faulthandler
bdb — 调试器框架
bdb
Added in version 3.3.
This module contains functions to dump Python tracebacks explicitly, on a fault, after a timeout, or on a user signal. Call faulthandler.enable() to install fault handlers for the SIGSEGV , SIGFPE , SIGABRT , SIGBUS ，和 SIGILL signals. You can also enable them at startup by setting the PYTHONFAULTHANDLER environment variable or by using the -X faulthandler 命令行选项。
faulthandler.enable()
SIGSEGV
SIGFPE
SIGABRT
SIGBUS
SIGILL
PYTHONFAULTHANDLER
-X
The fault handler is compatible with system fault handlers like Apport or the Windows fault handler. The module uses an alternative stack for signal handlers if the sigaltstack() function is available. This allows it to dump the traceback even on a stack overflow.
sigaltstack()
The fault handler is called on catastrophic cases and therefore can only use signal-safe functions (e.g. it cannot allocate memory on the heap). Because of this limitation traceback dumping is minimal compared to normal Python tracebacks:
仅支持 ASCII。 backslashreplace error handler is used on encoding.
backslashreplace
Each string is limited to 500 characters.
Only the filename, the function name and the line number are displayed. (no source code)
It is limited to 100 frames and 100 threads.
The order is reversed: the most recent call is shown first.
By default, the Python traceback is written to sys.stderr . To see tracebacks, applications must be run in the terminal. A log file can alternatively be passed to faulthandler.enable() .
sys.stderr
The module is implemented in C, so tracebacks can be dumped on a crash or when Python is deadlocked.
The Python 开发模式 调用 faulthandler.enable() 在 Python 启动时。
另请参阅
pdb
Interactive source code debugger for Python programs.
traceback
Standard interface to extract, format and print stack traces of Python programs.
Dump the tracebacks of all threads into file 。若 all_threads is False , dump only the current thread.
False
traceback.print_tb() , which can be used to print a traceback object.
traceback.print_tb()
3.5 版改变： Added support for passing file descriptor to this function.
Enable the fault handler: install handlers for the SIGSEGV , SIGFPE , SIGABRT , SIGBUS and SIGILL signals to dump the Python traceback. If all_threads is True , produce tracebacks for every running thread. Otherwise, dump only the current thread.
True
The file must be kept open until the fault handler is disabled: see issue with file descriptors .
3.6 版改变： On Windows, a handler for Windows exception is also installed.
3.10 版改变： The dump now mentions if a garbage collector collection is running if all_threads 为 True。
Disable the fault handler: uninstall the signal handlers installed by enable() .
enable()
Check if the fault handler is enabled.
Dump the tracebacks of all threads, after a timeout of timeout seconds, or every timeout seconds if repeat is True 。若 exit is True ，调用 _exit() with status=1 after dumping the tracebacks. (Note _exit() exits the process immediately, which means it doesn’t do any cleanup like flushing file buffers.) If the function is called twice, the new call replaces previous parameters and resets the timeout. The timer has a sub-second resolution.
_exit()
The file must be kept open until the traceback is dumped or cancel_dump_traceback_later() is called: see issue with file descriptors .
cancel_dump_traceback_later()
This function is implemented using a watchdog thread.
3.7 版改变： This function is now always available.
Cancel the last call to dump_traceback_later() .
dump_traceback_later()
Register a user signal: install a handler for the signum signal to dump the traceback of all threads, or of the current thread if all_threads is False ，进 file . Call the previous handler if chain is True .
The file must be kept open until the signal is unregistered by unregister() : see issue with file descriptors .
unregister()
不可用于 Windows。
Unregister a user signal: uninstall the handler of the signum signal installed by register() 。返回 True if the signal was registered, False 否则。
register()
enable() , dump_traceback_later() and register() keep the file descriptor of their file argument. If the file is closed and its file descriptor is reused by a new file, or if os.dup2() is used to replace the file descriptor, the traceback will be written into a different file. Call these functions again each time that the file is replaced.
os.dup2()
Example of a segmentation fault on Linux with and without enabling the fault handler:
$ python -c "import ctypes; ctypes.string_at(0)" Segmentation fault $ python -q -X faulthandler >>> import ctypes >>> ctypes.string_at(0) Fatal Python error: Segmentation fault Current thread 0x00007fb899f39700 (most recent call first): File "/home/python/cpython/Lib/ctypes/__init__.py", line 486 in string_at File "<stdin>", line 1 in <module> Segmentation fault
pdb — Python 调试器
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