From f400f30fc3f7d5aec09c4ebb8875c53e3344c91d Mon Sep 17 00:00:00 2001
From: Douglas Raillard <douglas.raillard@arm.com>
Date: Wed, 17 Nov 2021 15:01:16 +0000
Subject: [PATCH 1/3] exekall: Remove dead variable

---
 tools/exekall/exekall/_utils.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/tools/exekall/exekall/_utils.py b/tools/exekall/exekall/_utils.py
index dcb6e8967..c6ecbc03c 100644
--- a/tools/exekall/exekall/_utils.py
+++ b/tools/exekall/exekall/_utils.py
@@ -319,7 +319,6 @@ def is_serializable(obj, raise_excep=False):
     """
     Try to Pickle the object to see if that raises any exception.
     """
-    stream = io.StringIO()
     try:
         # This may be slow for big objects but it is the only way to be sure
         # it can actually be serialized
-- 
GitLab


From 47dc9f8b945755168654a75d093fd1765c7c11a2 Mon Sep 17 00:00:00 2001
From: Douglas Raillard <douglas.raillard@arm.com>
Date: Wed, 17 Nov 2021 16:51:04 +0000
Subject: [PATCH 2/3] exekall._utils: Fix ExceptionPickler memory leak

FIX

Workaround the memory leak described by:
https://bugs.python.org/issue45830
---
 tools/exekall/exekall/_utils.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/exekall/exekall/_utils.py b/tools/exekall/exekall/_utils.py
index c6ecbc03c..e49879c80 100644
--- a/tools/exekall/exekall/_utils.py
+++ b/tools/exekall/exekall/_utils.py
@@ -253,8 +253,12 @@ class ExceptionPickler(pickle.Pickler):
                 raise KeyError
 
     def __init__(self, *args, **kwargs):
-        self.dispatch_table = self._DispatchTable(self)
+
+        # Due to this issue, it is critical that "dispatch_table" is set after
+        # calling super().__init__
+        # https://bugs.python.org/issue45830
         super().__init__(*args, **kwargs)
+        self.dispatch_table = self._DispatchTable(self)
 
     @staticmethod
     def _make_excep(excep_cls, dct):
-- 
GitLab


From f3e94d243b9759437d52bc5c364c47f974d67358 Mon Sep 17 00:00:00 2001
From: Douglas Raillard <douglas.raillard@arm.com>
Date: Wed, 17 Nov 2021 16:51:52 +0000
Subject: [PATCH 3/3] exekall._utils: Reduce peak memory consumption of
 is_serializable

Pickle into a fake file that discards data rather than building up a
bytestring in memory.
---
 tools/exekall/exekall/_utils.py | 40 +++++++++++++++++++--------------
 1 file changed, 23 insertions(+), 17 deletions(-)

diff --git a/tools/exekall/exekall/_utils.py b/tools/exekall/exekall/_utils.py
index e49879c80..a805f087e 100644
--- a/tools/exekall/exekall/_utils.py
+++ b/tools/exekall/exekall/_utils.py
@@ -318,24 +318,30 @@ class ExceptionPickler(pickle.Pickler):
         pickler = cls(f, **kwargs)
         return pickler.dump(obj)
 
+    @classmethod
+    def is_serializable(cls, obj, raise_excep=False):
+        """
+        Try to Pickle the object to see if that raises any exception.
+        """
+        class DevNull:
+            def write(self, _):
+                pass
+        try:
+            # This may be slow for big objects but it is the only way to be
+            # sure it can actually be serialized
+            cls.dump_file(DevNull(), obj)
+        except (TypeError, pickle.PickleError, AttributeError) as e:
+            debug('Cannot serialize instance of {}: {}'.format(
+                type(obj).__qualname__, str(e)
+            ))
+            if raise_excep:
+                raise NotSerializableError(obj) from e
+            return False
+        else:
+            return True
 
-def is_serializable(obj, raise_excep=False):
-    """
-    Try to Pickle the object to see if that raises any exception.
-    """
-    try:
-        # This may be slow for big objects but it is the only way to be sure
-        # it can actually be serialized
-        ExceptionPickler.dump_bytestring(obj)
-    except (TypeError, pickle.PickleError, AttributeError) as e:
-        debug('Cannot serialize instance of {}: {}'.format(
-            type(obj).__qualname__, str(e)
-        ))
-        if raise_excep:
-            raise NotSerializableError(obj) from e
-        return False
-    else:
-        return True
+
+is_serializable = ExceptionPickler.is_serializable
 
 
 def once(callable_):
-- 
GitLab