[pypy-issue] Issue #2786: pypy3 interpreter segfault somewhere around async/gc/finalization (pypy/pypy)

[Joshua Oreman]

New issue 2786: pypy3 interpreter segfault somewhere around async/gc/finalization
https://bitbucket.org/pypy/pypy/issues/2786/pypy3-interpreter-segfault-somewhere

Joshua Oreman:

The async_generator package provides pure-Python async generators with semantics as similar as possible to the native ones in CPython 3.6, with the goal of supporting PyPy and CPython 3.5. It's located at https://github.com/python-trio/async_generator.

I'm working on adding support to async_generator for PEP 525 finalization hooks, and ran into a PyPy interpreter crash. I've merged all the dependencies into one file without any CPython-specifics, and it still reliably reproduces the crash, with or without `--jit off`; it's attached below. (The full change from which this was extracted is https://github.com/python-trio/async_generator/pull/14; it's not merged into async_generator yet.)

I'm using OS X 10.13.3, with pypy3 installed using Homebrew:
```
$ pypy3 asyncgenissue.py
mock_sleep
mock_sleep
Segmentation fault: 11

$ pypy3
Python 3.5.3 (3f6eaa010fce78cc7973bdc1dfdb95970f08fed2, Jan 13 2018, 18:14:01)
[PyPy 5.10.1 with GCC 4.2.1 Compatible Apple LLVM 9.0.0 (clang-900.0.39.2)]
>>> print("\n".join("{}: {}".format(*elem) for elem in __import__("sys").pypy_translation_info.items()))
objspace.usemodules.__builtin__: False
[lots of other objspace.usemodules.something: True]
objspace.usemodules.micronumpy: False
objspace.allworkingmodules: True
objspace.extmodules: None
objspace.translationmodules: False
objspace.soabi: None
objspace.honor__builtins__: False
objspace.disable_call_speedhacks: False
objspace.disable_entrypoints: False
objspace.fstrings: True
objspace.hash: siphash24
objspace.std.withtproxy: True
objspace.std.withprebuiltint: False
objspace.std.prebuiltintfrom: -5
objspace.std.prebuiltintto: 100
objspace.std.withsmalllong: False
objspace.std.withspecialisedtuple: True
objspace.std.withliststrategies: True
objspace.std.withmethodcachecounter: False
objspace.std.methodcachesizeexp: 11
objspace.std.intshortcut: True
objspace.std.optimized_list_getitem: True
objspace.std.newshortcut: False
translating: True
translation.continuation: True
translation.type_system: lltype
translation.backend: c
translation.shared: True
translation.log: True
translation.gc: incminimark
translation.gctransformer: framework
translation.gcremovetypeptr: True
translation.gcrootfinder: shadowstack
translation.thread: True
translation.sandbox: False
translation.rweakref: True
translation.jit: True
translation.jit_backend: auto
translation.jit_profiler: off
translation.jit_opencoder_model: normal
translation.check_str_without_nul: True
translation.verbose: True
translation.cc: clang
translation.profopt: False
translation.profoptargs: None
translation.instrument: False
translation.countmallocs: False
translation.fork_before: None
translation.dont_write_c_files: False
translation.instrumentctl: None
translation.output: None
translation.secondaryentrypoints: cpyext,main
translation.dump_static_data_info: False
translation.no__thread: True
translation.make_jobs: 3
translation.list_comprehension_operations: True
translation.withsmallfuncsets: 5
translation.taggedpointers: False
translation.keepgoing: False
translation.lldebug: False
translation.lldebug0: False
translation.lto: False
translation.icon: pypy.ico
translation.libname: None
translation.backendopt.inline: True
translation.backendopt.inline_threshold: 32.4
translation.backendopt.inline_heuristic: rpython.translator.backendopt.inline.inlining_heuristic
translation.backendopt.print_statistics: False
translation.backendopt.merge_if_blocks: True
translation.backendopt.mallocs: True
translation.backendopt.constfold: True
translation.backendopt.profile_based_inline: None
translation.backendopt.profile_based_inline_threshold: 32.4
translation.backendopt.profile_based_inline_heuristic: rpython.translator.backendopt.inline.inlining_heuristic
translation.backendopt.clever_malloc_removal: False
translation.backendopt.clever_malloc_removal_threshold: 32.4
translation.backendopt.clever_malloc_removal_heuristic: rpython.translator.backendopt.inline.inlining_heuristic
translation.backendopt.remove_asserts: False
translation.backendopt.really_remove_asserts: False
translation.backendopt.stack_optimization: True
translation.backendopt.storesink: True
translation.backendopt.replace_we_are_jitted: False
translation.backendopt.none: None
translation.platform: host
```

I gave about an hour's effort to trying to get a debug version of pypy translated, and gave up when I got `[translation:ERROR] Exception: 'no_collect' function can trigger collection: <function _siphash24 at 0x000000010b2afcb8>`.