gh-116738: Make _heapq module thread-safe

Lib/test/test_free_threading/test_heapq.py

@@ -0,0 +1,255 @@
+import unittest
+
+import heapq
+import operator
+
+from enum import Enum
+from threading import Thread, Barrier
+from random import shuffle, randint
+
+from test.support import threading_helper
+
+
+NTHREADS = 10
+OBJECT_COUNT = 5_000
+
+
+class Heap(Enum):
+    MIN = 1
+    MAX = 2
+
+
+@threading_helper.requires_working_threading()
+class TestHeapq(unittest.TestCase):
+    def test_racing_heapify(self):
+        heap = list(range(OBJECT_COUNT))
+        shuffle(heap)
+
+        self.run_concurrently(
+            worker_func=heapq.heapify, args=(heap,), nthreads=NTHREADS
+        )
+        self.assertTrue(self.is_heap_property_satisfied(heap, Heap.MIN))
+
+    def test_racing_heappush(self):
+        heap = []
+
+        def heappush_func(heap):
+            for item in reversed(range(OBJECT_COUNT)):
+                heapq.heappush(heap, item)
+
+        self.run_concurrently(
+            worker_func=heappush_func, args=(heap,), nthreads=NTHREADS
+        )
+        self.assertTrue(self.is_heap_property_satisfied(heap, Heap.MIN))
+
+    def test_racing_heappop(self):
+        heap = self.create_heap(OBJECT_COUNT, Heap.MIN)
+
+        # Each thread pops (OBJECT_COUNT / NTHREADS) items
+        self.assertEqual(OBJECT_COUNT % NTHREADS, 0)
+        per_thread_pop_count = OBJECT_COUNT // NTHREADS
+
+        def heappop_func(heap, pop_count):
+            local_list = []
+            for _ in range(pop_count):
+                item = heapq.heappop(heap)
+                local_list.append(item)
+
+            # Each local list should be sorted
+            self.assertTrue(self.is_sorted_ascending(local_list))
+
+        self.run_concurrently(
+            worker_func=heappop_func,
+            args=(heap, per_thread_pop_count),
+            nthreads=NTHREADS,
+        )
+        self.assertEqual(len(heap), 0)
+
+    def test_racing_heappushpop(self):
+        heap = self.create_heap(OBJECT_COUNT, Heap.MIN)
+        pushpop_items = self.create_random_list(-5_000, 10_000, OBJECT_COUNT)
+
+        def heappushpop_func(heap, pushpop_items):
+            for item in pushpop_items:
+                popped_item = heapq.heappushpop(heap, item)
+                self.assertTrue(popped_item <= item)
+
+        self.run_concurrently(
+            worker_func=heappushpop_func,
+            args=(heap, pushpop_items),
+            nthreads=NTHREADS,
+        )
+        self.assertEqual(len(heap), OBJECT_COUNT)
+        self.assertTrue(self.is_heap_property_satisfied(heap, Heap.MIN))
+
+    def test_racing_heapreplace(self):
+        heap = self.create_heap(OBJECT_COUNT, Heap.MIN)
+        replace_items = self.create_random_list(-5_000, 10_000, OBJECT_COUNT)
+
+        def heapreplace_func(heap, replace_items):
+            for item in replace_items:
+                popped_item = heapq.heapreplace(heap, item)
+
+        self.run_concurrently(
+            worker_func=heapreplace_func,
+            args=(heap, replace_items),
+            nthreads=NTHREADS,
+        )
+        self.assertEqual(len(heap), OBJECT_COUNT)
+        self.assertTrue(self.is_heap_property_satisfied(heap, Heap.MIN))
+
+    def test_racing_heapify_max(self):
+        max_heap = list(range(OBJECT_COUNT))
+        shuffle(max_heap)
+
+        self.run_concurrently(
+            worker_func=heapq.heapify_max, args=(max_heap,), nthreads=NTHREADS
+        )
+        self.assertTrue(self.is_heap_property_satisfied(max_heap, Heap.MAX))
+
+    def test_racing_heappush_max(self):
+        max_heap = []
+
+        def heappush_max_func(max_heap):
+            for item in range(OBJECT_COUNT):
+                heapq.heappush_max(max_heap, item)
+
+        self.run_concurrently(
+            worker_func=heappush_max_func, args=(max_heap,), nthreads=NTHREADS
+        )
+        self.assertTrue(self.is_heap_property_satisfied(max_heap, Heap.MAX))
+
+    def test_racing_heappop_max(self):
+        max_heap = self.create_heap(OBJECT_COUNT, Heap.MAX)
+
+        # Each thread pops (OBJECT_COUNT / NTHREADS) items
+        self.assertEqual(OBJECT_COUNT % NTHREADS, 0)
+        per_thread_pop_count = OBJECT_COUNT // NTHREADS
+
+        def heappop_max_func(max_heap, pop_count):
+            local_list = []
+            for _ in range(pop_count):
+                item = heapq.heappop_max(max_heap)
+                local_list.append(item)
+
+            # Each local list should be sorted
+            self.assertTrue(self.is_sorted_descending(local_list))
+
+        self.run_concurrently(
+            worker_func=heappop_max_func,
+            args=(max_heap, per_thread_pop_count),
+            nthreads=NTHREADS,
+        )
+        self.assertEqual(len(max_heap), 0)
+
+    def test_racing_heappushpop_max(self):
+        max_heap = self.create_heap(OBJECT_COUNT, Heap.MAX)
+        pushpop_items = self.create_random_list(-5_000, 10_000, OBJECT_COUNT)
+
+        def heappushpop_max_func(max_heap, pushpop_items):
+            for item in pushpop_items:
+                popped_item = heapq.heappushpop_max(max_heap, item)
+                self.assertTrue(popped_item >= item)
+
+        self.run_concurrently(
+            worker_func=heappushpop_max_func,
+            args=(max_heap, pushpop_items),
+            nthreads=NTHREADS,
+        )
+        self.assertEqual(len(max_heap), OBJECT_COUNT)
+        self.assertTrue(self.is_heap_property_satisfied(max_heap, Heap.MAX))
+
+    def test_racing_heapreplace_max(self):
+        max_heap = self.create_heap(OBJECT_COUNT, Heap.MAX)
+        replace_items = self.create_random_list(-5_000, 10_000, OBJECT_COUNT)
+
+        def heapreplace_max_func(max_heap, replace_items):
+            for item in replace_items:
+                popped_item = heapq.heapreplace_max(max_heap, item)
+
+        self.run_concurrently(
+            worker_func=heapreplace_max_func,
+            args=(max_heap, replace_items),
+            nthreads=NTHREADS,
+        )
+        self.assertEqual(len(max_heap), OBJECT_COUNT)
+        self.assertTrue(self.is_heap_property_satisfied(max_heap, Heap.MAX))
+
+    @staticmethod
+    def is_heap_property_satisfied(heap, heap_kind):
+        """
+        Check if the heap property is satisfied.
+        MIN-Heap: The value of a parent node should be less than or equal to the
+        values of its children.
+        MAX-Heap: The value of a parent node should be greater than or equal to the
+        values of its children.
+        """
+        op = operator.le if heap_kind == Heap.MIN else operator.ge
+        # position 0 has no parent
+        for pos in range(1, len(heap)):
+            parent_pos = (pos - 1) >> 1
+            if not op(heap[parent_pos], heap[pos]):
+                return False
+
+        return True
+
+    @staticmethod
+    def is_sorted_ascending(lst):
+        """
+        Check if the list is sorted in ascending order (non-decreasing).
+        """
+        return all(lst[i - 1] <= lst[i] for i in range(1, len(lst)))
+
+    @staticmethod
+    def is_sorted_descending(lst):
+        """
+        Check if the list is sorted in descending order (non-increasing).
+        """
+        return all(lst[i - 1] >= lst[i] for i in range(1, len(lst)))
+
+    @staticmethod
+    def create_heap(size, heap_kind):
+        """
+        Create a min/max heap where elements are in the range (0, size - 1) and
+        shuffled before heapify.
+        """
+        heap = list(range(OBJECT_COUNT))
+        shuffle(heap)
+        if heap_kind == Heap.MIN:
+            heapq.heapify(heap)
+        else:
+            heapq.heapify_max(heap)
+
+        return heap
+
+    @staticmethod
+    def create_random_list(a, b, size):
+        """
+        Create a list of random numbers between a and b (inclusive).
+        """
+        return [randint(-a, b) for _ in range(size)]
+
+    def run_concurrently(self, worker_func, args, nthreads) -> None:
+        """
+        Run the worker function concurrently in multiple threads.
+        """
+        barrier = Barrier(nthreads)
+
+        def wrapper_func(*args):
+            # Wait for all threadss to reach this point before proceeding.
+            barrier.wait()
+            worker_func(*args)
+
+        with threading_helper.catch_threading_exception() as cm:
+            workers = (
+                Thread(target=wrapper_func, args=args) for _ in range(nthreads)
+            )
+            with threading_helper.start_threads(workers):
+                pass
+
+            # Worker threads should not raise any exceptions
+            self.assertIsNone(cm.exc_value)
+
+
+if __name__ == "__main__":
+    unittest.main()

Misc/NEWS.d/next/Core_and_Builtins/2025-06-02-13-57-40.gh-issue-116738.ycJsL8.rst

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+Make methods in :mod:`heapq` thread-safe on the :term:`free threaded <free threading>` build.