[Sqlalchemy-tickets] Issue #4028: move can't connect handling outside of "except Empty" (zzzeek/sqlalchemy)

[Michael B. <iss...@bi...>]

New issue 4028: move can't connect handling outside of "except Empty"
https://bitbucket.org/zzzeek/sqlalchemy/issues/4028/move-cant-connect-handling-outside-of

Michael Bayer:

When a pool can't connect to the DB, Python 3 does this:


```
#!

Traceback (most recent call last):
  File "/usr/local/lib64/python3.5/site-packages/sqlalchemy/pool.py", line 1122, in _do_get
    return self._pool.get(wait, self._timeout)
  File "/usr/local/lib64/python3.5/site-packages/sqlalchemy/util/queue.py", line 145, in get
    raise Empty
sqlalchemy.util.queue.Empty
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
  File "/usr/local/lib64/python3.5/site-packages/sqlalchemy/engine/base.py", line 2147, in _wrap_pool_connect
    return fn()
  File "/usr/local/lib64/python3.5/site-packages/sqlalchemy/pool.py", line 328, in unique_connection
    return _ConnectionFairy._checkout(self)
  File "/usr/local/lib64/python3.5/site-packages/sqlalchemy/pool.py", line 766, in _checkout
    fairy = _ConnectionRecord.checkout(pool)
  File "/usr/local/lib64/python3.5/site-packages/sqlalchemy/pool.py", line 516, in checkout
    rec = pool._do_get()
  File "/usr/local/lib64/python3.5/site-packages/sqlalchemy/pool.py", line 1138, in _do_get
    self._dec_overflow()
  File "/usr/local/lib64/python3.5/site-packages/sqlalchemy/util/langhelpers.py", line 66, in __exit__
    compat.reraise(exc_type, exc_value, exc_tb)
  File "/usr/local/lib64/python3.5/site-packages/sqlalchemy/util/compat.py", line 187, in reraise
    raise value
  File "/usr/local/lib64/python3.5/site-packages/sqlalchemy/pool.py", line 1135, in _do_get
    return self._create_connection()
  File "/usr/local/lib64/python3.5/site-packages/sqlalchemy/pool.py", line 333, in _create_connection
    return _ConnectionRecord(self)
  File "/usr/local/lib64/python3.5/site-packages/sqlalchemy/pool.py", line 461, in __init__
    self.__connect(first_connect_check=True)
  File "/usr/local/lib64/python3.5/site-packages/sqlalchemy/pool.py", line 651, in __connect
    connection = pool._invoke_creator(self)
  File "/usr/local/lib64/python3.5/site-packages/sqlalchemy/engine/strategies.py", line 105, in connect
    return dialect.connect(*cargs, **cparams)
  File "/usr/local/lib64/python3.5/site-packages/sqlalchemy/engine/default.py", line 393, in connect
    return self.dbapi.connect(*cargs, **cparams)
  File "/usr/local/lib64/python3.5/site-packages/MySQLdb/__init__.py", line 81, in Connect
    return Connection(*args, **kwargs)
  File "/usr/local/lib64/python3.5/site-packages/MySQLdb/connections.py", line 191, in __init__
    super(Connection, self).__init__(*args, **kwargs2)
_mysql_exceptions.OperationalError: (2003, "Can't connect to MySQL server on 'dbhost_obviously' (4)")
```


this confuses everyone.  move the handling outside of Empty.