gh-102184: Test os.sync() only if "largefile" resource is enabled

Alexey Izbyshev · Alexey Izbyshev · commit 07adcb313107 · 2023-02-23T21:50:13.000+03:00
Calling `os.sync()` when the Linux page cache is large and full of dirty
pages and the storage device is slow can block the process in
"uninterruptible sleep" state for minutes, making the test run
unkillable even with SIGKILL. Avoid this by testing `os.sync()` only if
"largefile" resource is enabled.
diff --git a/Lib/test/test_posix.py b/Lib/test/test_posix.py
@@ -66,8 +66,12 @@ def testNoArgFunctions(self):
         NO_ARG_FUNCTIONS = [ "ctermid", "getcwd", "getcwdb", "uname",
                              "times", "getloadavg",
                              "getegid", "geteuid", "getgid", "getgroups",
-                             "getpid", "getpgrp", "getppid", "getuid", "sync",
+                             "getpid", "getpgrp", "getppid", "getuid",
                            ]
+        # gh-102184: Don't test sync() by default since it might cause heavy
+        # I/O and block for a long time.
+        if support.is_resource_enabled('largefile'):
+            NO_ARG_FUNCTIONS.append("sync")
 
         for name in NO_ARG_FUNCTIONS:
             posix_func = getattr(posix, name, None)
diff --git a/Misc/NEWS.d/next/Tests/2023-02-23-17-38-36.gh-issue-102184.W71J5G.rst b/Misc/NEWS.d/next/Tests/2023-02-23-17-38-36.gh-issue-102184.W71J5G.rst
@@ -0,0 +1 @@
+Test ``os.sync()`` only if "largefile" resource is enabled.

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	+Test ``os.sync()`` only if "largefile" resource is enabled.