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Commit 86d9407
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Raise where the fuzzer found aborts and stack overflows, and collect with the count in the object header (RustPython#8551)
* Correct what the non-unix frame stack is for
The comment said non-unix threading builds have no stop-the-world.
CollectStopTheWorld is gated on `feature = "threading"` alone, and
sys._current_frames stops the world on both paths; the field is the
fallback a reader uses when there is no `top_iframe` to materialize from.
Assisted-by: Claude
* Seek by the whole file position on Windows
`SetFilePointer` answers with the low half of the new position and signals
failure with INVALID_SET_FILE_POINTER, which is also that half of a
position four gigabytes in; telling them apart takes the error code, which
this did not read, so such a seek was reported as an error. Deciding
seekability from it also called such a file unseekable.
`SetFilePointerEx` returns the whole position and a success flag of its
own, which also removes the transmute of the position into halves.
Assisted-by: Claude
* memoryview: tell a value of the wrong kind from one that does not fit
Assigning an item reported every packing failure as a TypeError, so
m[0] = 300 on a 'B' view said the value was the wrong type rather than out
of range. Packing now says which of the two it was, and whether the value's
own code raised, in which case that error is the answer as it is:
m[0] = 300 ValueError: invalid value for format 'B'
m[0] = "x" TypeError: invalid type for format 'B'
m[0] = <__index__ that raises> the raised error
`struct` reports both as `struct.error` and is unchanged; the kind travels
beside the exception for the caller that tells them apart.
Also: None was read as a deletion, so m[0] = None answered "cannot delete
memory" instead of packing it; and deleting through the mapping protocol
never reached the read-only check, which comes first.
Assisted-by: Claude
* Raise MemoryError for allocations sized by Python input
os.read, _RawIOBase.read, int.to_bytes, struct.pack, ctypes array
creation and the _ssl RAND functions sized a Vec from a Python-supplied
length with vec![], which calls handle_alloc_error and, under
panic = "abort", ends the process. They now allocate through
vm.new_zeroed_bytes and raise MemoryError.
itertools.product built its pools without checking that
len(iterables) * repeat is representable; it now raises OverflowError
"repeat argument too large" and reserves the pool and index vectors
fallibly. repeat is read as isize, so a negative one raises ValueError
"repeat argument cannot be negative" instead of the conversion's message.
_ssl.RAND_bytes and RAND_pseudo_bytes read n as i32, matching the int
they are declared with.
Assisted-by: Claude
* Collect with the count in the object header
A collection kept the count it was working with in a table keyed by the
object's address, and the objects it had proved reachable in a second one.
Between them they were hashed once per candidate and twice per edge in the
heap, which is where most of a collection over a live heap went.
The count now lives in `PyInner::gc_refs`, with `GcBits::COLLECTING` saying
it is meaningful, and reachability is `gc_refs == GC_REACHABLE` rather than
membership in a set. Step 5 splits the candidates and clears the bit in one
pass. gcbench, five interleaved pairs, median: a live heap of 423k objects
goes from 0.101s to 0.055s and a dead one from 0.402s to 0.383s.
The bits, generation, owner and count take eight bytes between them. A
64-bit header had those eight as the padding its alignment forces, so it is
unchanged at 48 bytes; a 32-bit header grows from 24 to 28.
Assisted-by: Claude
* Take an explicit thread stack size as a floor in debug builds
A debug build already started Python threads on 8 MiB rather than Rust's
2 MiB default, but an explicit threading.stack_size(N) went through
verbatim. test_threading asks for 256 KiB, and starting a thread on that
walked off the end of the stack: the guard page fault landed in the
prologue of ExecutingFrame::run.
Unoptimized, that prologue reserves 80,848 bytes where the optimized one
reserves 656 -- execute_instruction is #[inline(always)] and LLVM only
colors stack slots from opt-level 1, so the frame is the sum of all 200
instruction arms' temporaries rather than the largest. A Python call costs
88,672 bytes of native stack there, and threading's bootstrap is six
frames deep, so 256 KiB holds less than half of what starting a thread
takes.
The floor reaches thread::Builder only; threading.stack_size() still
answers with what was asked for, and release builds are unchanged.
Assisted-by: Claude
* Check the native stack on every frame entry
The C-stack guard ran on one frame entry in eight. That asks the margin to
cover eight frames rather than one, and it does not: an unoptimized frame
entered through native code takes 88,672 bytes against a debug margin of
262,144. A recursion whose steps re-enter that way -- `__add__` calling
itself, a sort key that sorts -- ran off the end of the stack instead of
raising RecursionError. On a debug build `class Add: __add__ = lambda s, o:
s + o; Add() + 1` segfaulted on the main thread; it now raises, as it does
under CPython and in release builds.
enter_iframe checked and then called enter_iframe_unchecked, which checked
again; it now leaves the check to the one call.
Measured on a call-dominated benchmark, five interleaved pairs: instructions
retired go up 0.17%, about four per call, which is the stack pointer read
and the compare.
Assisted-by: Claude
* Take an iterable's length hint when a list is filled from it
`map_py_iter` read `__length_hint__` only to pass it to `PyIterIter`, and
returned an empty vector when the hint was `isize::MAX` or more. Collecting
through `PyResult` dropped the iterator's lower bound, so nothing reserved
the room the hint asked for.
`list()`, `list.extend()` and `list.__iadd__()` now reserve it and report a
hint they cannot honour as `MemoryError`; a hint that leaves no room for the
elements the list already holds is passed over, as `list_extend()` does.
`tuple()` and the other callers keep filling up without reserving.
`length_hint_opt` errors other than the `TypeError` it already turns into
`None` now reach the caller instead of being dropped.
`__iadd__` and `inplace_concat` went through `extract_cloned`, which reads
`__len__` and not `__length_hint__`; both call `PyList::extend` now, the way
`list_inplace_concat()` calls `list_extend()`.
The tuple, list and dict fast paths of `extract_elements_inner` reserve their
known length, which the `collect()` they used dropped.
Assisted-by: Claude
* Drop map.__length_hint__
`map_methods` has no `__length_hint__`, so `operator.length_hint()` on a map
answers 0, not the length of what it draws from.
The method walked into the length hint of every iterator it holds, and a
chain of maps 10000 long overflowed the native stack answering for the
outermost one. It also took the longest of its iterators, where a map stops
at the shortest.
Assisted-by: Claude
* Ask for a length hint where each caller asks for it
`map_py_iter` asked the iterable it was handed, for every caller, and reported
what asking raised. Only some callers ask it: `list_extend()` and
`_PyBytes_FromIterator()` ask the iterable, `PySequence_Tuple()` asks the
iterator, and the bytearray constructor asks nothing. `tuple()`, `min()`,
`max()`, `collections.deque()` and `f(*x)` raised for an iterable whose
`__len__` or `__length_hint__` does, where they answer.
Which object is asked is now the caller's to say. `sorted()` asks the iterable,
being `PySequence_List()`.
`bytes_from_object()` stood in for `PyBytes_FromObject()`, for
`bytearray_extend()` and for the bytearray constructor, which do not agree on
this: the first two ask, the last does not. It is split, and assigning to a
bytearray slice takes the constructor's side with `PyByteArray_FromObject()`.
`list.extend()` counted what it held before the iterable had been asked, where
`list_extend()` reads `Py_SIZE(self)` after. A `__length_hint__` that adds to
the list made the overflow guard read a count too small and raise `MemoryError`
where nothing is wrong; one that empties it made the guard skip a reservation
that cannot be served.
Assisted-by: Claude
* Settle product's pool count before it reads its arguments
`product_new()` checks `repeat` and works out `npools` before it calls
`PySequence_Tuple()` on any argument, and fills the pools `npools` times.
The pools were filled by repeating the arguments `repeat` times instead, which
walks that many steps even with no arguments to repeat: `product(repeat=2**62)`
counted up to it rather than answering `[()]`. The count was also worked out
after the arguments had been read, so a repeat too large to serve ran their
code first.
Assisted-by: Claude
* Let the bool format answer with the error its value raised
`pack_single()` leaves `'?'` to `PyObject_IsTrue()` and returns what that
raised. Packing classified the error instead, so a `ValueError` from a
`__bool__` came back as "memoryview: invalid value for format '?'".
Assisted-by: Claude
* Release a cell's old value after the lock
`PyCell::set` dropped what it replaced while still holding the mutex guarding
the cell contents. A `__del__` running from that drop and reading the same cell
waited on a lock its own caller held, so `del it` on a closure variable whose
value has such a `__del__` deadlocked.
The replaced value is now released once the guard is gone, as `Py_XSETREF`
stores before it decrefs.
Assisted-by: Claude
* Have a set iterator hold the set it iterates
The iterator kept only a reference to the inner hash table, so in
`it = iter(A(*args))` the `A()` temporary was the last owner and died as the
call returned, before `it` was bound. A `__del__` reading `it` there saw an
unbound name and its error was printed and ignored.
The iterator now holds the set object, as `si_set` does, and releases it once
exhausted. That release happens after the lock is dropped, where
`setiter_iternext()` puts its `Py_DECREF(so)` past `Py_END_CRITICAL_SECTION()`,
so a `__del__` that iterates again does not wait on a lock the call holds.
Assisted-by: Claude
* Release an exhausted iterator's container after the lock
`PositionIterInternal::_next` overwrote its `IterStatus::Active` while the
caller still held the mutex around it. Dropping the container there ran any
`__del__` under that lock, and a `__del__` that iterated the same object again
blocked on it.
`exhaust()` now hands the container back instead of dropping it, and
`locked_step()` releases it after the guard. list, list_reverseiterator, tuple,
str, dict and its views and reverse views, bytes, bytearray, memoryview,
array, deque, and the enumerate and sequence iterators all go through it.
Assisted-by: Claude
* Unskip test_free_after_iterating
Assisted-by: Claude
* Stop listing test_set as an environment polluter
`check_free_after_iterating` no longer leaves an ignored exception behind, and
the job that reruns the listed tests ten times fails once one of them stops
polluting.
Assisted-by: Claude
* Drop winsound imports left unused
`TryFromBorrowedObject`, `exceptions`, and `ToWideString` have no reference in
the module, which fails the Windows clippy line under `-Dwarnings`.
Assisted-by: Claude
* Ask nothing where the caller takes no room
`map_py_iter` asked the iterator for a length hint on behalf of every caller
that does not reserve, and reported what asking raised. Those callers ask
nothing at all: `tuple()`, `f(*x)`, `bytearray(x)`, `min()`, `max()` and
`collections.deque()` answer for an iterator whose `__length_hint__` raises,
where they had been raising it.
The answer was also never spent. It reached `PyIterIter` for a `size_hint()`
the push loop does not read, so the lookup and any call it made were work
thrown away: `tuple()` over a generator drops 22% of its instructions, and 17%
over an iterator with a `__length_hint__` written in Python.
Assisted-by: Claude
* Stop asking an iterator how long it is to walk it
`PyIter::iter` and `PyIter::into_iter` asked for a length hint and reported
what asking raised. Nothing spent the answer: it reached `PyIterIter` for a
`size_hint()` that every caller either loops past or drops, since collecting
into a `Result` reports no lower bound.
23 operations answered for an iterator whose `__length_hint__` raises, where
they had been raising it: `set`, `frozenset` and the nine `set` methods that
take an iterable, `dict.fromkeys` and the dict view operators, `array` and
`array.extend`, `all`, `any`, `sum`, `io.writelines`, `math.fsum`,
`math.prod`, and `csv.writerow` and `writerows`.
Over a generator, `set()` drops 16% of its instructions and `all()` 23%.
`str.join` and `bytes.join` do ask, reaching their elements through
`PySequence_Fast()`, which fills a list from the iterator. They take
`iter_sized()`, which is now the only way to ask. `iter_without_hint` is gone,
its callers being what `iter` already does.
Assisted-by: Claude
* Name the matrix jobs rather than let the matrix name them
A generated job name lists every value in the matrix entry, so `cargo check`
carried the booleans its dependencies and `skip_ssl` keys expand to, and the
snippets job carried its test arguments and timeout. Adding or removing a key
renames the check, which drops it from the required list until that list is
edited to match. Emptying `env_polluting_tests` renamed three checks this way.
`Run rust tests` and `clippy` keep the names they had. `cargo check` drops the
booleans from six of its nine, and the snippets job drops its arguments and
timeout from all three.
Assisted-by: Claude
* Keep a sequence iterator active when an element raises
`PositionIterInternal::_next` exhausted the iterator for any non-`Return`
result, so an error from `__getitem__` ended the walk. `iter_iternext()`
lets go of its sequence for `IndexError` and `StopIteration` alone, and
`PyIterReturn::from_getitem_result` has already turned the first of those
into the second, so only `StopIteration` exhausts now.
Both deque iterators keep exhausting on their own mutation guard, which
`deque_iternext()` does by zeroing the counter before it raises; they
share one step function for it, and the message it raises is lowercased
to match the three other sites in the module.
Assisted-by: Claude
* Name the caller in the bytes conversion TypeError
An object with no iteration protocol reached `PyObject_GetIter`'s "not
iterable" message, and `bytearray.extend()` reported bytes. Each entry
point now checks for the protocol first and names itself:
bytes(object()) cannot convert 'object' object to bytes
bytearray(object()) cannot convert 'object' object to bytearray
bytearray().extend(object()) can't extend bytearray with object
Assisted-by: Claude
* Take a strong count too large to hold as reachable
`start_gc_refs` clipped a count at `GC_REACHABLE - 1`, a number the
per-reference subtraction could still walk down to zero and collect a
live object. It now stores `GC_REACHABLE`, and `subtract_gc_ref` leaves
that value alone.
Assisted-by: Claude
* Raise AssertionError where a snippet asserts False
`assert False` is removed under `-O`, which the snippet suite may run.
Assisted-by: Claude
* Keep raising for a collection that moved under its iterator
A deque, set or dict iterator raised once and then read as spent. The
guard is sticky: `deque_iternext()` looks at the deque's state before the
count it keeps, and `dictiter_iternextkey()` and `setiter_iternext()`
write a size no collection can have, so every later call finds the same
thing and raises again. `dequereviter_next()` is the one exception,
looking at its count first, so it runs out after the first raise.
Both deque iterators now carry `dequeiterobject.counter` rather than
reading a length back from the deque, and the dict and set iterators
compare the size they captured against the collection's own every time
they are asked how much is left, which is what makes that answer nothing
from the moment the collection changes rather than only once the
iterator has raised.
The set's message is capitalized to match `setiter_iternext()`.
Measured against 3.14.6, for each of deque, reversed deque, set, dict
and a reversed dict view: the hint after the change, the error, the hint
after the error, and what a later call answers.
Assisted-by: Claude
* Give apt-get update a deadline to fail on
The step waits on `apt-get update`, which has no deadline of its own, so
a source that takes the connection and then stops answering holds the
job until the workflow's own timeout. The retry that disables the
Microsoft and azure-cli sources runs only when the update exits
non-zero, which a held connection never does; three jobs on this branch
sat on this step for 20 minutes to five and a half hours.
Each attempt is now bounded, and the transports are given a timeout, so
a source that stops answering reaches the retry.
Assisted-by: Claude1 parent ca907d1 commit 86d9407
56 files changed
Lines changed: 1548 additions & 415 deletions
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