The REPL hangs under no memory on 3.13

[ZeroIntensity]

Bug report

Bug description:

In the new REPL, failing allocations seem to cause the prompt to get stuck:

>>> import _testcapi
>>> _testcapi.set_nomemory(0)  # Now wait forever

I don't expect it to be able to work under no memory, but I do expect it to at least crash gracefully. The basic REPL spits this out before exiting:

object address  : 0x7f02f532d180
object refcount : 3
object type     : 0x7f02f5ec7780
object type name: MemoryError
object repr     : 
lost sys.stderr

Ideally, the new REPL should do something similar. This isn't at all a priority, but something fun for anyone bored and willing to take a stab at it.

CPython versions tested on:

3.13

Operating systems tested on:

Linux

Linked PRs

• [3.13] gh-134163: fix: exec('_testcapi.set_nomemory(0)') hang in new repl 3.13 #138491

[sergey-miryanov]

On windows 11 it works as expected (virtual terminal support on)

 [2025-05-18 15:21:11] [D:\Sources\_pythonish\cpython\main]  [main ≡ +17 ~10 -0 !] [󰅒 1:56.656]
➜ .\python.bat
Running Release|x64 interpreter...
Python 3.15.0a0 (heads/main-dirty:0a160bf14c4, May 18 2025, 15:19:49) [MSC v.1943 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import _testcapi
>>> _testcapi.set_nomemory(0)
object address  : 00000269B229DF00
object refcount : 3
object type     : 00007FF8887AFDF0
object type name: MemoryError
object repr     :
lost sys.stderr

[donBarbos]

On windows 11 it works as expected (virtual terminal support on)

I also didn't get any hangs either using ./configure --with-pydebug && make on Linux (I tested on gcc and clang):

>>> _testcapi.set_nomemory(0)
object address  : 0x79d5e61a42f0
object refcount : 3
object type     : 0x591fb1b34f40
object type name: MemoryError
object repr     :
lost sys.stderr

[ZeroIntensity]

Ah, I screwed up when testing. 3.14 and 3.15 do exhibit the correct behavior, but not 3.13. My bad!