Issue #14107: test: Fix a deadlock involving the memory watchdog thread.
diff --git a/Lib/test/support.py b/Lib/test/support.py
index 47b94ca..c384222 100644
--- a/Lib/test/support.py
+++ b/Lib/test/support.py
@@ -45,6 +45,11 @@
except ImportError:
zlib = None
+try:
+ import fcntl
+except ImportError:
+ fcntl = None
+
__all__ = [
"Error", "TestFailed", "ResourceDenied", "import_module",
"verbose", "use_resources", "max_memuse", "record_original_stdout",
@@ -1184,6 +1189,11 @@
sys.stderr.flush()
return
pipe_fd, wfd = os.pipe()
+ # set the write end of the pipe non-blocking to avoid blocking the
+ # watchdog thread when the consumer doesn't drain the pipe fast enough
+ if fcntl:
+ flags = fcntl.fcntl(wfd, fcntl.F_GETFL)
+ fcntl.fcntl(wfd, fcntl.F_SETFL, flags|os.O_NONBLOCK)
# _file_watchdog() doesn't take the GIL in its child thread, and
# therefore collects statistics timely
faulthandler._file_watchdog(rfd, wfd, 1.0)