Add a timeout when resolving an object's properties.

_pydevd_bundle/pydevd_constants.py

@@ -370,6 +370,10 @@ def as_int_in_env(env_key, default):
 # on how the thread interruption works (there are some caveats related to it).
 PYDEVD_INTERRUPT_THREAD_TIMEOUT = as_float_in_env("PYDEVD_INTERRUPT_THREAD_TIMEOUT", -1)
 
+# Timeout used to prevent class properties from resolving too slowly
+# A value <= 0 means this is disabled.
+PYDEVD_PROPERTY_RESOLVE_TIMEOUT = as_float_in_env("PYDEVD_PROPERTY_RESOLVE_TIMEOUT", 1.0)
+
 # If PYDEVD_APPLY_PATCHING_TO_HIDE_PYDEVD_THREADS is set to False, the patching to hide pydevd threads won't be applied.
 PYDEVD_APPLY_PATCHING_TO_HIDE_PYDEVD_THREADS = (
     os.getenv("PYDEVD_APPLY_PATCHING_TO_HIDE_PYDEVD_THREADS", "true").lower() in ENV_TRUE_LOWER_VALUES

_pydevd_bundle/pydevd_resolver.py

@@ -12,8 +12,10 @@
     DebugInfoHolder,
     IS_PYPY,
     GENERATED_LEN_ATTR_NAME,
+    get_global_debugger,
 )
 from _pydevd_bundle.pydevd_safe_repr import SafeRepr
+from _pydevd_bundle.pydevd_timeout import create_interrupt_this_thread_callback
 from _pydevd_bundle import pydevd_constants
 
 TOO_LARGE_MSG = "Maximum number of items (%s) reached. To show more items customize the value of the PYDEVD_CONTAINER_RANDOM_ACCESS_MAX_ITEMS environment variable."
@@ -184,12 +186,32 @@ def _get_py_dictionary(self, var, names=None, used___dict__=False):
         timer = Timer()
         cls = type(var)
         for name in names:
+            name_as_str = name
             try:
-                name_as_str = name
                 if name_as_str.__class__ != str:
                     name_as_str = "%r" % (name_as_str,)
 
-                if not used___dict__:
+                class_attr_type = None
+                if hasattr(var.__class__, name_as_str):
+                    class_attr = getattr(var.__class__, name)
+                    class_attr_type = type(class_attr)
+
+                timeout_sec = pydevd_constants.PYDEVD_PROPERTY_RESOLVE_TIMEOUT
+                if (
+                    class_attr_type is property
+                    and timeout_sec > 0
+                    and (py_db := get_global_debugger())
+                ):
+                    try:
+                        on_interrupt_timeout = create_interrupt_this_thread_callback()
+                        timeout_tracker = py_db.timeout_tracker
+                        with timeout_tracker.call_on_timeout(
+                            timeout_sec, on_interrupt_timeout
+                        ):
+                            attr = getattr(var, name)
+                    except KeyboardInterrupt:
+                        attr = f"Timeout resolving {class_attr_type.__name__} attribute: {name}"
+                elif not used___dict__:
                     attr = getattr(var, name)
                 else:
                     attr = var.__dict__[name]

tests_python/test_resolvers.py

@@ -1,9 +1,10 @@
 from _pydevd_bundle.pydevd_constants import IS_PY36_OR_GREATER, GENERATED_LEN_ATTR_NAME
 from _pydevd_bundle import pydevd_constants, pydevd_frame_utils
+from pydevd import PyDB
+from time import sleep
 import pytest
 import sys
 
-
 def check_len_entry(len_entry, first_2_params):
     assert len_entry[:2] == first_2_params
     assert callable(len_entry[2])
@@ -124,6 +125,42 @@ def __init__(self):
     assert contents_debug_adapter_protocol == [("(1, 2)", (3, 4), ".__dict__[(1, 2)]")]
 
 
+def test_object_resolver_slow_property():
+    from _pydevd_bundle.pydevd_resolver import DefaultResolver
+
+    default_resolver = DefaultResolver()
+
+    class MyObject(object):
+        def __init__(self):
+            self.a = 10
+            self.b = 20
+
+        @property
+        def c(self):
+            sleep(0.2)
+            return 30
+
+        @property
+        def d(self):
+            return 40
+
+    pydevd_constants.PYDEVD_PROPERTY_RESOLVE_TIMEOUT = 0.1
+    _py_db = PyDB()
+    obj = MyObject()
+    dictionary = clear_contents_dictionary(default_resolver.get_dictionary(obj))
+    assert dictionary == {"a": 10, "b": 20, "c": "Timeout resolving property attribute: c", "d": 40}
+
+    contents_debug_adapter_protocol = clear_contents_debug_adapter_protocol(
+        default_resolver.get_contents_debug_adapter_protocol(obj)
+    )
+    assert contents_debug_adapter_protocol == [
+        ("a", 10, ".a"),
+        ("b", 20, ".b"),
+        ("c", "Timeout resolving property attribute: c", ".c"),
+        ("d", 40, ".d"),
+    ]
+
+
 def test_django_forms_resolver():
     from _pydevd_bundle.pydevd_resolver import DjangoFormResolver