Monkeypatch my asyncio fix until 0.0.20 releases.

monkeypatch_aiomysql.py

import asyncio
from aiomysql.pool import Pool, connect


def patch_pool():
    """Monkey patch until aiomysql fixes this bug"""
    Pool._fill_free_pool = _fill_free_pool


# Only change from aiomysql's implementation is to check the reader's exception in addition to at_eof.
@asyncio.coroutine
def _fill_free_pool(self, override_min):
    # iterate over free connections and remove timeouted ones
    free_size = len(self._free)
    n = 0
    while n < free_size:
        conn = self._free[-1]
        if conn._reader.at_eof() or conn._reader.exception():  # MONKEY PATCH LINE
            self._free.pop()
            conn.close()

        elif (self._recycle > -1 and
              self._loop.time() - conn.last_usage > self._recycle):
            self._free.pop()
            conn.close()

        else:
            self._free.rotate()
        n += 1

    while self.size < self.minsize:
        self._acquiring += 1
        try:
            conn = yield from connect(echo=self._echo, loop=self._loop,
                                      **self._conn_kwargs)
            # raise exception if pool is closing
            self._free.append(conn)
            self._cond.notify()
        finally:
            self._acquiring -= 1
    if self._free:
        return

    if override_min and self.size < self.maxsize:
        self._acquiring += 1
        try:
            conn = yield from connect(echo=self._echo, loop=self._loop,
                                      **self._conn_kwargs)
            # raise exception if pool is closing
            self._free.append(conn)
            self._cond.notify()
        finally:
            self._acquiring -= 1