* error_already_set::what() is now constructed lazily
Prior to this commit throwing error_already_set was expensive due to the
eager construction of the error string (which required traversing the
Python stack). See #1853 for more context and an alternative take on the
issue.
Note that error_already_set no longer inherits from std::runtime_error
because the latter has no default constructor.
* Do not attempt to normalize if no exception occurred
This is not supported on PyPy-2.7 5.8.0.
* Extract exception name via tp_name
This is faster than dynamically looking up __name__ via GetAttrString.
Note though that the runtime of the code throwing an error_already_set
will be dominated by stack unwinding so the improvement will not be
noticeable.
Before:
396 ns ± 0.913 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)
After:
277 ns ± 0.549 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)
Benchmark:
const std::string foo() {
PyErr_SetString(PyExc_KeyError, "");
const std::string &s = py::detail::error_string();
PyErr_Clear();
return s;
}
PYBIND11_MODULE(foo, m) {
m.def("foo", &::foo);
}
* Reverted error_already_set to subclass std::runtime_error
* Revert "Extract exception name via tp_name"
The implementation of __name__ is slightly more complex than that.
It handles the module name prefix, and heap-allocated types. We could
port it to pybind11 later on but for now it seems like an overkill.
This reverts commit f1435c7e6b.
* Cosmit following @YannickJadoul's comments
Note that detail::error_string() no longer calls PyException_SetTraceback
as it is unncessary for pretty-printing the exception.
* Fixed PyPy build
* Moved normalization to error_already_set ctor
* Fix merge bugs
* Fix more merge errors
* Improve formatting
* Improve error message in rare case
* Revert back if statements
* Fix clang-tidy
* Try removing mutable
* Does build_mode release fix it
* Set to Debug to expose segfault
* Fix remove set error string
* Do not run error_string() more than once
* Trying setting the tracebackk to the value
* guard if m_type is null
* Try to debug PGI
* One last try for PGI
* Does reverting this fix PyPy
* Reviewer suggestions
* Remove unnecessary initialization
* Add noexcept move and explicit fail throw
* Optimize error_string creation
* Fix typo
* Revert noexcept
* Fix merge conflict error
* Abuse assignment operator
* Revert operator abuse
* See if we still need debug
* Remove unnecessary mutable
* Report "FATAL failure building pybind11::error_already_set error_string" and terminate process.
* Try specifying noexcept again
* Try explicit ctor
* default ctor is noexcept too
* Apply reviewer suggestions, simplify code, and make helper method private
* Remove unnecessary include
* Clang-Tidy fix
* detail::obj_class_name(), fprintf with [STDERR], [STDOUT] tags, polish comments
* consistently check m_lazy_what.empty() also in production builds
* Make a comment slightly less ambiguous.
* Bug fix: Remove `what();` from `restore()`.
It sure would need to be guarded by `if (m_type)`, otherwise `what()` fails and masks that no error was set (see update unit test). But since `error_already_set` is copyable, there is no point in releasing m_type, m_value, m_trace, therefore we can just as well avoid the runtime overhead of force-building `m_lazy_what`, it may never be used.
* Replace extremely opaque (unhelpful) error message with a truthful reflection of what we know.
* Fix clang-tidy error [performance-move-constructor-init].
* Make expected error message less specific.
* Various changes.
* bug fix: error_string(PyObject **, ...)
* Putting back the two eager PyErr_NormalizeException() calls.
* Change error_already_set() to call pybind11_fail() if the Python error indicator not set. The net result is that a std::runtime_error is thrown instead of error_already_set, but all tests pass as is.
* Remove mutable (fixes oversight in the previous commit).
* Normalize the exception only locally in error_string(). Python 3.6 & 3.7 test failures expected. This is meant for benchmarking, to determine if it is worth the trouble looking into the failures.
* clang-tidy: use auto
* Use `gil_scoped_acquire_local` in `error_already_set` destructor. See long comment.
* For Python < 3.8: `PyErr_NormalizeException` before `PyErr_WriteUnraisable`
* Go back to replacing the held Python exception with then normalized exception, if & when needed. Consistently document the side-effect.
* Slightly rewording comment. (There were also other failures.)
* Add 1-line comment for obj_class_name()
* Benchmark code, with results in this commit message.
function #calls test time [s] μs / call
master pure_unwind 729540 1.061 14.539876
err_set_unwind_err_clear 681476 1.040 15.260282
err_set_error_already_set 508038 1.049 20.640525
error_already_set_restore 555578 1.052 18.933288
pr1895_original_foo 244113 1.050 43.018168
PR / master
PR #1895 pure_unwind 736981 1.054 14.295685 98.32%
err_set_unwind_err_clear 685820 1.045 15.237399 99.85%
err_set_error_already_set 661374 1.046 15.811879 76.61%
error_already_set_restore 669881 1.048 15.645176 82.63%
pr1895_original_foo 318243 1.059 33.290806 77.39%
master @ commit ad146b2a18
Running tests in directory "/usr/local/google/home/rwgk/forked/pybind11/tests":
============================= test session starts ==============================
platform linux -- Python 3.9.10, pytest-6.2.3, py-1.10.0, pluggy-0.13.1 -- /usr/bin/python3
cachedir: .pytest_cache
rootdir: /usr/local/google/home/rwgk/forked/pybind11/tests, configfile: pytest.ini
collecting ... collected 5 items
test_perf_error_already_set.py::test_perf[pure_unwind]
PERF pure_unwind,729540,1.061,14.539876
PASSED
test_perf_error_already_set.py::test_perf[err_set_unwind_err_clear]
PERF err_set_unwind_err_clear,681476,1.040,15.260282
PASSED
test_perf_error_already_set.py::test_perf[err_set_error_already_set]
PERF err_set_error_already_set,508038,1.049,20.640525
PASSED
test_perf_error_already_set.py::test_perf[error_already_set_restore]
PERF error_already_set_restore,555578,1.052,18.933288
PASSED
test_perf_error_already_set.py::test_perf[pr1895_original_foo]
PERF pr1895_original_foo,244113,1.050,43.018168
PASSED
============================== 5 passed in 12.38s ==============================
pr1895 @ commit 8dff51d12e
Running tests in directory "/usr/local/google/home/rwgk/forked/pybind11/tests":
============================= test session starts ==============================
platform linux -- Python 3.9.10, pytest-6.2.3, py-1.10.0, pluggy-0.13.1 -- /usr/bin/python3
cachedir: .pytest_cache
rootdir: /usr/local/google/home/rwgk/forked/pybind11/tests, configfile: pytest.ini
collecting ... collected 5 items
test_perf_error_already_set.py::test_perf[pure_unwind]
PERF pure_unwind,736981,1.054,14.295685
PASSED
test_perf_error_already_set.py::test_perf[err_set_unwind_err_clear]
PERF err_set_unwind_err_clear,685820,1.045,15.237399
PASSED
test_perf_error_already_set.py::test_perf[err_set_error_already_set]
PERF err_set_error_already_set,661374,1.046,15.811879
PASSED
test_perf_error_already_set.py::test_perf[error_already_set_restore]
PERF error_already_set_restore,669881,1.048,15.645176
PASSED
test_perf_error_already_set.py::test_perf[pr1895_original_foo]
PERF pr1895_original_foo,318243,1.059,33.290806
PASSED
============================== 5 passed in 12.40s ==============================
clang++ -o pybind11/tests/test_perf_error_already_set.os -c -std=c++17 -fPIC -fvisibility=hidden -Os -flto -Wall -Wextra -Wconversion -Wcast-qual -Wdeprecated -Wnon-virtual-dtor -Wunused-result -isystem /usr/include/python3.9 -isystem /usr/include/eigen3 -DPYBIND11_STRICT_ASSERTS_CLASS_HOLDER_VS_TYPE_CASTER_MIX -DPYBIND11_TEST_BOOST -Ipybind11/include -I/usr/local/google/home/rwgk/forked/pybind11/include -I/usr/local/google/home/rwgk/clone/pybind11/include /usr/local/google/home/rwgk/forked/pybind11/tests/test_perf_error_already_set.cpp
clang++ -o lib/pybind11_tests.so -shared -fPIC -Os -flto -shared ...
Debian clang version 13.0.1-3+build2
Target: x86_64-pc-linux-gnu
Thread model: posix
* Changing call_repetitions_target_elapsed_secs to 0.1 for regular unit testing.
* Adding in `recursion_depth`
* Optimized ctor
* Fix silly bug in recurse_first_then_call()
* Add tests that have equivalent PyErr_Fetch(), PyErr_Restore() but no try-catch.
* Add call_error_string to tests. Sample only recursion_depth 0, 100.
* Show lazy-what speed-up in percent.
* Include real_work in benchmarks.
* Replace all PyErr_SetString() with generate_python_exception_with_traceback()
* Better organization of test loops.
* Add test_error_already_set_copy_move
* Fix bug in newly added test (discovered by clang-tidy): actually use move ctor
* MSVC detects the unreachable return
* change test_perf_error_already_set.py back to quick mode
* Inherit from std::exception (instead of std::runtime_error, which does not make sense anymore with the lazy what)
* Special handling under Windows.
* print with leading newline
* Removing test_perf_error_already_set (copies are under 7765113fbb).
* Avoid gil and scope overhead if there is nothing to release.
* Restore default move ctor. "member function" instead of "function" (note that "method" is Python terminology).
* Delete error_already_set copy ctor.
* Make restore() non-const again to resolve clang-tidy failure (still experimenting).
* Bring back error_already_set copy ctor, to see if that resolves the 4 MSVC test failures.
* Add noexcept to error_already_set copy & move ctors (as suggested by @skylion007 IIUC).
* Trying one-by-one noexcept copy ctor for old compilers.
* Add back test covering copy ctor. Add another simple test that exercises the copy ctor.
* Exclude more older compilers from using the noexcept = default ctors. (The tests in the previous commit exposed that those are broken.)
* Factor out & reuse gil_scoped_acquire_local as gil_scoped_acquire_simple
* Guard gil_scoped_acquire_simple by _Py_IsFinalizing() check.
* what() GIL safety
* clang-tidy & Python 3.6 fixes
* Use `gil_scoped_acquire` in dtor, copy ctor, `what()`. Remove `_Py_IsFinalizing()` checks (they are racy: https://github.com/python/cpython/pull/28525).
* Remove error_scope from copy ctor.
* Add `error_scope` to `get_internals()`, to cover the situation that `get_internals()` is called from the `error_already_set` dtor while a new Python error is in flight already. Also backing out `gil_scoped_acquire_simple` change.
* Add `FlakyException` tests with failure triggers in `__init__` and `__str__`
THIS IS STILL A WORK IN PROGRESS. This commit is only an important resting point.
This commit is a first attempt at addressing the observation that `PyErr_NormalizeException()` completely replaces the original exception if `__init__` fails. This can be very confusing even in small applications, and extremely confusing in large ones.
* Tweaks to resolve Py 3.6 and PyPy CI failures.
* Normalize Python exception immediately in error_already_set ctor.
For background see: https://github.com/pybind/pybind11/pull/1895#issuecomment-1135304081
* Fix oversights based on CI failures (copy & move ctor initialization).
* Move @pytest.mark.xfail("env.PYPY") after @pytest.mark.parametrize(...)
* Use @pytest.mark.skipif (xfail does not work for segfaults, of course).
* Remove unused obj_class_name_or() function (it was added only under this PR).
* Remove already obsolete C++ comments and code that were added only under this PR.
* Slightly better (newly added) comments.
* Factor out detail::error_fetch_and_normalize. Preparation for producing identical results from error_already_set::what() and detail::error_string(). Note that this is a very conservative refactoring. It would be much better to first move detail::error_string into detail/error_string.h
* Copy most of error_string() code to new error_fetch_and_normalize::complete_lazy_error_string()
* Remove all error_string() code from detail/type_caster_base.h. Note that this commit includes a subtle bug fix: previously error_string() restored the Python error, which will upset pybind11_fail(). This never was a problem in practice because the two PyType_Ready() calls in detail/class.h do not usually fail.
* Return const std::string& instead of const char * and move error_string() to pytypes.h
* Remove gil_scope_acquire from error_fetch_and_normalize, add back to error_already_set
* Better handling of FlakyException __str__ failure.
* Move error_fetch_and_normalize::complete_lazy_error_string() implementation from pybind11.h to pytypes.h
* Add error_fetch_and_normalize::release_py_object_references() and use from error_already_set dtor.
* Use shared_ptr for m_fetched_error => 1. non-racy, copy ctor that does not need the GIL; 2. enables guard against duplicate restore() calls.
* Add comments.
* Trivial renaming of a newly introduced member function.
* Workaround for PyPy
* Bug fix (oversight). Only valgrind got this one.
* Use shared_ptr custom deleter for m_fetched_error in error_already_set. This enables removing the dtor, copy ctor, move ctor completely.
* Further small simplification. With the GIL held, simply deleting the raw_ptr takes care of everything.
* IWYU cleanup
```
iwyu version: include-what-you-use 0.17 based on Debian clang version 13.0.1-3+build2
```
Command used:
```
iwyu -c -std=c++17 -DPYBIND11_TEST_BOOST -Iinclude/pybind11 -I/usr/include/python3.9 -I/usr/include/eigen3 include/pybind11/pytypes.cpp
```
pytypes.cpp is a temporary file: `#include "pytypes.h"`
The raw output is very long and noisy.
I decided to use `#include <cstddef>` instead of `#include <cstdio>` for `std::size_t` (iwyu sticks to the manual choice).
I ignored all iwyu suggestions that are indirectly covered by `#include <Python.h>`.
I manually verified that all added includes are actually needed.
Co-authored-by: Aaron Gokaslan <skylion.aaron@gmail.com>
Co-authored-by: Ralf W. Grosse-Kunstleve <rwgk@google.com>
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