The setobject freelist was consuming memory but not providing much value.
Even when a freelisted setobject was available, most of the setobject
fields still needed to be initialized and the small table still required
a memset(). This meant that the custom freelisting scheme for sets was
providing almost no incremental benefit over the default Python freelist
scheme used by _PyObject_Malloc() in Objects/obmalloc.c.
-I
Run Python in isolated mode. This also implies -E and -s. In isolated mode
sys.path contains neither the script’s directory nor the user’s
site-packages directory. All PYTHON* environment variables are ignored,
too. Further restrictions may be imposed to prevent the user from
injecting malicious code.
PyStructSequence_InitType() except that it has a return value (0 on success,
-1 on error).
* PyStructSequence_InitType2() now raises MemoryError on memory allocation failure
* Fix also some calls to PyDict_SetItemString(): handle error
Add new enum:
* PyMemAllocatorDomain
Add new structures:
* PyMemAllocator
* PyObjectArenaAllocator
Add new functions:
* PyMem_RawMalloc(), PyMem_RawRealloc(), PyMem_RawFree()
* PyMem_GetAllocator(), PyMem_SetAllocator()
* PyObject_GetArenaAllocator(), PyObject_SetArenaAllocator()
* PyMem_SetupDebugHooks()
Changes:
* PyMem_Malloc()/PyObject_Realloc() now always call malloc()/realloc(), instead
of calling PyObject_Malloc()/PyObject_Realloc() in debug mode.
* PyObject_Malloc()/PyObject_Realloc() now falls back to
PyMem_Malloc()/PyMem_Realloc() for allocations larger than 512 bytes.
* Redesign debug checks on memory block allocators as hooks, instead of using C
macros
* Add a new PyMemAllocators structure
* New functions:
- PyMem_RawMalloc(), PyMem_RawRealloc(), PyMem_RawFree(): GIL-free memory
allocator functions
- PyMem_GetRawAllocators(), PyMem_SetRawAllocators()
- PyMem_GetAllocators(), PyMem_SetAllocators()
- PyMem_SetupDebugHooks()
- _PyObject_GetArenaAllocators(), _PyObject_SetArenaAllocators()
* Add unit test for PyMem_Malloc(0) and PyObject_Malloc(0)
* Add unit test for new get/set allocators functions
* PyObject_Malloc() now falls back on PyMem_Malloc() instead of malloc() if
size is bigger than SMALL_REQUEST_THRESHOLD, and PyObject_Realloc() falls
back on PyMem_Realloc() instead of realloc()
* PyMem_Malloc() and PyMem_Realloc() now always call malloc() and realloc(),
instead of calling PyObject_Malloc() and PyObject_Realloc() in debug mode
Forgot to raise ModuleNotFoundError when None is found in sys.modules.
This led to introducing the C function PyErr_SetImportErrorSubclass()
to make setting ModuleNotFoundError easier.
Also updated the reference docs to mention ModuleNotFoundError
appropriately. Updated the docs for ModuleNotFoundError to mention the
None in sys.modules case.
Lastly, it was noticed that PyErr_SetImportError() was not setting an
exception when returning None in one case. That issue is now fixed.
ImportError.
The exception is raised by import when a module could not be found.
Technically this is defined as no viable loader could be found for the
specified module. This includes ``from ... import`` statements so that
the module usage is consistent for all situations where import
couldn't find what was requested.
This should allow for the common idiom of::
try:
import something
except ImportError:
pass
to be updated to using ModuleNotFoundError and not accidentally mask
ImportError messages that should propagate (e.g. issues with a
loader).
This work was driven by the fact that the ``from ... import``
statement needed to be able to tell the difference between an
ImportError that simply couldn't find a module (and thus silence the
exception so that ceval can raise it) and an ImportError that
represented an actual problem.
Note that this is a potentially disruptive change since it may
release some system resources which would otherwise remain
perpetually alive (e.g. database connections kept in thread-local
storage).
* Add also min_char attribute to _PyUnicodeWriter structure (currently unused)
* _PyUnicodeWriter_Init() has no more argument (except the writer itself):
min_length and overallocate must be set explicitly
* In error handlers, only enable overallocation if the replacement string
is longer than 1 character
* CJK decoders don't use overallocation anymore
* Set min_length, instead of preallocating memory using
_PyUnicodeWriter_Prepare(), in many decoders
* _PyUnicode_DecodeUnicodeInternal() checks for integer overflow
Write a function to enable more optimizations:
* If the substring is the whole string and overallocation is disabled, just
keep a reference to the string, don't copy characters
* Avoid a call to the expensive _PyUnicode_FindMaxChar() function when
possible
computation as the overflow behavior of signed integers is undefined.
NOTE: This change is smaller compared to 3.2 as much of this cleanup had
already been done. I added the comment that my change in 3.2 added so that the
code would match up. Otherwise this just adds or synchronizes appropriate UL
designations on some constants to be pedantic.
In practice we require compiling everything with -fwrapv which forces overflow
to be defined as twos compliment but this keeps the code cleaner for checkers
or in the case where someone has compiled it without -fwrapv or their
compiler's equivalent. We could work to get rid of the -fwrapv requirement
in 3.4 but that requires more planning.
Found by Clang trunk's Undefined Behavior Sanitizer (UBSan).
Cleanup only - no functionality or hash values change.
computation as the overflow behavior of signed integers is undefined.
NOTE: This change is smaller compared to 3.2 as much of this cleanup had
already been done. I added the comment that my change in 3.2 added so that the
code would match up. Otherwise this just adds or synchronizes appropriate UL
designations on some constants to be pedantic.
In practice we require compiling everything with -fwrapv which forces overflow
to be defined as twos compliment but this keeps the code cleaner for checkers
or in the case where someone has compiled it without -fwrapv or their
compiler's equivalent.
Found by Clang trunk's Undefined Behavior Sanitizer (UBSan).
Cleanup only - no functionality or hash values change.
computation as the overflow behavior of signed integers is undefined.
In practice we require compiling everything with -fwrapv which forces overflow
to be defined as twos compliment but this keeps the code cleaner for checkers
or in the case where someone has compiled it without -fwrapv or their
compiler's equivalent.
Found by Clang trunk's Undefined Behavior Sanitizer (UBSan).
Cleanup only - no functionality or hash values change.
longer required as of Python 2.5+ when the gc_refs changed from an int (4
bytes) to a Py_ssize_t (8 bytes) as the minimum size is 16 bytes.
The use of a 'long double' triggered a warning by Clang trunk's
Undefined-Behavior Sanitizer as on many platforms a long double requires
16-byte alignment but the Python memory allocator only guarantees 8 byte
alignment.
So our code would allocate and use these structures with technically improper
alignment. Though it didn't matter since the 'dummy' field is never used.
This silences that warning.
Spelunking into code history, the double was added in 2001 to force better
alignment on some platforms and changed to a long double in 2002 to appease
Tru64. That issue should no loner be present since the upgrade from int to
Py_ssize_t where the minimum structure size increased to 16 (unless anyone
knows of a platform where ssize_t is 4 bytes?) or 24 bytes depending on if the
build uses 4 or 8 byte pointers.
We can probably get rid of the double and this union hack all together today.
That is a slightly more invasive change that can be left for later.
A more correct non-hacky alternative if any alignment issues are still found
would be to use a compiler specific alignment declaration on the structure and
determine which value to use at configure time.
Larry Hastings
Raymond Hettinger
Antoine Pitrou
Victor Stinner
Serhiy Storchaka
Ezio Melotti
Christian Heimes
Brett Cannon
Richard Oudkerk
Eli Bendersky
Benjamin Peterson
Georg Brandl
Charles-Francois Natali
Alexandre Vassalotti
Kristján Valur Jónsson
Terry Jan Reedy
Andrew Svetlov
Gregory P. Smith