Address GC with JPype ≥1.5.0

.github/workflows/pytest.yaml

@@ -28,8 +28,8 @@ jobs:
         - "3.8"  # Earliest version supported by ixmp
         - "3.9"
         - "3.10"
-        - "3.11" # Latest supported by ixmp
-        # - "3.12"  # Pending JPype support; see iiasa/ixmp#501
+        - "3.11"
+        - "3.12"  # Latest supported by ixmp
 
         # commented: force a specific version of pandas, for e.g. pre-release
         # testing
@@ -92,10 +92,6 @@ jobs:
       run: echo "RETICULATE_PYTHON=$pythonLocation" >> $GITHUB_ENV
       shell: bash
 
-    - name: Work around https://bugs.launchpad.net/lxml/+bug/2035206
-      if: matrix.python-version == '3.8' && matrix.os == 'macos-latest'
-      run: pip install "lxml == 4.9.2"
-
     - name: Install Python package and dependencies
       # [docs] contains [tests], which contains [report,tutorial]
       run: |
@@ -104,10 +100,6 @@ jobs:
         # commented: use with "pandas-version" in the matrix, above
         # pip install --upgrade pandas${{ matrix.pandas-version }}
 
-    - name: TEMPORARY Work around iiasa/ixmp#463
-      if: matrix.python-version != '3.11'
-      run: pip install "JPype1 != 1.4.1"
-
     - name: Install R dependencies and tutorial requirements
       run: |
         install.packages(c("remotes", "Rcpp"))
@@ -125,7 +117,13 @@ jobs:
       shell: Rscript {0}
 
     - name: Run test suite using pytest
-      run: pytest ixmp -m "not performance" --verbose -rA --cov-report=xml --color=yes
+      run: |
+        pytest ixmp \
+          -m "not performance" \
+          --color=yes -rA --verbose \
+          --cov-report=xml \
+          --numprocesses=auto
+      shell: bash
 
     - name: Upload test coverage to Codecov.io
       uses: codecov/codecov-action@v3

RELEASE_NOTES.rst

@@ -14,7 +14,8 @@ Code that imports from the old locations will continue to work, but will raise :
 All changes
 -----------
 
-- Support for Python 3.7 is dropped (:pull:`492`).
+- :mod:`ixmp` is tested and compatible with `Python 3.12 <https://www.python.org/downloads/release/python-3120/>`__ (:pull:`504`).
+- Support for Python 3.7 is dropped (:pull:`492`), as it has reached end-of-life.
 - Rename :mod:`ixmp.report` and :mod:`ixmp.util` (:pull:`500`).
 - New reporting operators :func:`.from_url`, :func:`.get_ts`, and :func:`.remove_ts` (:pull:`500`).
 - New CLI command :program:`ixmp platform copy` and :doc:`CLI documentation <cli>` (:pull:`500`).
@@ -28,6 +29,9 @@ All changes
   - When a :class:`.GAMSModel` is solved with an LP status of 5 (optimal, but with infeasibilities after unscaling), :class:`.JDBCBackend` would attempt to read the output GDX file and fail, leading to an uninformative error message (:issue:`98`).
     Now :class:`.ModelError` is raised describing the situation.
 - Improved type hinting for static typing of code that uses :mod:`ixmp` (:issue:`465`, :pull:`500`).
+- :mod:`ixmp` requires JPype1 1.4.0 or earlier, for Python 3.10 and earlier (:pull:`504`).
+  With JPype1 1.4.1 and later, memory management in :class:`.CachingBackend` may not function as intended (:issue:`463`), which could lead to high memory use where many, large :class:`.Scenario` objects are created and used in a single Python program.
+  (For Python 3.11 and later, any version of JPype1 from the prior minimum (1.2.1) to the latest is supported.)
 
 .. _v3.7.0:
 

ixmp/backend/jdbc.py

@@ -127,8 +127,7 @@ def _raise_jexception(exc, msg="unhandled Java exception: "):
     """Convert Java/JPype exceptions to ordinary Python RuntimeError."""
     # Try to re-raise as a ValueError for bad model or scenario name
     arg = exc.args[0] if isinstance(exc.args[0], str) else ""
-    match = re.search(r"getting '([^']*)' in table '([^']*)'", arg)
-    if match:
+    if match := re.search(r"getting '([^']*)' in table '([^']*)'", arg):
         param = match.group(2).lower()
         if param in {"model", "scenario"}:
             raise ValueError(f"{param}={repr(match.group(1))}") from None
@@ -301,7 +300,7 @@ def __init__(self, jvmargs=None, **kwargs):
                 f"{e}\nCheck that dependencies of ixmp.jar are "
                 f"included in {Path(__file__).parents[2] / 'lib'}"
             )
-        except jpype.JException as e:  # pragma: no cover
+        except java.Exception as e:  # pragma: no cover
             # Handle Java exceptions
             jclass = e.__class__.__name__
             if jclass.endswith("HikariPool.PoolInitializationException"):
@@ -708,10 +707,18 @@ def get(self, ts):
         # either getTimeSeries or getScenario
         method = getattr(self.jobj, "get" + ts.__class__.__name__)
 
-        # Re-raise as a ValueError for bad model or scenario name, or other
-        with _handle_jexception():
+        # Re-raise as a ValueError for bad model or scenario name, or other with
+        # with _handle_jexception():
+        try:
             # Either the 2- or 3- argument form, depending on args
             jobj = method(*args)
+        except SystemError:
+            # JPype 1.5.0 with Python 3.12: "<built-in method __subclasscheck__ of
+            # _jpype._JClass object at …> returned a result with an exception set"
+            # At least transmute to a ValueError
+            raise ValueError("model, scenario, or version not found")
+        except BaseException as e:
+            _raise_jexception(e)
 
         self._index_and_set_attrs(jobj, ts)
 
@@ -938,7 +945,7 @@ def init_item(self, s, type, name, idx_sets, idx_names):
         # by Backend, so don't return here
         try:
             func(name, idx_sets, idx_names)
-        except jpype.JException as e:
+        except java.Exception as e:
             if "already exists" in e.args[0]:
                 raise ValueError(f"{repr(name)} already exists")
             else:

ixmp/core/scenario.py

@@ -574,7 +574,7 @@ def add_par(
                 # Multiple values
                 values = value
 
-            data = pd.DataFrame(zip(keys, values), columns=["key", "value"])
+            data = pd.DataFrame(zip_longest(keys, values), columns=["key", "value"])
             if data.isna().any(axis=None):
                 raise ValueError("Length mismatch between keys and values")
 

ixmp/tests/backend/test_base.py

@@ -1,3 +1,4 @@
+import sys
 from pathlib import Path
 
 import pytest
@@ -69,7 +70,9 @@ class BE2(Backend):
 def test_class():
     # An incomplete Backend subclass can't be instantiated
     with pytest.raises(
-        TypeError, match="Can't instantiate abstract class BE1 with abstract methods"
+        TypeError,
+        match="Can't instantiate abstract class BE1 with(out an implementation for)? "
+        "abstract methods",
     ):
         BE1()
 
@@ -145,6 +148,12 @@ def test_del_ts(self, test_mp):
         # Cache size has increased
         assert cache_size_pre + 1 == len(backend._cache)
 
+        # JPype ≥ 1.4.1 with Python ≤ 3.10 produces danging traceback/frame references
+        # to `s` that prevent it being GC'd at "del s" below. See
+        # https://github.com/iiasa/ixmp/issues/463 and test_jdbc.test_del_ts
+        if sys.version_info.minor <= 10:
+            s.__del__()  # Force deletion of cached objects associated with `s`
+
         # Delete the object; associated cache is freed
         del s
 

ixmp/tests/backend/test_jdbc.py

@@ -2,6 +2,7 @@
 import logging
 import os
 import platform
+import sys
 from sys import getrefcount
 from typing import Tuple
 
@@ -370,6 +371,12 @@ def test_verbose_exception(test_mp, exception_verbose_true):
     assert "at.ac.iiasa.ixmp.Platform.getScenario" in exc_msg
 
 
+@pytest.mark.xfail(
+    condition=sys.version_info.minor <= 10,
+    raises=AssertionError,
+    # See also test_base.TestCachingBackend.test_del_ts
+    reason="https://github.com/iiasa/ixmp/issues/463",
+)
 def test_del_ts():
     mp = ixmp.Platform(
         backend="jdbc",

ixmp/tests/core/test_scenario.py

@@ -1,4 +1,5 @@
 import re
+import sys
 
 import numpy.testing as npt
 import pandas as pd
@@ -93,10 +94,15 @@ def test_from_url(self, mp, caplog):
         with pytest.raises(Exception, match=expected):
             scen, mp = ixmp.Scenario.from_url(url + "#10000", errors="raise")
 
-        # Giving an invalid scenario with errors='warn' raises an exception
+        # Giving an invalid scenario with errors='warn' causes a message to be logged
         msg = (
-            "ValueError: scenario='Hitchhikerfoo'\n"
-            f"when loading Scenario from url: {repr(url + 'foo')}"
+            "ValueError: "
+            + (
+                "scenario='Hitchhikerfoo'"
+                if sys.version_info.minor != 12
+                else "model, scenario, or version not found"
+            )
+            + f"\nwhen loading Scenario from url: {repr(url + 'foo')}"
         )
         with assert_logs(caplog, msg):
             scen, mp = ixmp.Scenario.from_url(url + "foo")

ixmp/tests/test_cli.py

@@ -1,4 +1,5 @@
 import re
+import sys
 from pathlib import Path
 
 import pandas as pd
@@ -403,7 +404,12 @@ def test_solve(ixmp_cli, test_mp):
     ]
     result = ixmp_cli.invoke(cmd)
     assert result.exit_code == 1, result.output
-    assert "Error: model='non-existing'" in result.output
+    exp = (
+        "='non-existing'"
+        if sys.version_info.minor != 12
+        else ", scenario, or version not found"
+    )
+    assert f"Error: model{exp}" in result.output
 
     result = ixmp_cli.invoke([f"--url=ixmp://{test_mp.name}/foo/bar", "solve"])
     assert UsageError.exit_code == result.exit_code, result.output

ixmp/tests/test_model.py

@@ -16,7 +16,9 @@ class M1(Model):
         pass
 
     with pytest.raises(
-        TypeError, match="Can't instantiate abstract class M1 " "with abstract methods"
+        TypeError,
+        match="Can't instantiate abstract class M1 with(out an implementation for)? "
+        "abstract methods",
     ):
         M1()
 

ixmp/tests/test_util.py

@@ -92,17 +92,17 @@ def test_diff_data(test_mp):
     # Expected results
     exp_b = pd.DataFrame(
         [
-            ["chicago", 300.0, "cases", np.NaN, None, "left_only"],
-            ["new-york", np.NaN, None, 325.0, "cases", "right_only"],
+            ["chicago", 300.0, "cases", np.nan, np.nan, "left_only"],
+            ["new-york", np.nan, np.nan, 325.0, "cases", "right_only"],
             ["topeka", 275.0, "cases", 275.0, "cases", "both"],
         ],
         columns="j value_a unit_a value_b unit_b _merge".split(),
     )
     exp_d = pd.DataFrame(
         [
-            ["san-diego", "chicago", np.NaN, None, 1.8, "km", "right_only"],
-            ["san-diego", "new-york", np.NaN, None, 2.5, "km", "right_only"],
-            ["san-diego", "topeka", np.NaN, None, 1.4, "km", "right_only"],
+            ["san-diego", "chicago", np.nan, np.nan, 1.8, "km", "right_only"],
+            ["san-diego", "new-york", np.nan, np.nan, 2.5, "km", "right_only"],
+            ["san-diego", "topeka", np.nan, np.nan, 1.4, "km", "right_only"],
             ["seattle", "chicago", 1.7, "km", 123.4, "km", "both"],
             ["seattle", "new-york", 2.5, "km", 123.4, "km", "both"],
             ["seattle", "topeka", 1.8, "km", 123.4, "km", "both"],

pyproject.toml

@@ -24,6 +24,7 @@ classifiers = [
   "Programming Language :: Python :: 3.9",
   "Programming Language :: Python :: 3.10",
   "Programming Language :: Python :: 3.11",
+  "Programming Language :: Python :: 3.12",
   "Programming Language :: R",
   "Topic :: Scientific/Engineering",
   "Topic :: Scientific/Engineering :: Information Analysis",
@@ -33,6 +34,7 @@ dependencies = [
   "click",
   "genno >= 1.16",
   "JPype1 >= 1.2.1",
+  "JPype1 <= 1.4.0; python_version < '3.11'",
   "openpyxl",
   "pandas >= 1.2",
   "pint",
@@ -65,6 +67,7 @@ tests = [
   "pytest-benchmark",
   "pytest-cov",
   "pytest-rerunfailures",
+  "pytest-xdist",
 ]
 
 [project.scripts]
@@ -77,11 +80,6 @@ exclude_also = [
 ]
 omit = ["ixmp/util/sphinx_linkcode_github.py"]
 
-[tool.isort]
-profile = "black"
-
-[tool.mypy]
-
 [[tool.mypy.overrides]]
 # Packages/modules for which no type hints are available.
 module = [