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Merged
vstinner merged 4 commits into from
Aug 7, 2026
Merged

gh-98894: Fix dtrace tests in shared builds #153372

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90f8699
gh-98894: Fix dtrace tests in shared builds
stratakis Jul 8, 2026
9d87605
Truncate external tracer error output
stratakis Jul 8, 2026
bf2da78
Revert "Truncate external tracer error output"
stratakis Aug 7, 2026
b07f88b
Address review
stratakis Aug 7, 2026
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7 changes: 4 additions & 3 deletions Lib/test/dtracedata/call_stack.stp
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Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,7 @@ function basename:string(path:string)
return last_token;
}

probe process.mark("function__entry")
probe @PYTHON_SYSTEMTAP_PROBE@("function__entry")
{
funcname = user_string($arg2);

Expand All @@ -19,7 +19,8 @@ probe process.mark("function__entry")
}
}

probe process.mark("function__entry"), process.mark("function__return")
probe @PYTHON_SYSTEMTAP_PROBE@("function__entry"),
@PYTHON_SYSTEMTAP_PROBE@("function__return")
{
filename = user_string($arg1);
funcname = user_string($arg2);
Expand All @@ -31,7 +32,7 @@ probe process.mark("function__entry"), process.mark("function__return")
}
}

probe process.mark("function__return")
probe @PYTHON_SYSTEMTAP_PROBE@("function__return")
{
funcname = user_string($arg2);

Expand Down
7 changes: 4 additions & 3 deletions Lib/test/dtracedata/gc.stp
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
global tracing

probe process.mark("function__entry")
probe @PYTHON_SYSTEMTAP_PROBE@("function__entry")
{
funcname = user_string($arg2);

Expand All @@ -9,14 +9,15 @@ probe process.mark("function__entry")
}
}

probe process.mark("gc__start"), process.mark("gc__done")
probe @PYTHON_SYSTEMTAP_PROBE@("gc__start"),
@PYTHON_SYSTEMTAP_PROBE@("gc__done")
{
if (tracing) {
printf("%d\t%s:%ld\n", gettimeofday_us(), $$name, $arg1);
}
}

probe process.mark("function__return")
probe @PYTHON_SYSTEMTAP_PROBE@("function__return")
{
funcname = user_string($arg2);

Expand Down
121 changes: 91 additions & 30 deletions Lib/test/test_dtrace.py
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@
import subprocess
import sys
import sysconfig
import tempfile
import types
import unittest

Expand All @@ -25,6 +26,42 @@ def abspath(filename):
return os.path.abspath(findfile(filename, subdir="dtracedata"))


def get_probe_binary():
binary = sys.executable
if sysconfig.get_config_var("Py_ENABLE_SHARED"):
lib_dir = sysconfig.get_config_var("LIBDIR")
if not lib_dir or sysconfig.is_python_build():
lib_dir = os.path.abspath(os.path.dirname(sys.executable))

lib_names = []
for name in (
sysconfig.get_config_var("INSTSONAME"),
sysconfig.get_config_var("LDLIBRARY"),
):
if name and name not in lib_names:
lib_names.append(name)

if lib_dir:
for name in lib_names:
libpython_path = os.path.join(lib_dir, name)
if os.path.exists(libpython_path):
binary = libpython_path
break

return binary


def truncate_output(output, *, max_lines=3, max_chars=500):
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lines = [line.strip() for line in output.splitlines() if line.strip()]
omitted = len(lines) - max_lines
output = "; ".join(lines[:max_lines])
if omitted > 0:
output += f"; ... ({omitted} lines omitted)"
if len(output) > max_chars:
output = output[:max_chars - 3] + "..."
return output


def normalize_trace_output(output):
"""Normalize DTrace output for comparison.

Expand Down Expand Up @@ -95,7 +132,8 @@ def run_readelf(cmd):
raise AssertionError(
f"Command {shlex.join(cmd)!r} failed "
f"with exit code {proc.returncode}: "
f"stdout={stdout!r} stderr={stderr!r}"
f"stdout={truncate_output(stdout)!r} "
f"stderr={truncate_output(stderr)!r}"
)

return stdout
Expand Down Expand Up @@ -141,7 +179,8 @@ def trace(self, script_file, subcommand=None, *, timeout=None,
if check_returncode and proc.returncode:
raise AssertionError(
f"Command {shlex.join(command)!r} failed "
f"with exit code {proc.returncode}: output={stdout!r}"
f"with exit code {proc.returncode}: "
f"output={truncate_output(stdout)!r}"
)
return stdout

Expand All @@ -166,7 +205,9 @@ def assert_usable(self):
output = str(fnfe)
if output != "probe: success":
raise unittest.SkipTest(
"{}(1) failed: {}".format(self.COMMAND[0], output)
"{}(1) failed: {}".format(
self.COMMAND[0], truncate_output(output)
)
)


Expand All @@ -180,6 +221,43 @@ class DTraceBackend(TraceBackend):
class SystemTapBackend(TraceBackend):
EXTENSION = ".stp"
COMMAND = ["stap", "-g"]
PROBE_PLACEHOLDER = "@PYTHON_SYSTEMTAP_PROBE@"

@staticmethod
def _quote_systemtap_string(value):
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return value.replace("\\", "\\\\").replace('"', '\\"')

def _python_probe(self):
executable = self._quote_systemtap_string(sys.executable)
probe_binary = get_probe_binary()
if probe_binary != sys.executable:
probe_binary = self._quote_systemtap_string(probe_binary)
return f'process("{executable}").library("{probe_binary}").mark'
return f'process("{executable}").mark'
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def _render_script(self, script_file):
with open(script_file) as script:
return script.read().replace(
self.PROBE_PLACEHOLDER, self._python_probe()
)
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def trace(self, script_file, subcommand=None, *, timeout=None,
check_returncode=False):
with tempfile.NamedTemporaryFile(
mode="w", encoding="utf-8", suffix=self.EXTENSION, delete=False
) as script:
script.write(self._render_script(script_file))
generated_script_file = script.name

try:
return super().trace(
generated_script_file,
subcommand,
timeout=timeout,
check_returncode=check_returncode,
)
finally:
os.unlink(generated_script_file)
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class BPFTraceBackend(TraceBackend):
Expand Down Expand Up @@ -273,7 +351,7 @@ def run_case(self, name, optimize_python=None):
python_flags.extend(["-O"] * optimize_python)

subcommand = [sys.executable] + python_flags + [python_file]
program = self.PROGRAMS[name].format(python=sys.executable)
program = self.PROGRAMS[name].format(python=get_probe_binary())

try:
proc = create_process_group(
Expand All @@ -291,7 +369,8 @@ def run_case(self, name, optimize_python=None):

if proc.returncode != 0:
raise AssertionError(
f"bpftrace failed with code {proc.returncode}:\n{stderr}"
f"bpftrace failed with code {proc.returncode}: "
f"{truncate_output(stderr)}"
)

stdout = self._filter_probe_rows(stdout)
Expand All @@ -312,7 +391,7 @@ def run_case(self, name, optimize_python=None):

def assert_usable(self):
# Check if bpftrace is available and can attach to USDT probes
program = f'usdt:{sys.executable}:python:function__entry {{ printf("probe: success\\n"); exit(); }}'
program = f'usdt:{get_probe_binary()}:python:function__entry {{ printf("probe: success\\n"); exit(); }}'
try:
proc = create_process_group(
["bpftrace", "-e", program, "-c",
Expand All @@ -331,12 +410,15 @@ def assert_usable(self):
# Check for permission errors (bpftrace usually requires root)
if proc.returncode != 0:
raise unittest.SkipTest(
f"bpftrace(1) failed with code {proc.returncode}: {stderr}"
f"bpftrace(1) failed with code {proc.returncode}: "
f"{truncate_output(stderr)}"
)

if "probe: success" not in stdout:
raise unittest.SkipTest(
f"bpftrace(1) failed: stdout={stdout!r} stderr={stderr!r}"
f"bpftrace(1) failed: "
f"stdout={truncate_output(stdout)!r} "
f"stderr={truncate_output(stderr)!r}"
)


Expand Down Expand Up @@ -455,28 +537,7 @@ def get_readelf_version():
return int(match.group(1)), int(match.group(2))

def get_readelf_output(self):
binary = sys.executable
if sysconfig.get_config_var("Py_ENABLE_SHARED"):
lib_dir = sysconfig.get_config_var("LIBDIR")
if not lib_dir or sysconfig.is_python_build():
lib_dir = os.path.abspath(os.path.dirname(sys.executable))

lib_names = []
for name in (
sysconfig.get_config_var("INSTSONAME"),
sysconfig.get_config_var("LDLIBRARY"),
):
if name and name not in lib_names:
lib_names.append(name)

if lib_dir:
for name in lib_names:
libpython_path = os.path.join(lib_dir, name)
if os.path.exists(libpython_path):
binary = libpython_path
break

return run_readelf(["readelf", "-n", binary])
return run_readelf(["readelf", "-n", get_probe_binary()])

def test_check_probes(self):
readelf_output = self.get_readelf_output()
Expand Down
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