From 05ebb009b542a9e9256b3b9a0fa34ccc68f71838 Mon Sep 17 00:00:00 2001
From: memsharded <james@conan.io>
Date: Wed, 12 Nov 2025 23:25:56 +0100
Subject: [PATCH] propose stress testing for concurrency primitives

---
 test/unittests/util/test_filelocks.py | 48 +++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)
 create mode 100644 test/unittests/util/test_filelocks.py

diff --git a/test/unittests/util/test_filelocks.py b/test/unittests/util/test_filelocks.py
new file mode 100644
index 00000000000..ce610b97cbb
--- /dev/null
+++ b/test/unittests/util/test_filelocks.py
@@ -0,0 +1,48 @@
+import os
+import tempfile
+import time
+from multiprocessing import Process
+from string import ascii_lowercase
+
+import fasteners
+
+tmpf = os.path.join(tempfile.gettempdir(), "conan_test", "filelocks")
+datafile = os.path.join(tmpf, "data.txt")
+lock = os.path.join(tmpf, "data.txt.lock")
+
+
+def _mywriter():
+    for c in ascii_lowercase:
+        with fasteners.InterProcessLock(lock):
+            open(datafile, "w").write(c * 50)
+            for _ in range(4):
+                time.sleep(0.1)  # slow writes to cause race conditions
+                open(datafile, "a").write(c * 50)
+        time.sleep(0.1)
+
+
+def _myreader():
+    while True:
+        with fasteners.InterProcessLock(lock):
+            contents = open(datafile, "r").read()
+            d = contents[0]
+            assert contents == d * 250, f"{len(contents)}: {contents}"
+            if d == "z":
+                break
+        time.sleep(0.01)
+
+
+def test_simple_mutex():
+    os.makedirs(os.path.dirname(datafile), exist_ok=True)
+    open(datafile, "w+").write("a" * 250)
+
+    pread = Process(target=_myreader)
+    pread.start()
+    pwrite = Process(target=_mywriter)
+    pwrite.start()
+
+    pread.join()
+    if pread.exitcode:
+        pwrite.terminate()
+        raise Exception("pread failed")
+    pwrite.join()