From: Daniele Varrazzo <daniele.varrazzo@gmail.com>
Date: Sun, 9 Apr 2023 18:59:55 +0000 (+0200)
Subject: fix: don't use select as wait function if possible
X-Git-Tag: 3.1.9~6
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1c11db3ebd52c300f0445a721be7971b40e15227;p=thirdparty%2Fpsycopg.git

fix: don't use select as wait function if possible

select is marginally faster than others, but has the limitation of not
allowing FD > 1024, so it is not a good default.

If people need performance, they will use wait_c anyway, which is based
on poll, and doesn't have the limitation.
---

diff --git a/psycopg/psycopg/waiting.py b/psycopg/psycopg/waiting.py
index 7abfc58a9..2c4a10fd1 100644
--- a/psycopg/psycopg/waiting.py
+++ b/psycopg/psycopg/waiting.py
@@ -318,14 +318,7 @@ elif selectors.DefaultSelector is getattr(selectors, "SelectSelector", None):
     wait = wait_select
 
 elif selectors.DefaultSelector is getattr(selectors, "EpollSelector", None):
-    # NOTE: select seems more performing than epoll. It is admittedly unlikely
-    # that a platform has epoll but not select, so maybe we could kill
-    # wait_epoll altogether(). More testing to do.
-    wait = wait_select if hasattr(selectors, "SelectSelector") else wait_epoll
-
-elif selectors.DefaultSelector is getattr(selectors, "KqueueSelector", None):
-    # wait_select is faster than wait_selector, probably because of less overhead
-    wait = wait_select if hasattr(selectors, "SelectSelector") else wait_selector
+    wait = wait_epoll
 
 else:
     wait = wait_selector
diff --git a/tests/test_waiting.py b/tests/test_waiting.py
index f5ece29e5..bcfd348c2 100644
--- a/tests/test_waiting.py
+++ b/tests/test_waiting.py
@@ -83,9 +83,9 @@ def test_wait_bad(pgconn, waitfn):
 @pytest.mark.skipif(
     "sys.platform == 'win32'", reason="win32 works ok, but FDs are mysterious"
 )
-@pytest.mark.parametrize("waitfn", waitfns)
-def test_wait_large_fd(dsn, waitfn):
-    waitfn = getattr(waiting, waitfn)
+@pytest.mark.parametrize("fname", waitfns)
+def test_wait_large_fd(dsn, fname):
+    waitfn = getattr(waiting, fname)
 
     files = []
     try:
@@ -100,7 +100,7 @@ def test_wait_large_fd(dsn, waitfn):
             assert pgconn.socket > 1024
             pgconn.send_query(b"select 1")
             gen = generators.execute(pgconn)
-            if waitfn is waiting.wait_select:
+            if fname == "wait_select":
                 with pytest.raises(ValueError):
                     waitfn(gen, pgconn.socket)
             else: