René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Python 3.14 stack overflow detection is incompatible with C++ Boost make_fcontext() coroutines","articleBody":"Python 3.14 introduced a new stack overflow detection mecanism: [InternalDocs/stack_protection.md](https://github.com/python/cpython/blob/main/InternalDocs/stack_protection.md) (#130396).\n\nThe KiCad application uses C++ Boost `make_fcontext()` coroutines which runs coroutine in **their own stack**.\n\nCode example from [fcontext doc](https://www.boost.org/doc/libs/1_59_0/libs/context/doc/html/context/context.html):\n\n```c++\n// context-function\nvoid f(intptr);\n\n// creates a new stack\nstd::size_t size = 8192;\nvoid* sp(std::malloc(size));\n\n// context fc uses f() as context function\n// fcontext_t is placed on top of context stack\n// a pointer to fcontext_t is returned\nfcontext_t fc(make_fcontext(sp,size,f));\n```\n\n`_Py_InitializeRecursionLimits()` is called in the main thread, whereas `_Py_CheckRecursiveCall()` is called for the first time in a coroutine (`make_fcontext()`).\n\n**Problem:** Python **detects a stack overflow** because it's not aware that the stack base address and size changed when `make_fcontext()` was called.\n\n`pthread` functions such as `pthread_attr_getguardsize()` are incompatible with `make_fcontext()`.\n\ncc @markshannon \n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-139667\n* gh-139668\n* gh-141551\n* gh-141661\n* gh-141711\n* gh-141892\n* gh-141944\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/vstinner","@type":"Person","name":"vstinner"},"datePublished":"2025-10-06T12:31:52.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":29},"url":"https://github.com/139653/cpython/issues/139653"}