Isolate the faulthandler Module Between Interpreters
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Description
(See gh-100227.)
Currently the faulthandler module has some state in _PyRuntimeState, including objects, which is shared by all interpreters. Interpreters should be isolated from each other, for a variety of reasons (including the possibility of a per-interpreter GIL). Isolating the module will involve moving some of the state to PyInterpreterState (and, under per-interpreter GIL, guarding other state with a global lock).
Code Analysis:
(expand)
Signals
The module installs handlers for various signals.
(expand)
fatal:
SIGBUS- bus errorSIGILL- illegal instructionSIGFPE- floating point exceptionSIGABRT- abortSIGSEGV- segfault
"user":
- the 5 fatal signals
- others (up to
Py_NSIG)
handlers:
faulthandler_fatal_error(signum)faulthandler_exc_handler()(on Windows)faulthandler_user()
State
Fields
https://github.com/python/cpython/blob/main/Include/internal/pycore_faulthandler.h#L49-L86
https://github.com/python/cpython/blob/main/Include/internal/pycore_runtime.h#L146
raw
https://github.com/python/cpython/blob/62251c3da06eb4662502295697f39730565b1717/Include/internal/pycore_faulthandler.h#L49-L86
https://github.com/python/cpython/blob/62251c3da06eb4662502295697f39730565b1717/Include/internal/pycore_faulthandler.h#L36-L46
tables:
name |
type |
#ifdef |
notes |
|---|---|---|---|
fatal_error |
|||
. enabled |
bool |
"is faulthandler enabled?" | |
. file |
PyObject * |
only for keeping .fd alive |
|
. fd |
int |
||
. all_threads |
bool |
||
. interp |
PyInterpreterState * |
show only its threads the one that enabled faulthandler |
|
. exc_handler |
void * |
MS_WINDOWS |
|
name |
type |
#ifdef |
notes |
thread |
--- | ||
. file |
PyObject * |
only for keeping .fd alive |
|
. fd |
int |
defaults to sys.stderr |
|
. timeout_us |
PY_TIMEOUT_T |
||
. repeat |
bool |
||
. interp |
PyInterpreterState * |
show only its threads the one that requested the info |
|
. exit |
bool |
||
. header |
char * |
||
. header_len |
size_t |
||
. cancel_event |
PyThread_type_lock |
||
. running |
PyThread_type_lock |
||
name |
type |
#ifdef |
notes |
user_signals |
struct faulthandler_user_signal * |
FAULTHANDLER_USER |
a dynamically allocated array (Py_NSIG) |
user_signals[signum] |
--- | ||
. enabled |
bool |
||
. file |
PyObject * |
||
. fd |
int |
||
. all_threads |
bool |
||
. chain |
bool |
||
. previous |
_Py_sighandler_t |
||
. interp |
PyInterpreterState * |
show only its threads the one that added the handler |
|
name |
type |
#ifdef |
notes |
old_stack |
stack_t |
FAULTHANDLER_USE_ALT_STACK |
|
stack |
stack_t |
FAULTHANDLER_USE_ALT_STACK |
Usage
simple:
name |
context |
get |
set |
|---|---|---|---|
fatal_error |
|||
. enabled |
module | faulthandler_is_enabled() |
faulthandler_disable_py() |
| signal | faulthandler_fatal_error() |
||
| internal | faulthandler_enable()faulthandler_disable() |
faulthandler_enable()faulthandler_disable() |
|
. file |
module | faulthandler_traverse() |
faulthandler_py_enable()faulthandler_traverse() |
| internal | faulthandler_disable() |
faulthandler_disable() |
|
. fd |
module | ||
| signal | faulthandler_fatal_error()faulthandler_exc_handler() |
||
. all_threads |
module | faulthandler_py_enable() |
|
| signal | faulthandler_fatal_error()faulthandler_exc_handler() |
||
. interp |
module | faulthandler_py_enable() |
|
| internal | faulthandler_fatal_error()faulthandler_exc_handler() |
||
. exc_handler |
internal | faulthandler_enable()faulthandler_disable() |
faulthandler_enable()faulthandler_disable() |
name |
context |
get |
set |
thread |
|||
. file |
module | faulthandler_dump_traceback_later()faulthandler_traverse() |
faulthandler_dump_traceback_later()faulthandler_traverse() |
| internal | cancel_dump_traceback_later() |
cancel_dump_traceback_later() |
|
. fd |
|||
| module | faulthandler_dump_traceback_later() |
||
| thread | faulthandler_thread() |
||
. timeout_us |
module | faulthandler_dump_traceback_later() |
|
| thread | faulthandler_thread() |
||
. repeat |
module | faulthandler_dump_traceback_later() |
|
| thread | faulthandler_thread() |
||
. interp |
module | faulthandler_dump_traceback_later() |
|
| thread | faulthandler_thread() |
||
. exit |
module | faulthandler_dump_traceback_later() |
|
| thread | faulthandler_thread() |
||
. header |
module | faulthandler_dump_traceback_later() |
|
| thread | faulthandler_thread() |
||
| internal | cancel_dump_traceback_later() |
cancel_dump_traceback_later() |
|
. header_len |
module | faulthandler_dump_traceback_later() |
|
| thread | faulthandler_thread() |
||
. cancel_event |
module | faulthandler_dump_traceback_later() |
faulthandler_dump_traceback_later() |
| thread | faulthandler_thread() |
||
| internal | cancel_dump_traceback_later() |
||
. running |
module | faulthandler_dump_traceback_later() |
faulthandler_dump_traceback_later() |
| thread | faulthandler_thread() |
||
| internal | cancel_dump_traceback_later() |
||
name |
context |
get |
set |
user_signals |
module | faulthandler_register_py()faulthandler_unregister_py() |
faulthandler_register_py()faulthandler_traverse() |
| C-API | _PyFaulthandler_Fini() |
_PyFaulthandler_Fini() |
|
| signal | faulthandler_user() |
||
user_signals[signum] |
|||
. enabled |
module | faulthandler_register_py() |
faulthandler_register_py() |
| signal | faulthandler_user() |
||
| internal | faulthandler_unregister() |
faulthandler_unregister() |
|
. file |
module | faulthandler_register_py()faulthandler_traverse() |
faulthandler_register_py()faulthandler_traverse() |
| internal | faulthandler_unregister() |
faulthandler_unregister() |
|
. fd |
module | faulthandler_register_py() |
|
| signal | faulthandler_user() |
||
| internal | faulthandler_unregister() |
||
. all_threads |
module | faulthandler_register_py() |
|
| signal | faulthandler_user() |
||
. chain |
module | faulthandler_register_py() |
|
| signal | faulthandler_user() |
||
. previous |
module | faulthandler_register_py() |
|
| signal | faulthandler_user() |
||
| internal | faulthandler_unregister() |
||
. interp |
module | faulthandler_register_py() |
|
| signal | faulthandler_user() |
||
name |
context |
get |
set |
stack |
C-API | _PyFaulthandler_Init()_PyFaulthandler_Fini() |
|
| internal | faulthandler_enable()faulthandler_register()faulthandler_allocate_stack() |
||
old_stack |
C-API | _PyFaulthandler_Fini() |
modify data in complex fields:
name |
context |
calls |
|---|---|---|
fatal_error .fd |
signal | faulthandler_fatal_error() -> faulthandler_dump_traceback()faulthandler_fatal_error() -> _Py_DumpExtensionModules()faulthandler_exc_handler()faulthandler_exc_handler() -> _Py_DumpHexadecimal()faulthandler_exc_handler() -> faulthandler_dump_traceback() |
thread.fd |
thread | faulthandler_thread() -> _Py_write_noraise()faulthandler_thread() -> _Py_DumpTracebackThreads() |
thread .cancel_event |
module | faulthandler_dump_traceback_later() |
| C-API | _PyFaulthandler_Fini() |
|
| thread | faulthandler_thread() |
|
| internal | cancel_dump_traceback_later() |
|
thread .running |
module | faulthandler_dump_traceback_later() |
| thread | faulthandler_thread() |
|
| internal | cancel_dump_traceback_later() |
|
user_signals[signum] .fd |
signal | faulthandler_user() -> faulthandler_dump_traceback() |
stack |
C-API | _PyFaulthandler_Init()_PyFaulthandler_Fini() |
| internal | faulthandler_allocate_stack() |
|
old_stack |
internal | faulthandler_allocate_stack() -> sigaltstack() |
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with Include/internal/pycore_faulthandler.h and Include/internal/pycore_runtime.h, then trace the listed entry points such as _PyFaulthandler_Init(), _PyFaulthandler_Fini(), faulthandler_enable(), and faulthandler_user(). Map each shared field from the state tables to its interpreter or global ownership, and verify that faulthandler state is isolated without breaking signal-handler behavior.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- c, python
- Domain
- operating-systems
- Issue type
- Refactor
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 25/100