https://github.com/python/cpython/commit/46f8a7bbdbb02cafaa00f7bb9478d3d27affc57a
commit: 46f8a7bbdbb02cafaa00f7bb9478d3d27affc57a
branch: main
author: Cody Maloney <[email protected]>
committer: vstinner <[email protected]>
date: 2024-11-22T15:55:32+01:00
summary:
gh-127076: Ignore memory mmap in FileIO testing (#127088)
`mmap`, `munmap`, and `mprotect` are used by CPython for memory
management, which may occur in the middle of the FileIO tests. The
system calls can also be used with files, so `strace` includes them
in its `%file` and `%desc` filters.
Filter out the `mmap` system calls related to memory allocation for the
file tests. Currently FileIO doesn't do `mmap` at all, so didn't add
code to track from `mmap` through `munmap` since it wouldn't be used.
For now if an `mmap` on a fd happens, the call will be included (which
may cause test to fail), and at that time support for tracking the
address throug `munmap` could be added.
files:
A Misc/NEWS.d/next/Tests/2024-11-20-18-49-01.gh-issue-127076.DHnXxo.rst
M Lib/test/support/strace_helper.py
M Lib/test/test_fileio.py
diff --git a/Lib/test/support/strace_helper.py
b/Lib/test/support/strace_helper.py
index 90281b47274299..eab16ea3e2889f 100644
--- a/Lib/test/support/strace_helper.py
+++ b/Lib/test/support/strace_helper.py
@@ -71,6 +71,27 @@ def sections(self):
return sections
+def _filter_memory_call(call):
+ # mmap can operate on a fd or "MAP_ANONYMOUS" which gives a block of
memory.
+ # Ignore "MAP_ANONYMOUS + the "MAP_ANON" alias.
+ if call.syscall == "mmap" and "MAP_ANON" in call.args[3]:
+ return True
+
+ if call.syscall in ("munmap", "mprotect"):
+ return True
+
+ return False
+
+
+def filter_memory(syscalls):
+ """Filter out memory allocation calls from File I/O calls.
+
+ Some calls (mmap, munmap, etc) can be used on files or to just get a block
+ of memory. Use this function to filter out the memory related calls from
+ other calls."""
+
+ return [call for call in syscalls if not _filter_memory_call(call)]
+
@support.requires_subprocess()
def strace_python(code, strace_flags, check=True):
@@ -93,8 +114,6 @@ def _make_error(reason, details):
"-c",
textwrap.dedent(code),
__run_using_command=[_strace_binary] + strace_flags,
- # Don't want to trace our JIT's own mmap and mprotect calls:
- PYTHON_JIT="0",
)
except OSError as err:
return _make_error("Caught OSError", err)
@@ -145,9 +164,14 @@ def get_events(code, strace_flags, prelude, cleanup):
return all_sections['code']
-def get_syscalls(code, strace_flags, prelude="", cleanup=""):
+def get_syscalls(code, strace_flags, prelude="", cleanup="",
+ ignore_memory=True):
"""Get the syscalls which a given chunk of python code generates"""
events = get_events(code, strace_flags, prelude=prelude, cleanup=cleanup)
+
+ if ignore_memory:
+ events = filter_memory(events)
+
return [ev.syscall for ev in events]
@@ -177,5 +201,5 @@ def requires_strace():
return unittest.skipUnless(_can_strace(), "Requires working strace")
-__all__ = ["get_events", "get_syscalls", "requires_strace", "strace_python",
- "StraceEvent", "StraceResult"]
+__all__ = ["filter_memory", "get_events", "get_syscalls", "requires_strace",
+ "strace_python", "StraceEvent", "StraceResult"]
diff --git a/Lib/test/test_fileio.py b/Lib/test/test_fileio.py
index d60aabcdf1ae22..e681417e15d34b 100644
--- a/Lib/test/test_fileio.py
+++ b/Lib/test/test_fileio.py
@@ -364,8 +364,7 @@ def testErrnoOnClosedReadinto(self, f):
@strace_helper.requires_strace()
def test_syscalls_read(self):
- """Check that the set of system calls produced by the I/O stack is what
- is expected for various read cases.
+ """Check set of system calls during common I/O patterns
It's expected as bits of the I/O implementation change, this will need
to change. The goal is to catch changes that unintentionally add
@@ -383,6 +382,11 @@ def check_readall(name, code, prelude="", cleanup="",
prelude=prelude,
cleanup=cleanup)
+ # Some system calls (ex. mmap) can be used for both File I/O
and
+ # memory allocation. Filter out the ones used for memory
+ # allocation.
+ syscalls = strace_helper.filter_memory(syscalls)
+
# The first call should be an open that returns a
# file descriptor (fd). Afer that calls may vary. Once the file
# is opened, check calls refer to it by fd as the filename
diff --git
a/Misc/NEWS.d/next/Tests/2024-11-20-18-49-01.gh-issue-127076.DHnXxo.rst
b/Misc/NEWS.d/next/Tests/2024-11-20-18-49-01.gh-issue-127076.DHnXxo.rst
new file mode 100644
index 00000000000000..39323604bbef56
--- /dev/null
+++ b/Misc/NEWS.d/next/Tests/2024-11-20-18-49-01.gh-issue-127076.DHnXxo.rst
@@ -0,0 +1,2 @@
+Filter out memory-related ``mmap``, ``munmap``, and ``mprotect`` calls from
+file-related ones when testing :mod:`io` behavior using strace.
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