micropython · dpgeorge · Jul 23, 2025 · Jul 15, 2025 · Jul 10, 2025 · Jul 10, 2025
diff --git a/docs/library/sys.rst b/docs/library/sys.rst
@@ -77,6 +77,8 @@ Constants
    * *_mpy* - supported mpy file-format version (optional attribute)
    * *_build* - string that can help identify the configuration that
      MicroPython was built with
+   * *_thread* - optional string attribute, exists if the target has threading
+     and is either "GIL" or "unsafe"
 
    This object is the recommended way to distinguish MicroPython from other
    Python implementations (note that it still may not exist in the very
@@ -95,6 +97,14 @@ Constants
    * On microcontroller targets, the first element is the board name and the second
      element (if present) is the board variant, for example ``'RPI_PICO2-RISCV'``
 
+   The *_thread* entry was added in version 1.26.0 and if it exists then the
+   target has the ``_thread`` module.  If the target enables the GIL (global
+   interpreter lock) then this attribute is ``"GIL"``.  Otherwise the attribute
+   is ``"unsafe"`` and the target has threading but does not enable the GIL,
+   and mutable Python objects (such as `bytearray`, `list` and `dict`) that are
+   shared amongst threads must be protected explicitly by locks such as
+   ``_thread.allocate_lock``.
+
    .. admonition:: Difference to CPython
       :class: attention
 

diff --git a/ports/unix/Makefile b/ports/unix/Makefile
@@ -259,7 +259,6 @@ test: $(BUILD)/$(PROG) $(TOP)/tests/run-tests.py
 test_full_no_native: $(BUILD)/$(PROG) $(TOP)/tests/run-tests.py
 	$(eval DIRNAME=ports/$(notdir $(CURDIR)))
 	cd $(TOP)/tests && MICROPY_MICROPYTHON=../$(DIRNAME)/$(BUILD)/$(PROG) ./run-tests.py
-	cd $(TOP)/tests && MICROPY_MICROPYTHON=../$(DIRNAME)/$(BUILD)/$(PROG) ./run-tests.py -d thread
 	cd $(TOP)/tests && MICROPY_MICROPYTHON=../$(DIRNAME)/$(BUILD)/$(PROG) ./run-tests.py --via-mpy $(RUN_TESTS_MPY_CROSS_FLAGS) -d basics float micropython
 	cat $(TOP)/tests/basics/0prelim.py | ./$(BUILD)/$(PROG) | grep -q 'abc'
 

diff --git a/py/modsys.c b/py/modsys.c
@@ -103,6 +103,18 @@ static const MP_DEFINE_STR_OBJ(mp_sys_implementation__build_obj, MICROPY_BOARD_B
 #define SYS_IMPLEMENTATION_ELEMS__BUILD
 #endif
 
+#if MICROPY_PY_THREAD
+#if MICROPY_PY_THREAD_GIL
+#define SYS_IMPLEMENTATION_ELEMS__THREAD \
+    , MP_ROM_QSTR(MP_QSTR_GIL)
+#else
+#define SYS_IMPLEMENTATION_ELEMS__THREAD \
+    , MP_ROM_QSTR(MP_QSTR_unsafe)
+#endif
+#else
+#define SYS_IMPLEMENTATION_ELEMS__THREAD
+#endif
+
 #if MICROPY_PREVIEW_VERSION_2
 #define SYS_IMPLEMENTATION_ELEMS__V2 \
     , MP_ROM_TRUE
@@ -120,27 +132,31 @@ static const qstr impl_fields[] = {
     #if defined(MICROPY_BOARD_BUILD_NAME)
     MP_QSTR__build,
     #endif
+    #if MICROPY_PY_THREAD
+    MP_QSTR__thread,
+    #endif
     #if MICROPY_PREVIEW_VERSION_2
     MP_QSTR__v2,
     #endif
 };
 static MP_DEFINE_ATTRTUPLE(
     mp_sys_implementation_obj,
     impl_fields,
-    3 + MICROPY_PERSISTENT_CODE_LOAD + MICROPY_BOARD_BUILD + MICROPY_PREVIEW_VERSION_2,
+    3 + MICROPY_PERSISTENT_CODE_LOAD + MICROPY_BOARD_BUILD + MICROPY_PY_THREAD + MICROPY_PREVIEW_VERSION_2,
     SYS_IMPLEMENTATION_ELEMS_BASE
     SYS_IMPLEMENTATION_ELEMS__MPY
     SYS_IMPLEMENTATION_ELEMS__BUILD
+    SYS_IMPLEMENTATION_ELEMS__THREAD
     SYS_IMPLEMENTATION_ELEMS__V2
     );
 #else
 static const mp_rom_obj_tuple_t mp_sys_implementation_obj = {
     {&mp_type_tuple},
     3 + MICROPY_PERSISTENT_CODE_LOAD,
-    // Do not include SYS_IMPLEMENTATION_ELEMS__BUILD or SYS_IMPLEMENTATION_ELEMS__V2
-    // because SYS_IMPLEMENTATION_ELEMS__MPY may be empty if
+    // Do not include SYS_IMPLEMENTATION_ELEMS__BUILD, SYS_IMPLEMENTATION_ELEMS__THREAD
+    // or SYS_IMPLEMENTATION_ELEMS__V2 because SYS_IMPLEMENTATION_ELEMS__MPY may be empty if
     // MICROPY_PERSISTENT_CODE_LOAD is disabled, which means they'll share
-    // the same index. Cannot query _build or _v2 if MICROPY_PY_ATTRTUPLE is
+    // the same index. Cannot query _build, _thread or _v2 if MICROPY_PY_ATTRTUPLE is
     // disabled.
     {
         SYS_IMPLEMENTATION_ELEMS_BASE

diff --git a/tests/basics/sys1.py b/tests/basics/sys1.py
@@ -30,6 +30,12 @@
     # Effectively skip subtests
     print(str)
 
+if hasattr(sys.implementation, '_thread'):
+    print(sys.implementation._thread in ("GIL", "unsafe"))
+else:
+    # Effectively skip subtests
+    print(True)
+
 try:
     print(sys.intern('micropython') == 'micropython')
     has_intern = True

diff --git a/tests/extmod/select_poll_eintr.py b/tests/extmod/select_poll_eintr.py
@@ -33,6 +33,14 @@ def thread_main():
     print("thread gc end")
 
 
+# Pre-allocate global variables here so the global dict is not resized by the main
+# thread while the secondary thread runs.  This is a workaround for the bug described
+# in https://github.com/micropython/micropython/pull/11604
+poller = None
+t0 = None
+result = None
+dt_ms = None
+
 # Start a thread to interrupt the main thread during its call to poll.
 lock = _thread.allocate_lock()
 lock.acquire()

diff --git a/tests/feature_check/target_info.py b/tests/feature_check/target_info.py
@@ -20,4 +20,6 @@
     "xtensawin",
     "rv32imc",
 ][sys_mpy >> 10]
-print(platform, arch)
+thread = getattr(sys.implementation, "_thread", None)
+
+print(platform, arch, thread)
diff --git a/tests/run-tests.py b/tests/run-tests.py
@@ -251,22 +251,27 @@ def detect_test_platform(pyb, args):
     output = run_feature_check(pyb, args, "target_info.py")
     if output.endswith(b"CRASH"):
         raise ValueError("cannot detect platform: {}".format(output))
-    platform, arch = str(output, "ascii").strip().split()
+    platform, arch, thread = str(output, "ascii").strip().split()
     if arch == "None":
         arch = None
     inlineasm_arch = detect_inline_asm_arch(pyb, args)
+    if thread == "None":
+        thread = None
 
     args.platform = platform
     args.arch = arch
     if arch and not args.mpy_cross_flags:
         args.mpy_cross_flags = "-march=" + arch
     args.inlineasm_arch = inlineasm_arch
+    args.thread = thread
 
     print("platform={}".format(platform), end="")
     if arch:
         print(" arch={}".format(arch), end="")
     if inlineasm_arch:
         print(" inlineasm={}".format(inlineasm_arch), end="")
+    if thread:
+        print(" thread={}".format(thread), end="")
     print()
 
 
@@ -810,8 +815,8 @@ def run_tests(pyb, tests, args, result_dir, num_threads=1):
         skip_tests.add("cmdline/repl_sys_ps1_ps2.py")
         skip_tests.add("extmod/ssl_poll.py")
 
-    # Skip thread mutation tests on targets that don't have the GIL.
-    if args.platform in PC_PLATFORMS + ("rp2",):
+    # Skip thread mutation tests on targets that have unsafe threading behaviour.
+    if args.thread == "unsafe":
         for t in tests:
             if t.startswith("thread/mutate_"):
                 skip_tests.add(t)
@@ -1329,6 +1334,8 @@ def main():
             )
             if args.inlineasm_arch is not None:
                 test_dirs += ("inlineasm/{}".format(args.inlineasm_arch),)
+            if args.thread is not None:
+                test_dirs += ("thread",)
             if args.platform == "pyboard":
                 # run pyboard tests
                 test_dirs += ("float", "stress", "ports/stm32")
@@ -1337,9 +1344,9 @@ def main():
             elif args.platform == "renesas-ra":
                 test_dirs += ("float", "ports/renesas-ra")
             elif args.platform == "rp2":
-                test_dirs += ("float", "stress", "thread", "ports/rp2")
+                test_dirs += ("float", "stress", "ports/rp2")
             elif args.platform == "esp32":
-                test_dirs += ("float", "stress", "thread")
+                test_dirs += ("float", "stress")
             elif args.platform in ("esp8266", "minimal", "samd", "nrf"):
                 test_dirs += ("float",)
             elif args.platform == "WiPy":

diff --git a/tests/thread/stress_aes.py b/tests/thread/stress_aes.py
@@ -277,7 +277,7 @@ def thread_entry(n_loop):
         n_thread = 2
         n_loop = 2
     else:
-        n_thread = 20
+        n_thread = 10
         n_loop = 5
     for i in range(n_thread):
         _thread.start_new_thread(thread_entry, (n_loop,))

diff --git a/tools/ci.sh b/tools/ci.sh
@@ -720,7 +720,8 @@ function ci_unix_stackless_clang_build {
 }
 
 function ci_unix_stackless_clang_run_tests {
-    ci_unix_run_tests_helper CC=clang
+    # Timeout needs to be increased for thread/stress_aes.py test.
+    MICROPY_TEST_TIMEOUT=90 ci_unix_run_tests_helper CC=clang
 }
 
 function ci_unix_float_clang_build {
@@ -779,7 +780,8 @@ function ci_unix_macos_run_tests {
     # Issues with macOS tests:
     # - float_parse and float_parse_doubleprec parse/print floats out by a few mantissa bits
     # - ffi_callback crashes for an unknown reason
-    (cd tests && MICROPY_MICROPYTHON=../ports/unix/build-standard/micropython ./run-tests.py --exclude '(float_parse|float_parse_doubleprec|ffi_callback).py')
+    # - thread/stress_heap.py is flaky
+    (cd tests && MICROPY_MICROPYTHON=../ports/unix/build-standard/micropython ./run-tests.py --exclude '(float_parse|float_parse_doubleprec|ffi_callback|thread/stress_heap).py')
 }
 
 function ci_unix_qemu_mips_setup {
@@ -797,8 +799,11 @@ function ci_unix_qemu_mips_build {
 }
 
 function ci_unix_qemu_mips_run_tests {
+    # Issues with MIPS tests:
+    # - thread/stress_aes.py takes around 50 seconds
+    # - thread/stress_recurse.py is flaky
     file ./ports/unix/build-coverage/micropython
-    (cd tests && MICROPY_MICROPYTHON=../ports/unix/build-coverage/micropython ./run-tests.py)
+    (cd tests && MICROPY_MICROPYTHON=../ports/unix/build-coverage/micropython MICROPY_TEST_TIMEOUT=90 ./run-tests.py --exclude 'thread/stress_recurse.py')
 }
 
 function ci_unix_qemu_arm_setup {
@@ -818,8 +823,10 @@ function ci_unix_qemu_arm_build {
 function ci_unix_qemu_arm_run_tests {
     # Issues with ARM tests:
     # - (i)listdir does not work, it always returns the empty list (it's an issue with the underlying C call)
+    # - thread/stress_aes.py takes around 70 seconds
+    # - thread/stress_recurse.py is flaky
     file ./ports/unix/build-coverage/micropython
-    (cd tests && MICROPY_MICROPYTHON=../ports/unix/build-coverage/micropython ./run-tests.py --exclude 'vfs_posix.*\.py')
+    (cd tests && MICROPY_MICROPYTHON=../ports/unix/build-coverage/micropython MICROPY_TEST_TIMEOUT=90 ./run-tests.py --exclude 'vfs_posix.*\.py|thread/stress_recurse.py')
 }
 
 function ci_unix_qemu_riscv64_setup {
@@ -837,8 +844,11 @@ function ci_unix_qemu_riscv64_build {
 }
 
 function ci_unix_qemu_riscv64_run_tests {
+    # Issues with RISCV-64 tests:
+    # - thread/stress_aes.py takes around 140 seconds
+    # - thread/stress_recurse.py is flaky
     file ./ports/unix/build-coverage/micropython
-    (cd tests && MICROPY_MICROPYTHON=../ports/unix/build-coverage/micropython ./run-tests.py)
+    (cd tests && MICROPY_MICROPYTHON=../ports/unix/build-coverage/micropython MICROPY_TEST_TIMEOUT=180 ./run-tests.py --exclude 'thread/stress_recurse.py')
 }
 
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