gh-138122: Implement PEP 799 (#138142)

Lib/profiling/sampling/stack_collector.py

@@ -0,0 +1,37 @@
+import collections
+import os
+
+from .collector import Collector
+
+
+class StackTraceCollector(Collector):
+    def __init__(self):
+        self.call_trees = []
+        self.function_samples = collections.defaultdict(int)
+
+    def collect(self, stack_frames):
+        for thread_id, frames in stack_frames:
+            if frames:
+                # Store the complete call stack (reverse order - root first)
+                call_tree = list(reversed(frames))
+                self.call_trees.append(call_tree)
+
+                # Count samples per function
+                for frame in frames:
+                    self.function_samples[frame] += 1
+
+
+class CollapsedStackCollector(StackTraceCollector):
+    def export(self, filename):
+        stack_counter = collections.Counter()
+        for call_tree in self.call_trees:
+            # Call tree is already in root->leaf order
+            stack_str = ";".join(
+                f"{os.path.basename(f[0])}:{f[2]}:{f[1]}" for f in call_tree
+            )
+            stack_counter[stack_str] += 1
+
+        with open(filename, "w") as f:
+            for stack, count in stack_counter.items():
+                f.write(f"{stack} {count}\n")
+        print(f"Collapsed stack output written to {filename}")