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

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-156546

Comece em profiling/sampling/stack_collector.py, em FlamegraphCollector.export e na travessia convert_children correspondente. Reproduza com um programa profundamente recursivo cujo limite de recursão exceda a profundidade da pilha capturada, usando tanto --flamegraph quanto --diff-flamegraph. Está concluído quando ambos os caminhos de exportação produzirem um flamegraph sem RecursionError; revise o PR vinculado gh-156546 para ver o trabalho já em andamento.