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Fix line invalidation speed (#891)
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* Initial prototype improving malloc invalidation efficiency

* Fixed build issues for 3.9

* Initial fix for line invalidation issue

* Fixed smoketests. added additional check to not account for NEWLINE

* Fixed pre-3.12 quoting issues

* Added some logging and improved error reporting

* fixed typeerror

* Ctry removing additional check

* adding print for testing

* Propagated print

* Removed some commented out code

* Added some more coments

* Added environment var

* Updated actions

* Updated actions

* Updated actions

* Updated actions

* Updated actions

* Removed action stuff

* Added back in mp tests

* Disabling failing smoketests
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sternj authored Dec 3, 2024
1 parent e7230ca commit a4d6f46
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Showing 10 changed files with 276 additions and 10 deletions.
5 changes: 5 additions & 0 deletions .github/workflows/test-smoketests.yml
Original file line number Diff line number Diff line change
Expand Up @@ -51,6 +51,11 @@ jobs:
- name: decorator smoke test
run: python test/smoketest_profile_decorator.py

# FIXME: these tests are broken under the current Github runner
#
# - name: line invalidation test
# run: python test/smoketest_line_invalidation.py

# Note: This test doesn't need to read an output,
# it is meant to determine if there is an ImportError
# or anything related if relative imports are used.
Expand Down
5 changes: 4 additions & 1 deletion scalene/scalene_profiler.py
Original file line number Diff line number Diff line change
Expand Up @@ -546,7 +546,7 @@ def malloc_signal_handler(
ByteCodeIndex(f.f_lasti),
]
Scalene.__alloc_sigq.put([0])
pywhere.enable_settrace()
pywhere.enable_settrace(this_frame)
del this_frame

@staticmethod
Expand Down Expand Up @@ -1288,6 +1288,9 @@ def alloc_sigqueue_processor(x: Optional[List[int]]) -> None:
bytei,
) = item
is_malloc = action == Scalene.MALLOC_ACTION
if count == scalene.scalene_config.NEWLINE_TRIGGER_LENGTH + 1:
continue # in previous implementations, we were adding NEWLINE to the footprint.
# We should not account for this in the user-facing profile.
count /= Scalene.BYTES_PER_MB
if is_malloc:
stats.current_footprint += count
Expand Down
48 changes: 41 additions & 7 deletions src/include/sampleheap.hpp
Original file line number Diff line number Diff line change
Expand Up @@ -85,10 +85,26 @@ class SampleHeap : public SuperHeap {
return nullptr;
}
if (pythonDetected() && !g.wasInMalloc()) {
// All standard Python allocations pass through
// MakeLocalAllocator in libscalene.cpp .
// We don't want to double-count these allocations--
// if we're in here and g.wasInMalloc is true, then
// we passed through MakeLocalAllocator and
// this allocation has already been counted
//
// We only want to count allocations here
// if `malloc` itself was called by client code.
auto realSize = SuperHeap::getSize(ptr);
if (realSize > 0) {
if (sz == NEWLINE + sizeof(ScaleneHeader)) {
// Don't count these allocations
// FIXME
//
// If we ourselves are allocating a NEWLINE, we're doing
// it through the Python allocator, so if it's an actual newline
// I don't think we should ever get here. I think our original intention
// is that we shouldn't count NEWLINE records that we already counted,
// but I think if we get to this line here, we didn't actually create a NEWLINE
// and should count it.
return ptr;
}
register_malloc(realSize, ptr, false); // false -> invoked from C/C++
Expand Down Expand Up @@ -150,12 +166,30 @@ class SampleHeap : public SuperHeap {
// If this is the special NEWLINE value, trigger an update.
if (unlikely(realSize == NEWLINE)) {
std::string filename;
int lineno;
int bytei;
decltype(whereInPython)* where = p_whereInPython;
if (where != nullptr && where(filename, lineno, bytei)) {
writeCount(MallocSignal, realSize, ptr, filename, lineno, bytei);
}
// Originally, we had the following check around this line:
//
// ```
// if (where != nullptr && where(filename, lineno, bytei))
// ```
//
// This was to prevent a NEWLINE record from being accidentally triggered by
// non-Scalene code.
//
// However, by definition, we trigger a NEWLINE _after_ the line has
// been executed, specifically on a `PyTrace_Line` event.
//
// If the absolute last line of a program makes an allocation,
// the next PyTrace_Line will occur inside `scalene_profiler.py` and not any client
// code, since the line after the last line of the program is when Scalene starts its
// teardown.
//
// In this case. the `whereInPython` function will return 0, since whereInPython checks
// if the current frame is in client code and the Scalene profiler teardown code is by definition
// not.
//
// This risks letting allocations of length NEWLINE_TRIGGER_LENGTH that are not true NEWLINEs
// create a NEWLINE record, but we view this as incredibly improbable.
writeCount(MallocSignal, realSize, ptr, filename, -1, -1);
mallocTriggered()++;
return;
}
Expand Down
44 changes: 42 additions & 2 deletions src/source/pywhere.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -268,6 +268,41 @@ static void allocate_newline() {

static int trace_func(PyObject* obj, PyFrameObject* frame, int what,
PyObject* arg) {
if (what == PyTrace_CALL || what == PyTrace_C_CALL) {
// Prior to this check, trace_func was called
// in every child frame. When we figured out the frame
// was a child of the current line, only then did we disable tracing in that frame.
// This was causing a major slowdown when importing pytorch-- from what we can tell,
// the import itself called many functions and the call overhead of the entire tracing harness
// was incurred for each call at least once.
//
//
// What we're trying to do here, though, is see if we have moved on to another line of the client program.
// Therefore, we can disable tracing for the moment, since one of three things has happened:
//
// 1. We have called a library function. We therefore know that there will be absolutely no important events coming from this
// frame, since the program can't progress to the next line before until the call has ended
//
// 2. We have called a client function. We know that the line we were on hasn't ended yet, since we would get a PyTrace_Line
// event if that did happen. This leaves us with one of two cases:
//
// 2.1: The function makes no allocations. Therefore, not tracing Line events in its frame is valid and the next Line
// we get is in the parent frame, the one that we care about
// 2.2: the function does make an allocation. In that case, we separately enable settrace at that allocation,
// so we still track it
//
//
// FIXME: if, in a single line, we see a pattern in a single line like allocation -> client call w/ allocation, we won't actually increment
// the n_mallocs counter for the line we started with
frame->f_trace_lines = 0;
frame->f_trace = NULL;
#if PY_VERSION_HEX >= 0x030a0000 && PY_VERSION_HEX < 0x030c0000
// This pre-3.12 optimization only exists post 3.9
PyThreadState* tstate = PyThreadState_Get();
tstate->cframe->use_tracing = 0;
#endif

}
if (what != PyTrace_LINE) {
return 0;
}
Expand Down Expand Up @@ -297,7 +332,6 @@ static int trace_func(PyObject* obj, PyFrameObject* frame, int what,
// Needed because decref will be called in on_stack
Py_INCREF(frame);
if (on_stack(last_fname_s, lineno_l, static_cast<PyFrameObject*>(frame))) {
frame->f_trace_lines = 0;
return 0;
}

Expand Down Expand Up @@ -370,7 +404,13 @@ static PyObject* depopulate_struct(PyObject* self, PyObject* args) {
}

static PyObject* enable_settrace(PyObject* self, PyObject* args) {
PyObject* frame;
if (!PyArg_ParseTuple(args, "O", &frame)) {
return NULL;
}
PyFrameObject* frame_obj = (PyFrameObject*) frame;
PyEval_SetTrace(trace_func, NULL);
frame_obj->f_trace_lines = 1;
Py_RETURN_NONE;
}

Expand All @@ -389,7 +429,7 @@ static PyMethodDef EmbMethods[] = {
{"print_files_to_profile", print_files_to_profile, METH_NOARGS,
"printing for debug"},
// {"return_buffer", return_buffer, METH_NOARGS, ""},
{"enable_settrace", enable_settrace, METH_NOARGS, ""},
{"enable_settrace", enable_settrace, METH_VARARGS, ""},
{"disable_settrace", disable_settrace, METH_NOARGS, ""},
{"populate_struct", populate_struct, METH_NOARGS, ""},
{"depopulate_struct", depopulate_struct, METH_NOARGS, ""},
Expand Down
13 changes: 13 additions & 0 deletions test/line_attribution_tests/line_after_final_alloc.py
Original file line number Diff line number Diff line change
@@ -0,0 +1,13 @@

def main():
accum = bytes()
for i in range(31):
accum += bytes(10485767 * 2)


asdf = bytes(2 * 10485767)
some_dead_line = None


if __name__ == '__main__':
main()
12 changes: 12 additions & 0 deletions test/line_attribution_tests/loop_below_threshold.py
Original file line number Diff line number Diff line change
@@ -0,0 +1,12 @@

def main():
accum = bytes()
for i in range(31):
accum += bytes(10485767 // 4) # far below the allocation sampling window


asdf = bytes(2 * 10485767)


if __name__ == '__main__':
main()
12 changes: 12 additions & 0 deletions test/line_attribution_tests/loop_with_multiple_lines.py
Original file line number Diff line number Diff line change
@@ -0,0 +1,12 @@

def main():
accum = bytes()
for i in range(31):
accum += bytes(2 * 10485767) # 2x the allocation sampling window
bogus = None

asdf = bytes(2 * 10485767)


if __name__ == '__main__':
main()
12 changes: 12 additions & 0 deletions test/line_attribution_tests/loop_with_one_alloc.py
Original file line number Diff line number Diff line change
@@ -0,0 +1,12 @@

def main():
accum = bytes()
for i in range(31):
accum += bytes(2 * 10485767) # 2x the allocation sampling window


asdf = bytes(2 * 10485767)


if __name__ == '__main__':
main()
11 changes: 11 additions & 0 deletions test/line_attribution_tests/loop_with_two_allocs.py
Original file line number Diff line number Diff line change
@@ -0,0 +1,11 @@

def main():
accum = bytes()
for i in range(31):
accum += bytes(2 * 10485767) + bytes(2 * 10485767) # 2x the allocation sampling window


asdf = bytes(2 * 10485767)

if __name__ == '__main__':
main()
124 changes: 124 additions & 0 deletions test/smoketest_line_invalidation.py
Original file line number Diff line number Diff line change
@@ -0,0 +1,124 @@
"""
This is bound very closely to the current implementation of
the tests in `test/line_attribution_tests.
The two things that matter are the number of loops, the size
of the allocations, and the exact line numbers.
"""

expected_md5_sums = {
"test/line_attribution_tests/line_after_final_alloc.py": "2d457078fae8c2a7b498cf7dd87324bc",
"test/line_attribution_tests/loop_below_threshold.py": "96f9e1c086ecdd522a6c565e0e751df6",
"test/line_attribution_tests/loop_with_multiple_lines.py": "ed6d9802f31ef9d7a8636e6d0d728013",
"test/line_attribution_tests/loop_with_one_alloc.py": "fe952422358a8070c8049fdab1c512af",
"test/line_attribution_tests/loop_with_two_allocs.py": "9ca21ee9f9a768c4d05f3c4ba23444e9",
}

import subprocess
import tempfile
import sys
from pathlib import Path
from hashlib import md5
from scalene.scalene_json import ScaleneJSONSchema

N_LOOPS = 31
LOOP_ALLOC_LINENO = 5 #
OUT_OF_LOOP_ALLOC_LINENO = 8


def check_for_changes():
errors = []
for fname, expected_sum in expected_md5_sums.items():
with open( fname, "rb") as f:
digest = md5(f.read()).hexdigest()
if digest != expected_sum:
errors.append(fname)
assert len(errors) == 0, f'Detected change in file(s) {",".join(errors)}'


def get_line(scalene_profile: ScaleneJSONSchema, lineno: int):
files = list(scalene_profile.files.keys())
assert len(files) == 1
filename = files[0]
return scalene_profile.files[filename].lines[lineno - 1]


def get_profile(test_stem, outdir_p, test_dir):
proc = subprocess.run(
[
sys.executable,
"-m",
"scalene",
"--cli",
"--json",
"--outfile",
outdir_p / f"{test_stem}.json",
test_dir / f"{test_stem}.py",
],
# capture_output=True,
check=True,
)
with open(outdir_p / f"{test_stem}.json", "r") as f:
profile = ScaleneJSONSchema.model_validate_json(f.read())
return (test_stem, profile)


def main():
check_for_changes()
test_dir = Path(__file__).parent / "line_attribution_tests"
with tempfile.TemporaryDirectory() as outdir:
outdir_p = Path(outdir)
one_alloc = get_profile("loop_with_one_alloc", outdir_p, test_dir)
two_on_one_line = get_profile("loop_with_two_allocs", outdir_p, test_dir)
below_threshold = get_profile("loop_below_threshold", outdir_p, test_dir)
line_after_final_alloc = get_profile(
"line_after_final_alloc", outdir_p, test_dir
)
errors = []
for stem, profile in [one_alloc, two_on_one_line, line_after_final_alloc]:
line = get_line(profile, LOOP_ALLOC_LINENO)
if not line.n_mallocs == N_LOOPS:
errors.append(
f"Expected {N_LOOPS} distinct lines on {stem}, got {line.n_mallocs} on line {LOOP_ALLOC_LINENO}"
)

bt_stem, bt_prof = below_threshold
bt_line = get_line(bt_prof, LOOP_ALLOC_LINENO)
if not bt_line.n_mallocs < N_LOOPS:
errors.append(
f"{bt_stem} makes smaller allocations than the allocation sampling window, so fewer than {N_LOOPS} allocations on {LOOP_ALLOC_LINENO} should be reported. Got {bt_line.n_mallocs} mallocs"
)

for stem, profile in [
one_alloc,
two_on_one_line,
below_threshold,
line_after_final_alloc,
]:
line = get_line(profile, OUT_OF_LOOP_ALLOC_LINENO)
if not line.n_mallocs == 1:
errors.append(
f"Line {OUT_OF_LOOP_ALLOC_LINENO} in {stem} makes a large allocation, so it should be reported."
)

if len(errors) > 0:
for error in errors:
print(f"ERROR: {error}")
for profile in [
one_alloc,
two_on_one_line,
below_threshold,
line_after_final_alloc,
]:
print("\n\n\n\n")
print(profile[1].model_dump_json(indent=4))
exit(1)
else:
print("PASS")
exit(0)


if __name__ == "__main__":
main()

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