More tests for concurrency info

test/container_test.py

@@ -2463,3 +2463,21 @@ def test_container_app_one_matching(servicer, event_loop):
 def test_no_event_loop(servicer, event_loop):
     ret = _run_container(servicer, "test.supports.functions", "get_running_loop")
     assert _unwrap_exception(ret) == "RuntimeError('no running event loop')"
+
+
+@skip_github_non_linux
+def test_is_main_thread_sync(servicer, event_loop):
+    ret = _run_container(servicer, "test.supports.functions", "is_main_thread_sync")
+    assert _unwrap_scalar(ret) is True
+
+
+@skip_github_non_linux
+def test_is_main_thread_async(servicer, event_loop):
+    ret = _run_container(servicer, "test.supports.functions", "is_main_thread_async")
+    assert _unwrap_scalar(ret) is True
+
+
+@skip_github_non_linux
+def test_import_thread_is_main_thread(servicer, event_loop):
+    ret = _run_container(servicer, "test.supports.functions", "import_thread_is_main_thread")
+    assert _unwrap_scalar(ret) is True

test/supports/functions.py

@@ -1,6 +1,7 @@
 # Copyright Modal Labs 2022
 import asyncio
 import contextlib
+import threading
 import time
 
 from modal import (
@@ -718,3 +719,21 @@ def check_container_app():
 @app.function()
 def get_running_loop(x):
     return asyncio.get_running_loop()
+
+
+@app.function()
+def is_main_thread_sync(x):
+    return threading.main_thread() == threading.current_thread()
+
+
+@app.function()
+async def is_main_thread_async(x):
+    return threading.main_thread() == threading.current_thread()
+
+
+_import_thread_is_main_thread = threading.main_thread() == threading.current_thread()
+
+
+@app.function()
+def import_thread_is_main_thread(x):
+    return _import_thread_is_main_thread