Fix pool maxsize unlimited (#426)

* fix: allow pool.maxsize to be unlimited

* tests: add test for unlimited pool size

* add test for pool minsize=1 maxsize=0

* Skip minsize validation for unlimited size pools

* Make maxsize property optional

* add changelog note

Co-authored-by: Richard Schwab <[email protected]>

CHANGES.txt

@@ -17,6 +17,7 @@ To be included in 1.0.0 (unreleased)
 * Support PyMySQL up to version 1.0.2 #643
 * Bump minimal PyMySQL version to 1.0.0 #713
 * Align % formatting in Cursor.executemany() with Cursor.execute(), literal % now need to be doubled in Cursor.executemany() #714
+* Fixed unlimited Pool size not working, this is now working as documented by passing maxsize=0 to create_pool #119
 
 
 0.0.22 (2021-11-14)

aiomysql/pool.py

@@ -36,13 +36,13 @@ class Pool(asyncio.AbstractServer):
     def __init__(self, minsize, maxsize, echo, pool_recycle, loop, **kwargs):
         if minsize < 0:
             raise ValueError("minsize should be zero or greater")
-        if maxsize < minsize:
+        if maxsize < minsize and maxsize != 0:
             raise ValueError("maxsize should be not less than minsize")
         self._minsize = minsize
         self._loop = loop
         self._conn_kwargs = kwargs
         self._acquiring = 0
-        self._free = collections.deque(maxlen=maxsize)
+        self._free = collections.deque(maxlen=maxsize or None)
         self._cond = asyncio.Condition()
         self._used = set()
         self._terminated = set()
@@ -182,7 +182,7 @@ async def _fill_free_pool(self, override_min):
         if self._free:
             return
 
-        if override_min and self.size < self.maxsize:
+        if override_min and (not self.maxsize or self.size < self.maxsize):
             self._acquiring += 1
             try:
                 conn = await connect(echo=self._echo, loop=self._loop,

tests/test_pool.py

@@ -538,3 +538,21 @@ async def test_pool_drops_connection_with_exception(pool_creator, loop):
     async with pool.get() as conn:
         cur = await conn.cursor()
         await cur.execute('SELECT 1;')
+
+
+@pytest.mark.run_loop
+async def test_pool_maxsize_unlimited(pool_creator, loop):
+    pool = await pool_creator(minsize=0, maxsize=0)
+
+    async with pool.acquire() as conn:
+        cur = await conn.cursor()
+        await cur.execute('SELECT 1;')
+
+
+@pytest.mark.run_loop
+async def test_pool_maxsize_unlimited_minsize_1(pool_creator, loop):
+    pool = await pool_creator(minsize=1, maxsize=0)
+
+    async with pool.acquire() as conn:
+        cur = await conn.cursor()
+        await cur.execute('SELECT 1;')