attempt to declare subinterpreter compatibility

CMakeLists.txt

@@ -406,6 +406,7 @@ if (NOT PYZMQ_BACKEND)
     set(PYZMQ_BACKEND "cffi")
   else()
     set(PYZMQ_BACKEND "cython")
+    add_compile_definitions(CYTHON_USE_MODULE_STATE=1)
   endif()
 endif()
 

tests/test_subshell.py

@@ -0,0 +1,36 @@
+import sys
+
+import pytest
+from conftest import recv
+
+import zmq
+
+if sys.version_info < (3, 14):
+    pytest.skip("Requires Python 3.14")
+
+from concurrent.futures import InterpreterPoolExecutor
+
+
+def echo(url):
+    with zmq.Context() as ctx, ctx.socket(zmq.ROUTER) as s:
+        s.bind(url)
+        msg = s.recv_multipart()
+        print(msg)
+
+
+def test_subshell(context, socket):
+    s = socket(zmq.DEALER)
+    url = "tcp://127.0.0.1:5555"
+    with InterpreterPoolExecutor(1) as pool:
+        f = pool.submit(echo, url)
+        try:
+            f.result(timeout=1)
+        except TimeoutError:
+            pass
+        else:
+            pytest.fail("echo task exited prematurely...")
+        s.connect(url)
+        msg = b"msg"
+        s.send(msg)
+        recvd = recv(s)
+        assert recvd == msg

zmq/backend/cython/_zmq.py

@@ -1,5 +1,7 @@
 # cython: language_level = 3str
 # cython: freethreading_compatible = True
+# cython: subinterpreters_compatible = own_gil
+
 """Cython backend for pyzmq"""
 
 # Copyright (C) PyZMQ Developers
@@ -49,6 +51,7 @@
     cfunc,
     char,
     declare,
+    exceptval,
     inline,
     nogil,
     p_char,
@@ -169,7 +172,7 @@
 
 @cfunc
 @inline
-@C.exceptval(-1)
+@exceptval(-1)
 def _check_rc(rc: C.int, error_without_errno: bint = False) -> C.int:
     """internal utility for checking zmq return condition
 
@@ -1804,6 +1807,7 @@ def proxy_steerable(
 @cfunc
 @inline
 @nogil
+@exceptval(check=False)
 def _mq_relay(
     in_socket: p_void,
     out_socket: p_void,
@@ -1887,6 +1891,7 @@ def _mq_relay(
 @cfunc
 @inline
 @nogil
+@exceptval(check=False)
 def _mq_inline(
     in_socket: p_void,
     out_socket: p_void,