On HP-UX with C or POSIX locale, sys.getfilesystemencoding() now returns
"ascii" instead of "roman8" (when the UTF-8 Mode is disabled and the C locale
is not coerced).
nl_langinfo(CODESET) announces "roman8" whereas it uses the Latin1
encoding in practice.
* Add Include/coreconfig.h
* Move config_*() and _PyCoreConfig_*() functions from Modules/main.c
to a new Python/coreconfig.c file.
* Inline _Py_ReadHashSeed() into config_init_hash_seed()
* Move global configuration variables to coreconfig.c
* If _Py_InitializeCore() is called twice, the second call now copies
and apply (partially) the new configuration.
* Rename _Py_CommandLineDetails to _PyCmdline
* Move more code into pymain_init(). The core configuration created
by Py_Main() is new destroyed before running Python to reduce the
memory footprint.
* _Py_InitializeCore() now returns the created interpreter.
_Py_InitializeMainInterpreter() now expects an interpreter.
* Remove _Py_InitializeEx_Private(): _freeze_importlib now uses
_Py_InitializeFromConfig()
* _PyCoreConfig_InitPathConfig() now only computes the path
configuration if needed.
* _PyCoreConfig: add isolated and site_import attributes
* Replace Py_IgnoreEnvironment with config->ignore_environment when
reading the current configuration
* _PyCoreConfig_Read() now sets ignore_environment, utf8_mode,
isolated and site_import from Py_IgnoreEnvironment, Py_UTF8Mode,
Py_IsolatedFlag and Py_NoSiteFlag
* _Py_InitializeCore() now sets Py_xxx flags from the configuration
* pymain_read_conf() now uses _PyCoreConfig_Copy() to save/restore
the configuration.
* Rename _disable_importlib of _PyCoreConfig to _install_importlib
* _PyCoreConfig_SetGlobalConfig() now also set
Py_HashRandomizationFlag
* Replace !Py_NoSiteFlag with core_config->site_import
* _PyCoreConfig_Read() no longer directly modifies Py_IsolatedFlag
and Py_NoSiteFlag global configuration flags. The function now
requires two pointers to integer, so these flags can be set later,
to avoid side effets in _PyCoreConfig_Read().
* pathconfig_global_init() now leaves Py_IsolatedFlag and
Py_NoSiteFlag unchanged.
* Fix pathconfig_global_init(): avoid computing the path
configuration twice, use _PyCoreConfig_SetPathConfig().
Rework _PyCoreConfig_Read() function which *reads* core configuration
to not *modify* the path configuration.
A new _PyCoreConfig_SetPathConfig() function now recreates the path
configuration from the core configuration. This function is now
called very late in _Py_InitializeCore(), just before calling
initimport().
Changes:
* Add _PyCoreConfig.dll_path
* Py_SetPath() now fails with a fatal python error on memory
allocation failure.
* Rename _PyPathConfig_Calculate() to _PyPathConfig_Calculate_impl()
* Replace _PyPathConfig_Init() with _PyPathConfig_Calculate(): the
function now requires a _PyPathConfig
* Add _PyPathConfig_SetGlobal() to set the _Py_path_config global
variable.
* Add _PyCoreConfig_InitPathConfig(): compute the path configuration
* Add _PyCoreConfig_SetPathConfig(): set path configuration from core
configuration
* Rename wstrlist_append() to _Py_wstrlist_append()
* _Py_wstrlist_append() now handles integer overflow.
Py_Main() can again be called after Py_Initialize(), as in Python
3.6. The new configuration is ignored, except of
_PyMainInterpreterConfig.argv which is used to update sys.argv.
External importers were being added in both phases of the import
system initialisation.
They're only supposed to be added in the second phase, after the
import machinery has been appropriately configured.
* _Py_InitializeCore() doesn't call _PyMem_SetupAllocators() anymore
if the PYTHONMALLOC environment variable is not set.
* pymain_cmdline() now sets the allocator to the default, instead of
setting the allocator in subfunctions.
* Py_SetStandardStreamEncoding() now calls
_PyMem_SetDefaultAllocator() to get a known allocator, to be able
to release the memory with the same allocator.
* Add _PyCoreConfig.install_signal_handlers
* Remove _PyMain.config: _PyMainInterpreterConfig usage is now
restricted to pymain_init_python_main().
* Rename _PyMain.core_config to _PyMain.config
* _PyMainInterpreterConfig_Read() now creates the xoptions dictionary
from the core config
* Fix _PyMainInterpreterConfig_Read(): don't replace xoptions and
argv if they are already set.
Merge _PyCoreConfig_ReadEnv() into _PyCoreConfig_Read(), and
_Py_CommandLineDetails usage is now restricted to pymain_cmdline().
Changes:
* _PyCoreConfig: Add nxoption, xoptions, nwarnoption and warnoptions
* Add _PyCoreConfig.program: argv[0] or ""
* Move filename, command, module and xoptions from
_Py_CommandLineDetails to _PyMain. xoptions _Py_OptList becomes
(int, wchar_t**) list.
* Add pymain_cmdline() function
* Rename copy_argv() to copy_wstrlist(). Rename clear_argv() to
clear_wstrlist(). Remove _Py_OptList structure: use (int,
wchar_t**) list instead.
* Rename pymain_set_flag_from_env() to pymain_get_env_flag()
* Rename pymain_set_flags_from_env() to pymain_get_env_flags()
* _PyMainInterpreterConfig_Read() now creates the warnoptions from
_PyCoreConfig.warnoptions
* Inline pymain_add_warning_dev_mode() and
pymain_add_warning_bytes_flag() into config_init_warnoptions()
* Inline pymain_get_program_name() into _PyCoreConfig_Read()
* _Py_CommandLineDetails: Replace warning_options with nwarnoption
and warnoptions. Replace env_warning_options with nenv_warnoption
and env_warnoptions.
* pymain_warnings_envvar() now has a single implementation for
Windows and Unix: use config_get_env_var_dup() to also get the
variable as wchar_t* on Unix.
* Reorganize pymain_main() to make the code more flat
* Clear configurations before pymain_update_sys_path()
* Mark Py_FatalError() and _Py_FatalInitError() with _Py_NO_RETURN
* Replace _PyMain.run_code variable with a new RUN_CODE() macro
* Move _PyMain.cf into a local variable in pymain_run_python()
Fix compiler warnings in Py_FinalizeEx(): only define variables if
they are needed, add #ifdef.
Other cleanup changes:
* _PyWarnings_InitWithConfig() is no more needed: call
_PyWarnings_Init() instead.
* Inline pymain_init_main_interpreter() in its caller. This
subfunction is no more justifed.
bpo-29240, bpo-32030: If the encoding change (C locale coerced or
UTF-8 Mode changed), Py_Main() now reads again the configuration with
the new encoding.
Changes:
* Add _Py_UnixMain() called by main().
* Rename pymain_free_pymain() to pymain_clear_pymain(), it can now be
called multipled times.
* Rename pymain_parse_cmdline_envvars() to pymain_read_conf().
* Py_Main() now clears orig_argc and orig_argv at exit.
* Remove argv_copy2, Py_Main() doesn't modify argv anymore. There is
no need anymore to get two copies of the wchar_t** argv.
* _PyCoreConfig: add coerce_c_locale and coerce_c_locale_warn.
* Py_UTF8Mode is now initialized to -1.
* Locale coercion (PEP 538) now respects -I and -E options.
Each interpreter now has its core_config and main_config copy:
* Add _PyCoreConfig_Copy() and _PyMainInterpreterConfig_Copy()
* Move _PyCoreConfig_Read(), _PyCoreConfig_Clear() and
_PyMainInterpreterConfig_Clear() from Python/pylifecycle.c to
Modules/main.c
* Fix _Py_InitializeEx_Private(): call _PyCoreConfig_ReadEnv() before
_Py_InitializeCore()
_PyMainInterpreterConfig now contains Python objects, whereas
_PyCoreConfig contains wchar_t* strings.
Core config:
* Rename _PyMainInterpreterConfig_ReadEnv() to _PyCoreConfig_ReadEnv()
* Move 3 strings from _PyMainInterpreterConfig to _PyCoreConfig:
module_search_path_env, home, program_name.
* Add _PyCoreConfig_Clear()
* _PyPathConfig_Calculate() now takes core config rather than main
config
* _PyMainInterpreterConfig_Read() now requires also a core config
Main config:
* Add _PyMainInterpreterConfig.module_search_path: sys.path list
* Add _PyMainInterpreterConfig.argv: sys.argv list
* _PyMainInterpreterConfig_Read() now computes module_search_path
* Add -X utf8 command line option, PYTHONUTF8 environment variable
and a new sys.flags.utf8_mode flag.
* If the LC_CTYPE locale is "C" at startup: enable automatically the
UTF-8 mode.
* Add _winapi.GetACP(). encodings._alias_mbcs() now calls
_winapi.GetACP() to get the ANSI code page
* locale.getpreferredencoding() now returns 'UTF-8' in the UTF-8
mode. As a side effect, open() now uses the UTF-8 encoding by
default in this mode.
* Py_DecodeLocale() and Py_EncodeLocale() now use the UTF-8 encoding
in the UTF-8 Mode.
* Update subprocess._args_from_interpreter_flags() to handle -X utf8
* Skip some tests relying on the current locale if the UTF-8 mode is
enabled.
* Add test_utf8mode.py.
* _Py_DecodeUTF8_surrogateescape() gets a new optional parameter to
return also the length (number of wide characters).
* pymain_get_global_config() and pymain_set_global_config() now
always copy flag values, rather than only copying if the new value
is greater than the old value.
* Py_Main() now starts by reading Py_xxx configuration variables to
only work on its own private structure, and then later writes back
the configuration into these variables.
* Replace Py_GETENV() with pymain_get_env_var() which ignores empty
variables.
* Add _PyCoreConfig.dump_refs
* Add _PyCoreConfig.malloc_stats
* _PyObject_DebugMallocStats() is now responsible to check if debug
hooks are installed. The function returns 1 if stats were written,
or 0 if the hooks are disabled. Mark _PyMem_PymallocEnabled() as
static.
* Simplify _PyCoreConfig_INIT, _PyMainInterpreterConfig_INIT,
_PyPathConfig_INIT macros: no need to set fields to 0/NULL, it's
redundant (the C language sets them to 0/NULL for us).
* Fix typo: pymain_run_statup() => pymain_run_startup()
* Remove a few XXX/TODO
_PyPathConfig_Init() now also initialize home and program_name:
* Rename existing _PyPathConfig_Init() to _PyPathConfig_Calculate().
Add a new _PyPathConfig_Init() function in pathconfig.c which
handles the _Py_path_config variable and call
_PyPathConfig_Calculate().
* Add home and program_name fields to _PyPathConfig.home
* _PyPathConfig_Init() now initialize home and program_name
from main_config
* Py_SetProgramName(), Py_SetPythonHome() and Py_GetPythonHome() now
calls Py_FatalError() on failure, instead of silently ignoring
failures.
* config_init_home() now gets directly _Py_path_config.home to only
get the value set by Py_SetPythonHome(), or NULL if
Py_SetPythonHome() was not called.
* config_get_program_name() now gets directly
_Py_path_config.program_name to only get the value set by
Py_SetProgramName(), or NULL if Py_SetProgramName() was not called.
* pymain_init_python() doesn't call Py_SetProgramName() anymore,
_PyPathConfig_Init() now always sets the program name
* Call _PyMainInterpreterConfig_Read() in
pymain_parse_cmdline_envvars_impl() to control the memory allocator
* C API documentation: it's no more safe to call Py_GetProgramName()
before Py_Initialize().
* Factorize code from PC/getpathp.c and Modules/getpath.c to remove
duplicated code
* rename pathconfig_clear() to _PyPathConfig_Clear()
* Inline _PyPathConfig_Fini() in pymain_impl() and then remove it,
since it's a oneliner
Changes:
* _PyPathConfig_Fini() cannot be called in Py_FinalizeEx().
Py_Initialize() and Py_Finalize() can be called multiple times, but
it must not "forget" parameters set by Py_SetProgramName(),
Py_SetPath() or Py_SetPythonHome(), whereas _PyPathConfig_Fini()
clear all these parameters.
* config_get_program_name() and calculate_program_full_path() now
also decode paths using Py_DecodeLocale() to use the
surrogateescape error handler, rather than decoding using
mbstowcs() which is strict.
* Change _Py_CheckPython3() prototype: () => (void)
* Truncate a few lines which were too long
_Py_InitializeEx_Private() now calls
_PyMainInterpreterConfig_ReadEnv() to read environment variables
PYTHONHOME and PYTHONPATH, and set the program name.
* Fix _PyMem_SetupAllocators("debug"): always restore allocators to
the defaults, rather than only caling _PyMem_SetupDebugHooks().
* Add _PyMem_SetDefaultAllocator() helper to set the "default"
allocator.
* Add _PyMem_GetAllocatorsName(): get the name of the allocators
* main() now uses debug hooks on memory allocators if Py_DEBUG is
defined, rather than calling directly malloc()
* Document default memory allocators in C API documentation
* _Py_InitializeCore() now fails with a fatal user error if
PYTHONMALLOC value is an unknown memory allocator, instead of
failing with a fatal internal error.
* Add new tests on the PYTHONMALLOC environment variable
* Add support.with_pymalloc()
* Add the _testcapi.WITH_PYMALLOC constant and expose it as
support.with_pymalloc().
* sysconfig.get_config_var('WITH_PYMALLOC') doesn't work on Windows, so
replace it with support.with_pymalloc().
* pythoninfo: add _testcapi collector for pymem
clang can't figure out that fatal_error is noreturn itself and emits warnings:
../cpython/Python/pylifecycle.c:2116:1: warning: function declared 'noreturn' should not return [-Winvalid-noreturn]
}
^
../cpython/Python/pylifecycle.c:2125:1: warning: function declared 'noreturn' should not return [-Winvalid-noreturn]
}
^
* Py_Main() now calls Py_SetProgramName() earlier to be able to get
the program name in _PyMainInterpreterConfig_ReadEnv().
* Rename prog to program_name
* Rename progpath to program_name
Py_GetPath() and Py_Main() now call
_PyMainInterpreterConfig_ReadEnv() to share the same code to get
environment variables.
Changes:
* Add _PyMainInterpreterConfig_ReadEnv()
* Add _PyMainInterpreterConfig_Clear()
* Add _PyMem_RawWcsdup()
* _PyMainInterpreterConfig: rename pythonhome to home
* Rename _Py_ReadMainInterpreterConfig() to
_PyMainInterpreterConfig_Read()
* Use _Py_INIT_USER_ERR(), instead of _Py_INIT_ERR(), for decoding
errors: the user is able to fix the issue, it's not a bug in
Python. Same change was made in _Py_INIT_NO_MEMORY().
* Remove _Py_GetPythonHomeWithConfig()
* calculate_path() rewritten in Modules/getpath.c and PC/getpathp.c
* Move global variables into a new PyPathConfig structure.
* calculate_path():
* Split the huge calculate_path() function into subfunctions.
* Add PyCalculatePath structure to pass data between subfunctions.
* Document PyCalculatePath fields.
* Move cleanup code into a new calculate_free() subfunction
* calculate_init() now handles Py_DecodeLocale() failures properly
* calculate_path() is now atomic: only replace PyPathConfig
(path_config) at once on success.
* _Py_GetPythonHomeWithConfig() now returns an error on failure
* Add _Py_INIT_NO_MEMORY() helper: report a memory allocation failure
* Coding style fixes (PEP 7)
* Py_Main() now reads the PYTHONHOME environment variable
* Add _Py_GetPythonHomeWithConfig() private function
* Add _PyWarnings_InitWithConfig()
* init_filters() doesn't get the current core configuration from the
current interpreter or Python thread anymore. Pass explicitly the
configuration to _PyWarnings_InitWithConfig().
* _Py_InitializeCore() now fails on _PyWarnings_InitWithConfig()
failure.
* Pass configuration as constant
Changes:
* Py_Main() initializes _PyCoreConfig.module_search_path_env from
the PYTHONPATH environment variable.
* PyInterpreterState_New() now initializes core_config and config
fields
* Compute sys.path a little bit ealier in
_Py_InitializeMainInterpreter() and new_interpreter()
* Add _Py_GetPathWithConfig() private function.
Py_Main() now handles two more -X options:
* -X showrefcount: new _PyCoreConfig.show_ref_count field
* -X showalloccount: new _PyCoreConfig.show_alloc_count field
Parse more env vars in Py_Main():
* Add more options to _PyCoreConfig:
* faulthandler
* tracemalloc
* importtime
* Move code to parse environment variables from _Py_InitializeCore()
to Py_Main(). This change fixes a regression from Python 3.6:
PYTHONUNBUFFERED is now read before calling pymain_init_stdio().
* _PyFaulthandler_Init() and _PyTraceMalloc_Init() now take an
argument to decide if the module has to be enabled at startup.
* tracemalloc_start() is now responsible to check the maximum number
of frames.
Other changes:
* Cleanup Py_Main():
* Rename some pymain_xxx() subfunctions
* Add pymain_run_python() subfunction
* Cleanup Py_NewInterpreter()
* _PyInterpreterState_Enable() now reports failure
* init_hash_secret() now considers pyurandom() failure as an "user
error": don't fail with abort().
* pymain_optlist_append() and pymain_strdup() now sets err on memory
allocation failure.
* Don't use "Python runtime" anymore to parse command line options or
to get environment variables: pymain_init() is now a strict
separation.
* Use an error message rather than "crashing" directly with
Py_FatalError(). Limit the number of calls to Py_FatalError(). It
prepares the code to handle errors more nicely later.
* Warnings options (-W, PYTHONWARNINGS) and "XOptions" (-X) are now
only added to the sys module once Python core is properly
initialized.
* _PyMain is now the well identified owner of some important strings
like: warnings options, XOptions, and the "program name". The
program name string is now properly freed at exit.
pymain_free() is now responsible to free the "command" string.
* Rename most methods in Modules/main.c to use a "pymain_" prefix to
avoid conflits and ease debug.
* Replace _Py_CommandLineDetails_INIT with memset(0)
* Reorder a lot of code to fix the initialization ordering. For
example, initializing standard streams now comes before parsing
PYTHONWARNINGS.
* Py_Main() now handles errors when adding warnings options and
XOptions.
* Add _PyMem_GetDefaultRawAllocator() private function.
* Cleanup _PyMem_Initialize(): remove useless global constants: move
them into _PyMem_Initialize().
* Call _PyRuntime_Initialize() as soon as possible:
_PyRuntime_Initialize() now returns an error message on failure.
* Add _PyInitError structure and following macros:
* _Py_INIT_OK()
* _Py_INIT_ERR(msg)
* _Py_INIT_USER_ERR(msg): "user" error, don't abort() in that case
* _Py_INIT_FAILED(err)
The startup refactoring means command line settings
are now applied after settings are read from the
environment.
This updates the way command line settings are applied
to account for that, ensures more settings are first read
from the environment in _PyInitializeCore, and adds a
simple test case covering the flags that are easy to check.
On Windows, Py_FatalError() now limits the size to 256 bytes of the
buffer used to call OutputDebugStringW(). Previously, the size
depended on the length of the error message.
The concrete PyDict_* API is used to interact with PyInterpreterState.modules in a number of places. This isn't compatible with all dict subclasses, nor with other Mapping implementations. This patch switches the concrete API usage to the corresponding abstract API calls.
We also add a PyImport_GetModule() function (and some other helpers) to reduce a bunch of code duplication.
A bunch of code currently uses PyInterpreterState.modules directly instead of PyImport_GetModuleDict(). This complicates efforts to make changes relative to sys.modules. This patch switches to using PyImport_GetModuleDict() uniformly. Also, a number of related uses of sys.modules are updated for uniformity for the same reason.
Note that this code was already reviewed and merged as part of #1638. I reverted that and am now splitting it up into more focused parts.
PR #1638, for bpo-28411, causes problems in some (very) edge cases. Until that gets sorted out, we're reverting the merge. PR #3506, a fix on top of #1638, is also getting reverted.
* Drop warnoptions from PyInterpreterState.
* Drop xoptions from PyInterpreterState.
* Don't set warnoptions and _xoptions again.
* Decref after adding to sys.__dict__.
* Drop an unused macro.
* Check sys.xoptions *before* we delete it.
* group the (stateful) runtime globals into various topical structs
* consolidate the topical structs under a single top-level _PyRuntimeState struct
* add a check-c-globals.py script that helps identify runtime globals
Other globals are excluded (see globals.txt and check-c-globals.py).
* group the (stateful) runtime globals into various topical structs
* consolidate the topical structs under a single top-level _PyRuntimeState struct
* add a check-c-globals.py script that helps identify runtime globals
Other globals are excluded (see globals.txt and check-c-globals.py).
- On some versions of FreeBSD, setting the "UTF-8" locale
succeeds, but a subsequent "nl_langinfo(CODESET)" fails
- adding a check for this in the coercion logic means that
coercion will happen on systems where this check succeeds,
and will be skipped otherwise
- that way CPython should automatically adapt to changes in
platform behaviour, rather than needing a new release to
enable coercion at build time
- this also allows UTF-8 to be re-enabled as a coercion
target, restoring the locale coercion behaviour on Mac OS X
- removes PY_WARN_ON_C_LOCALE build time flag
- locale coercion and compatibility warnings are now always compiled
in, but are off by default
- adds PYTHONCOERCECLOCALE=warn runtime option to aid in
debugging potentially locale related compatibility problems
Due to not-yet-resolved test failures on *BSD systems (including
Mac OS X), this also temporarily disables UTF-8 as a locale coercion
target, and skips testing the interpreter's behavior in the POSIX locale.
- new PYTHONCOERCECLOCALE config setting
- coerces legacy C locale to C.UTF-8, C.utf8 or UTF-8 by default
- always uses C.UTF-8 on Android
- uses `surrogateescape` on stdin and stdout in the coercion
target locales
- configure option to disable locale coercion at build time
- configure option to disable C locale warning at build time
* Improves test_underpth_nosite_file to reveal why it fails.
* Enable building with Windows 10 SDK.
* Fix WinSDK detection
* Fix initialization on Windows when a ._pth file exists.
* Fix tabs
* Adds comment about Py_GetPath call.
PEP 432 specifies a number of large changes to interpreter startup code, including exposing a cleaner C-API. The major changes depend on a number of smaller changes. This patch includes all those smaller changes.
is_valid_fd() now uses fstat() instead of dup() on macOS to return 0
on a pipe when the other side of the pipe is closed. fstat() fails
with EBADF in that case, whereas dup() succeed.
SHOW_ALLOC_COUNT or SHOW_TRACK_COUNT macros is now off by default. It can
be re-enabled using the "-X showalloccount" option. It now outputs to stderr
instead of stdout.
Issue #26563:
* Add _PyGILState_GetInterpreterStateUnsafe() function: the single
PyInterpreterState used by this process' GILState implementation.
* Enhance _Py_DumpTracebackThreads() to retrieve the interpreter state from
autoInterpreterState in last resort. The function now accepts NULL for interp
and current_tstate parameters.
* test_faulthandler: fix a ResourceWarning when test is interrupted by CTRL+c
Issue #10915, #15751, #26558:
* PyGILState_Check() now returns 1 (success) before the creation of the GIL and
after the destruction of the GIL. It allows to use the function early in
Python initialization and late in Python finalization.
* Add a flag to disable PyGILState_Check(). Disable PyGILState_Check() when
Py_NewInterpreter() is called
* Add assert(PyGILState_Check()) to: _Py_dup(), _Py_fstat(), _Py_read()
and _Py_write()
Issue #26558: If Py_FatalError() is called without the GIL, don't try to print
the current exception, nor try to flush stdout and stderr: only dump the
traceback of Python threads.
Issue #26516:
* Add PYTHONMALLOC environment variable to set the Python memory
allocators and/or install debug hooks.
* PyMem_SetupDebugHooks() can now also be used on Python compiled in release
mode.
* The PYTHONMALLOCSTATS environment variable can now also be used on Python
compiled in release mode. It now has no effect if set to an empty string.
* In debug mode, debug hooks are now also installed on Python memory allocators
when Python is configured without pymalloc.
CID 1291697 (#1 of 1): Dereference before null check (REVERSE_INULL)
check_after_deref: Null-checking tb suggests that it may be null, but it has already been dereferenced on all paths leading to the check.
Flushing sys.stdout and sys.stderr in Py_FatalError() can call again
Py_FatalError(). Add a reentrant flag to detect this case and just abort at the
second call.
sys.stderr
It should help to see exceptions when stderr if buffered: PyErr_Display() calls
sys.stderr.write(), it doesn't write into stderr file descriptor directly.
* Display the current Python stack if an exception was raised but the exception
has no traceback
* Disable faulthandler if an exception was raised (before it was only disabled
if no exception was raised)
* To display the current Python stack, call PyGILState_GetThisThreadState()
which works even if the GIL was released
Issue #26558: If Py_FatalError() is called without the GIL, don't try to print
the current exception, nor try to flush stdout and stderr: only dump the
traceback of Python threads.