`test_is_python_process_non_python_subprocess` always times out when `sleep` is a multicall binary (Alpine/BusyBox, RHEL UBI9)
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還沒有人認領這個 Issue。
評估
- 難度
- 2/5
- 預估耗時
- 1-3 小時
- 新手友好度
- 76/100
- Issue 類型
- 缺陷
- 描述清晰度
- 描述清楚
- 活躍度
- 活躍
- 技術堆疊
- linux, python
研究方向
閱讀 Lib/test/test_profiling/test_sampling_profiler/test_children.py,尤其是 _wait_for_process_exec() 和 test_is_python_process_non_python_subprocess。Issue 包含一項提議的檢查,用來偵測子程序的可執行檔是否變更,不論其名稱為何。更新 helper 及其呼叫處,接著在 Linux 上執行指定的測試;使用 multicall sleep 二進位檔和一般二進位檔時,測試都應通過。
由索引模型根據 Issue 內容生成。
描述
Bug report
Bug description:
The fix for gh-159534 (GH-160028, backported to 3.15 in GH-160080) makes test_is_python_process_non_python_subprocess fail every time on systems where sleep is provided by a multicall binary. That includes the Alpine buildbots, where the original gh-159534 failure was found:
FAIL: test_is_python_process_non_python_subprocess (test.test_profiling.test_sampling_profiler.test_children.TestIsPythonProcess.test_is_python_process_non_python_subprocess)
Test that a non-Python subprocess is not detected as Python.
----------------------------------------------------------------------
Traceback (most recent call last):
File ".../Lib/test/test_profiling/test_sampling_profiler/test_children.py", line 628, in test_is_python_process_non_python_subprocess
_wait_for_process_exec(proc, "sleep", SHORT_TIMEOUT)
File ".../Lib/test/test_profiling/test_sampling_profiler/test_children.py", line 91, in _wait_for_process_exec
for _ in sleeping_retry(timeout, max_delay=0.1):
File ".../Lib/test/support/__init__.py", line 2779, in sleeping_retry
for _ in busy_retry(timeout, err_msg, error=error):
File ".../Lib/test/support/__init__.py", line 2749, in busy_retry
raise AssertionError(msg)
AssertionError: timeout (45.1 seconds)
Buildbots
AMD64 Alpine Linux NoGIL 3.x:
- build 3444 (before GH-160028): the original intermittent failure,
True is not false. - build 3445 (first build with GH-160028):
timeout (45.1 seconds). Every build since fails the same way, e.g. build 3523.
AMD64 Alpine Linux 3.15:
- build 800 (before GH-160080): only
test_lazy_importfails. - build 815 (first build with GH-160080) and every build since, including build 851 just before v3.15.2 was tagged: this test fails too.
This failure is separate from the test_lazy_import crash on Alpine (gh-159535). The Alpine builders will stay red after that crash is fixed.
Cause
The new _wait_for_process_exec() helper waits until os.path.basename(os.readlink(f"/proc/{pid}/exe")) == "sleep". When sleep is a multicall binary, /proc/{pid}/exe points to the multicall binary instead:
| System | /usr/bin/sleep or /bin/sleep |
/proc/{pid}/exe of a running sleep |
|---|---|---|
| Alpine 3.24 (BusyBox) | symlink to /bin/busybox |
/bin/busybox |
RHEL UBI9 (coreutils-single, the image default) |
shebang script #!/usr/bin/coreutils --coreutils-prog-shebang=sleep |
/usr/bin/coreutils |
RHEL UBI9 after dnf swap coreutils-single coreutils |
regular binary | /usr/bin/sleep |
The condition never becomes true, so the test always times out.
Reproducer, tested in python:3-alpine and registry.access.redhat.com/ubi9/ubi:
import os, subprocess, time
proc = subprocess.Popen(["sleep", "10"])
time.sleep(0.5)
print(os.readlink(f"/proc/{proc.pid}/exe"))
proc.kill()
Suggested fix
The helper only needs to know that the child has called exec(). The program name doesn't matter. Before exec(), the forked child's /proc/{pid}/exe is the parent's Python executable, so wait until it differs from the parent's:
-def _wait_for_process_exec(proc, name, timeout):
+def _wait_for_process_exec(proc, timeout):
# Wait until a child process calls exec() to replace the forked process
- # executable. Raise AssertionError on timeout.
+ # executable. Don't check the executable name: it can be a multicall
+ # binary such as /bin/busybox. Raise AssertionError on timeout.
+ parent_exe = os.readlink("/proc/self/exe")
for _ in sleeping_retry(timeout, max_delay=0.1):
exe = os.readlink(f"/proc/{proc.pid}/exe")
- if os.path.basename(exe) == name:
+ if exe != parent_exe:
break
- _wait_for_process_exec(proc, "sleep", SHORT_TIMEOUT)
+ _wait_for_process_exec(proc, SHORT_TIMEOUT)
I tested this check with the reproducer on Alpine (BusyBox) and on UBI9 with both coreutils-single and coreutils. It detects the exec() in all three cases, while the current name check fails on Alpine and on UBI9 with coreutils-single.
CPython versions tested on:
3.15.2, CPython main branch
Operating systems tested on:
Linux (Alpine 3.24 buildbots, RHEL UBI9 container)
CPython versions tested on:
3.15
Operating systems tested on:
Linux
Linked PRs
- gh-160901
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