From 7c7ef60b73ae8213723a7cb08d7b682d41baf71c Mon Sep 17 00:00:00 2001
From: Pragyaan Gaur <pragyaangaur12@gmail.com>
Date: Wed, 12 Aug 2026 13:09:52 +0530
Subject: [PATCH] Fix broken append and var_names paths in SU2.io.data

save_data(append=True) called load(), which does not exist; the function
was renamed to load_data() and this call site was missed. Calling
load_data() directly is not sufficient because filelock is not reentrant
and save_data already holds the lock, so the read body is extracted into
a private _read_data() helper used by both.

load_data(var_names=...) deleted from the dictionary while iterating
.keys(), which raises RuntimeError on Python 3.
---
 SU2_PY/SU2/io/data.py | 94 ++++++++++++++++++++++++-------------------
 1 file changed, 52 insertions(+), 42 deletions(-)

diff --git a/SU2_PY/SU2/io/data.py b/SU2_PY/SU2/io/data.py
index a2265c11984..810e901786e 100644
--- a/SU2_PY/SU2/io/data.py
+++ b/SU2_PY/SU2/io/data.py
@@ -67,13 +67,6 @@ def load_data(file_name, var_names=None, file_format="infer", core_name="python_
     ('.mat','.pkl')
     """
 
-    try:
-        import scipy.io
-
-        scipy_loaded = True
-    except ImportError:
-        scipy_loaded = False
-
     if not os.path.exists(file_name):
         raise Exception("File does not exist: %s" % file_name)
 
@@ -87,31 +80,7 @@ def load_data(file_name, var_names=None, file_format="infer", core_name="python_
 
     # get filelock
     with filelock(file_name):
-
-        # LOAD MATLAB
-        if file_format == "matlab" and scipy_loaded:
-            input_data = scipy.io.loadmat(
-                file_name=file_name,
-                squeeze_me=False,
-                chars_as_strings=True,
-                struct_as_record=True,
-            )
-            # pull core variable
-            assert core_name in input_data, "core data not found"
-            input_data = input_data[core_name]
-
-            # convert recarray to dictionary
-            input_data = rec2dict(input_data)
-
-        # LOAD PICKLE
-        elif file_format == "pickle":
-            input_data = load_pickle(file_name)
-            # pull core variable
-            assert core_name in input_data, "core data not found"
-            input_data = input_data[core_name]
-
-        #: if file_format
-
+        input_data = _read_data(file_name, file_format, core_name)
     #: with filelock
 
     # load specified varname into dictionary
@@ -121,7 +90,8 @@ def load_data(file_name, var_names=None, file_format="infer", core_name="python_
             var_names = [
                 var_names,
             ]
-        for key in input_data.keys():
+        # iterate a copy of the keys, the dictionary is modified in the loop
+        for key in list(input_data.keys()):
             if not key in var_names:
                 del input_data[key]
         #: for key
@@ -130,14 +100,59 @@ def load_data(file_name, var_names=None, file_format="infer", core_name="python_
     return input_data
 
 
-#: def load()
+#: def load_data()
 
 
 # -------------------------------------------------------------------
-#  Save a Dictionary of Data
+#  Read a Dictionary of Data, without locking
 # -------------------------------------------------------------------
 
 
+def _read_data(file_name, file_format, core_name):
+    """data = _read_data( file_name, file_format, core_name )
+
+    Reads the data dictionary from file, assuming the caller already
+    holds the filelock for file_name. filelock is not reentrant, so
+    this must never acquire the lock itself.
+    """
+
+    try:
+        import scipy.io
+
+        scipy_loaded = True
+    except ImportError:
+        scipy_loaded = False
+
+    # LOAD MATLAB
+    if file_format == "matlab" and scipy_loaded:
+        input_data = scipy.io.loadmat(
+            file_name=file_name,
+            squeeze_me=False,
+            chars_as_strings=True,
+            struct_as_record=True,
+        )
+        # pull core variable
+        assert core_name in input_data, "core data not found"
+        input_data = input_data[core_name]
+
+        # convert recarray to dictionary
+        input_data = rec2dict(input_data)
+
+    # LOAD PICKLE
+    elif file_format == "pickle":
+        input_data = load_pickle(file_name)
+        # pull core variable
+        assert core_name in input_data, "core data not found"
+        input_data = input_data[core_name]
+
+    #: if file_format
+
+    return input_data
+
+
+#: def _read_data()
+
+
 def save_data(
     file_name, data_dict, append=False, file_format="infer", core_name="python_data"
 ):
@@ -189,12 +204,7 @@ def save_data(
             if not os.path.exists(file_name):
                 raise Exception("Cannot append, file does not exist: %s" % file_name)
             # load old data
-            data_dict_old = load(
-                file_name=file_name,
-                var_names=None,
-                file_format=file_format,
-                core_name=core_name,
-            )
+            data_dict_old = _read_data(file_name, file_format, core_name)
             # check for keys not in new data
             for key, value in data_dict_old.items():
                 if not (key in data_dict):
@@ -227,7 +237,7 @@ def save_data(
     return
 
 
-#: def save()
+#: def save_data()
 
 
 # -------------------------------------------------------------------