ij"dZddlZddlZddlZddlZddlZeejjddZ e ejjddZ dZ Gdd Z d Zd Zd Zed k(reej$dyy)aTReproducer for the free-threaded GC crash in issue #515. https://github.com/python-greenlet/greenlet/issues/515 Before the fix, ``set_initial_state`` copied the parent thread state's ``_PyCStackRef`` list head into each new greenlet. Those nodes sit on the parent greenlet's C stack, so once the child starts running on its own stack and overwrites that region their ``next`` pointers dangle. The free-threaded collector walks ``c_stack_refs`` for every thread, so a GC on any thread ends up chasing those dangling nodes (inside ``gc_collect_main`` -> ``gc_visit_thread_stacks``) while such a child is active, and segfaults. The fiddly part is getting a *non-empty* list to inherit at all. The interpreter only holds a ``_PyCStackRef`` transiently, while it is resolving an attribute -- ``_Py_LoadAttr_StackRefSteal`` pins ``self`` across ``obj.attr()`` -- so the greenlet has to be primed from inside that window. Priming it from a property getter does exactly that; it is also the same deep-attribute context Playwright's sync bridge happens to start its fiber from. A churn thread then keeps the collector busy while the dispatcher runs on its stale list. A fixed build prints "ISSUE 515 OK"; a regressed one segfaults in about a second. With-GIL builds are unaffected -- ordinary refcounting keeps the nodes alive -- so there it simply prints the OK line. N REPRO_SECONDS4 REPRO_THREADS6cvdjjjjS)Nabc)upperlowerstriptitle^/root/.hermes/venv/lib/python3.12/site-packages/greenlet/tests/fail_issue_515_freethread_gc.py_busyr&s+ ;;=   & & ( . . 00rc4eZdZdZdZedZdZdZy)Bridgec||_tj|_tj|j|_yN)stopgreenlet getcurrentmain_loopdisp)selfrs r__init__zBridge.__init__-s/ '') %%djj1 rc|jdsEtdD] }t|jj |jdsDyy)Nr2)rrangerrswitch)r_s rrz Bridge._loop2sB))A,2Y   II   ))A,rc8|jjyrrr rs r_primez Bridge._prime8s rc|jSr)r%r$s rstartz Bridge.start@s {{rc8|jjyrr#r$s rresumez Bridge.resumeGs rN) __name__ __module__ __qualname__rrpropertyr%r'r)r rrrr,s*2  rrcrt|}|j|ds|j|dsyy)Nr)rr'r))rbridges rworkerr0Ks/ D\F LLN1g 1grc|ds^tdDcgc]}|dd }}t||ddD] \}}||d< |d|dd<~tj|ds]yycc}w)Nri)inextr3)rzipgccollect)rr2nodesabs rchurnr<Ts|1g27srVs0  5 6 rzz~~os3 41 >   zF CHHQKr