vm: add per-interpreter runtime state and interpreter registry

- vm/runtime.rs: process-global interpreter registry (monotonic ids, weak entries), InterpreterWhence/InterpreterInfo, process main id recording via main_interpreter_id(), a threading-gated owner map (store_owned_interpreter/ take_owned_interpreter/is_owned_interpreter/owned_interpreter_count), and the SUPPORTS_ISOLATED_INTERPRETERS constant. - PyGlobalState gains interpreter_id/whence/is_main and is_main_interpreter(); PyConfig/Settings derive Clone so a subinterpreter can clone parent config. - Interpreter: id()/whence()/is_main()/is_process_main(), create_subinterpreter() and create_owned_subinterpreter(); unregister on Drop. - thread.rs: per-interpreter thread slots (INTERP_THREAD_SLOTS), slot swap when switching interpreters on one OS thread, cleanup keyed by interpreter id. - Install signal handlers and init the main-thread ident only on the main interpreter; _thread._is_main_interpreter reflects the current interpreter. - sys.implementation.supports_isolated_interpreters reads the constant. - Guard the registry static for non-threading builds where rc::Weak is !Send. Assisted-by: Claude Code:claude-opus-4-8
youknowone · Aug 16, 2026 · Aug 13, 2026 · Aug 13, 2026 · Aug 13, 2026 · Aug 13, 2026
commit 5c341d263e9b14263fa2b77046c2d46a2bd44f2c
diff --git a/crates/vm/src/lib.rs b/crates/vm/src/lib.rs
@@ -109,7 +109,11 @@ pub use self::object::{
     AsObject, Py, PyAtomicRef, PyExact, PyObject, PyObjectRef, PyPayload, PyRef, PyRefExact,
     PyResult, PyStackRef, PyWeakRef,
 };
-pub use self::vm::{Context, Interpreter, InterpreterBuilder, Settings, VirtualMachine};
+pub use self::vm::runtime;
+pub use self::vm::{
+    Context, Interpreter, InterpreterBuilder, InterpreterInfo, InterpreterWhence,
+    MAIN_INTERPRETER_ID, Settings, VirtualMachine,
+};
 
 pub use rustpython_common as common;
 pub use rustpython_compiler_core::{bytecode, frozen};

diff --git a/crates/vm/src/stdlib/_signal.rs b/crates/vm/src/stdlib/_signal.rs
@@ -177,7 +177,9 @@ pub(crate) mod _signal {
         module: &Py<crate::builtins::PyModule>,
         vm: &VirtualMachine,
     ) {
-        if vm.state.config.settings.install_signal_handlers {
+        // Process-global signal disposition is owned by the main interpreter only.
+        // Subinterpreters (PEP 734) must not reinstall SIGINT / probe handlers.
+        if vm.state.is_main_interpreter() && vm.state.config.settings.install_signal_handlers {
             let sig_dfl = vm.new_pyobj(SIG_DFL as u8);
             let sig_ign = vm.new_pyobj(SIG_IGN as u8);
 

diff --git a/crates/vm/src/stdlib/_thread.rs b/crates/vm/src/stdlib/_thread.rs
@@ -796,9 +796,8 @@ pub(crate) mod _thread {
     }
 
     #[pyfunction]
-    fn _is_main_interpreter() -> bool {
-        // RustPython only has one interpreter
-        true
+    fn _is_main_interpreter(vm: &VirtualMachine) -> bool {
+        vm.state.is_main_interpreter()
     }
 
     /// Initialize the main thread ident. Should be called once at interpreter startup.

diff --git a/crates/vm/src/stdlib/sys.rs b/crates/vm/src/stdlib/sys.rs
@@ -669,7 +669,8 @@ pub mod sys {
             "_multiarch" => ctx.new_str(multiarch()),
             "version" => PyVersionInfo::from_data(VersionInfoData::IMPLEMENTATION, vm),
             "hexversion" => ctx.new_int(version::VERSION_HEX_IMPL),
-            "supports_isolated_interpreters" => ctx.new_bool(false),
+            "supports_isolated_interpreters" =>
+                ctx.new_bool(crate::vm::runtime::SUPPORTS_ISOLATED_INTERPRETERS),
         })
     }