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3d4ac1a2c2
Concurrent accesses from multiple threads to the same `cell` object did not scale well in the free-threaded build. Use `_PyStackRef` and optimistically avoid locking to improve scaling. With the locks around cell reads gone, some of the free threading tests were prone to starvation: the readers were able to run in a tight loop and the writer threads weren't scheduled frequently enough to make timely progress. Adjust the tests to avoid this. Co-authored-by: Donghee Na <donghee.na@python.org>
75 lines
1.7 KiB
C
75 lines
1.7 KiB
C
#ifndef Py_INTERNAL_CELL_H
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#define Py_INTERNAL_CELL_H
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#include "pycore_critical_section.h"
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#include "pycore_object.h"
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#include "pycore_stackref.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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#ifndef Py_BUILD_CORE
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# error "this header requires Py_BUILD_CORE define"
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#endif
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// Sets the cell contents to `value` and return previous contents. Steals a
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// reference to `value`.
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static inline PyObject *
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PyCell_SwapTakeRef(PyCellObject *cell, PyObject *value)
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{
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PyObject *old_value;
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Py_BEGIN_CRITICAL_SECTION(cell);
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old_value = cell->ob_ref;
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FT_ATOMIC_STORE_PTR_RELEASE(cell->ob_ref, value);
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Py_END_CRITICAL_SECTION();
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return old_value;
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}
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static inline void
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PyCell_SetTakeRef(PyCellObject *cell, PyObject *value)
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{
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PyObject *old_value = PyCell_SwapTakeRef(cell, value);
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Py_XDECREF(old_value);
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}
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// Gets the cell contents. Returns a new reference.
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static inline PyObject *
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PyCell_GetRef(PyCellObject *cell)
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{
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PyObject *res;
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Py_BEGIN_CRITICAL_SECTION(cell);
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#ifdef Py_GIL_DISABLED
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res = _Py_XNewRefWithLock(cell->ob_ref);
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#else
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res = Py_XNewRef(cell->ob_ref);
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#endif
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Py_END_CRITICAL_SECTION();
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return res;
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}
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static inline _PyStackRef
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_PyCell_GetStackRef(PyCellObject *cell)
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{
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PyObject *value;
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#ifdef Py_GIL_DISABLED
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value = _Py_atomic_load_ptr(&cell->ob_ref);
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if (value == NULL) {
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return PyStackRef_NULL;
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}
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_PyStackRef ref;
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if (_Py_TryIncrefCompareStackRef(&cell->ob_ref, value, &ref)) {
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return ref;
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}
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#endif
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value = PyCell_GetRef(cell);
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if (value == NULL) {
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return PyStackRef_NULL;
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}
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return PyStackRef_FromPyObjectSteal(value);
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}
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#ifdef __cplusplus
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}
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#endif
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#endif /* !Py_INTERNAL_CELL_H */
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