Allow the pool to grow

diff --git a/psycopg3/psycopg3/pool.py b/psycopg3/psycopg3/pool.py
index ce225f96ad1b7e1978b9191aedf539fb21ad612c..1e4fdc4bc34aa645955c7863ef567aeb7d648477 100644 (file)
--- a/psycopg3/psycopg3/pool.py
+++ b/psycopg3/psycopg3/pool.py
@@ -130,12 +130,18 @@ class ConnectionPool:
             pos: Optional[WaitingClient] = None
             if self._pool:
                 # Take a connection ready out of the pool
-                conn = self._pool.pop(-1)
+                conn = self._pool.pop(-1)[0]
             else:
                 # No connection available: put the client in the waiting queue
                 pos = WaitingClient()
                 self._waiting.append(pos)
 
+                # If there is space for the pool to grow, let's do it
+                if self._nconns < self.maxconn:
+                    logger.debug("growing pool %s", self.name)
+                    self._nconns += 1
+                    self.add_task(AddConnection(self))
+
         # If we are in the waiting queue, wait to be assigned a connection
         # (outside the critical section, so only the waiting client is locked)
         if pos:

diff --git a/tests/test_pool.py b/tests/test_pool.py
index a7feed78ec6e0a3bfd3e28e88afc8e437209c42e..72bb5c2b0ac4457747ecb6697815ee58fce55d5c 100644 (file)
--- a/tests/test_pool.py
+++ b/tests/test_pool.py
@@ -6,8 +6,8 @@ from threading import Thread
 import pytest
 
 import psycopg3
-from psycopg3.pq import TransactionStatus
 from psycopg3 import pool
+from psycopg3.pq import TransactionStatus
 
 
 def test_minconn_maxconn(dsn):
@@ -274,8 +274,7 @@ def test_del_no_warning(dsn, recwarn):
     with p.connection() as conn:
         conn.execute("select 1")
 
-    while len(p._pool) < p.minconn:
-        sleep(0.01)
+    wait_pool_full(p)
 
     ref = weakref.ref(p)
     del p
@@ -336,3 +335,53 @@ def test_closed_queue(dsn):
     t1.join()
     t2.join()
     assert len(success) == 2
+
+
+@pytest.mark.slow
+def test_grow(dsn, monkeypatch):
+    p = pool.ConnectionPool(dsn, minconn=2, maxconn=4, num_workers=3)
+    wait_pool_full(p)
+    delay_connection(monkeypatch, 0.1)
+    ts = []
+    results = []
+
+    def worker(n):
+        t0 = time()
+        with p.connection() as conn:
+            conn.execute("select 1 from pg_sleep(0.2)")
+        t1 = time()
+        results.append((n, t1 - t0))
+
+    for i in range(6):
+        t = Thread(target=worker, args=(i,))
+        t.start()
+        ts.append(t)
+
+    for t in ts:
+        t.join()
+
+    deltas = [0.2, 0.2, 0.3, 0.3, 0.4, 0.4]
+    for (_, got), want in zip(results, deltas):
+        assert got == pytest.approx(want, 0.1)
+
+
+def delay_connection(monkeypatch, sec):
+    """
+    Return a _connect_gen function delayed by the amount of seconds
+    """
+    connect_gen_orig = psycopg3.Connection._connect_gen
+
+    def connect_gen_delayed(*args, **kwargs):
+        psycopg3.pool.logger.debug("delaying connection")
+        sleep(sec)
+        rv = yield from connect_gen_orig(*args, **kwargs)
+        return rv
+
+    monkeypatch.setattr(
+        psycopg3.Connection, "_connect_gen", connect_gen_delayed
+    )
+
+
+def wait_pool_full(pool):
+    while len(pool._pool) < pool.minconn:
+        sleep(0.01)