem to work with python3.6. :(

[kozlovsky]

Hi @xunto , I think this issue is related to #219. You can check Pony version from GitHub, the bug should be already fixed in 1146ff1. Before the fix, RollbackException masked the real problem caused by database driver, now you should be able to see the real reason for the error. I plan to make new Pony release at Monday with this fix.

[xunto]

@kozlovsky wow, new release is good news. I'll check today if problem is fixed on the lastest commit of the orm branch and will let you know.

[xunto]

pony.orm.dbapiprovider.OperationalError: (2013, 'Lost connection to MySQL server during query')

Now I caught this. Is it something with Mysql configuration or what?

[kozlovsky]

I think probably so. Some of the following links may help:
r-dbi/RMySQL#190
https://stackoverflow.com/questions/6516943/lost-connection-to-mysql-server-during-query
https://serverfault.com/questions/739137/lost-connection-to-mysql-server-during-query

If you discover a reason for the issue, then please leave a comment here for other MySQL users.

[xunto]

Oh, that legacy. :) But it doesn't look like there are such problems with php app.

[Achillesxu]

Pony tries to use the MySQLdb driver for working with MySQL. If this module cannot be imported, Pony tries to use pymysql. See the MySQLdb and pymysql documentation for more information regarding these drivers. from 'https://docs.ponyorm.com/api_reference.html#mysql'
i just pip install MySQL-python, restart my program, and uninstall PyMySQL, my error dont occur again.
my error is that multiprocess(python 2.7 using PyMySQL driver) write records to mysql(5.5) database, then commit error occur frequently, the error is same as that you encounter.

[xunto]

max_connections = 400
max_allowed_packet = 1G
wait_timeout = 31536000

I'm not the one the who is administrating database but asked this man to give me that. This configuration seem to solve the problem.

[xunto]

I think everything is OK now. But I have more mysql related problems! I close this one for now.