profiling: flamegraph export fails with RecursionError on a deeply recursive program

[tonghuaroot]

Bug report

Bug description:

The sampling profiler's flamegraph export (profiling.sampling.stack_collector.FlamegraphCollector.export) builds the flamegraph tree with a recursive walk (convert_children) and then serializes it with json.dumps — both recurse to the depth of the deepest sampled stack. The remote unwinder captures up to MAX_FRAMES (1536) frames, but export runs at the default recursion limit (1000), so profiling a program that recurses deeper than ~1000 makes export() raise RecursionError and write no flamegraph. Both --flamegraph and --diff-flamegraph are affected (the diff collector inherits export).

Reachable when profiling a program that raised its own recursion limit and recurses deeply (recursive-descent parsers, tree/graph walkers, deep serializers).

CPython versions tested on:

CPython main

Operating systems tested on:

Linux, macOS

Linked PRs

• gh-156545: Fix flamegraph export RecursionError on deeply recursive programs #156546
• [3.15] gh-156545: Fix flamegraph export RecursionError on deeply recursive programs (GH-156546) #158851
• gh-156545, gh-158539: Fix deep flamegraph export on small C stacks and macOS runtime lookup #158874