Remove comm hash and add per-comm caches (#724)

---------

Co-authored-by: David A. Ham <david.ham@imperial.ac.uk>
Co-authored-by: Connor Ward <c.ward20@imperial.ac.uk>

Author: 3 people

.github/workflows/ci.yml

@@ -17,7 +17,7 @@ jobs:
       # Don't immediately kill all if one Python version fails
       fail-fast: false
       matrix:
-        python-version: ['3.8', '3.9', '3.10', '3.11']
+        python-version: ['3.9', '3.10', '3.11', '3.12']
     env:
       CC: mpicc
       PETSC_DIR: ${{ github.workspace }}/petsc
@@ -58,15 +58,15 @@ jobs:
         working-directory: ${{ env.PETSC_DIR }}/src/binding/petsc4py
         run: |
           python -m pip install --upgrade pip
-          python -m pip install --upgrade wheel 'cython<3' numpy
+          python -m pip install --upgrade wheel cython numpy
           python -m pip install --no-deps .
 
       - name: Checkout PyOP2
         uses: actions/checkout@v2
         with:
           path: PyOP2
 
-      - name: Install PyOP2
+      - name: Install PyOP2 dependencies
         shell: bash
         working-directory: PyOP2
         run: |
@@ -76,7 +76,21 @@ jobs:
           python -m pip install pulp
           python -m pip install -U flake8
           python -m pip install -U pytest-timeout
-          python -m pip install .
+
+      - name: Install PyOP2 (Python <3.12)
+        if: ${{ matrix.python-version != '3.12' }}
+        shell: bash
+        working-directory: PyOP2
+        run: python -m pip install .
+
+        # Not sure if this is a bug in setuptools or something PyOP2 is doing wrong
+      - name: Install PyOP2 (Python == 3.12)
+        if: ${{ matrix.python-version == '3.12' }}
+        shell: bash
+        working-directory: PyOP2
+        run: |
+          python -m pip install -U setuptools
+          python setup.py install
 
       - name: Run linting
         shell: bash
@@ -86,7 +100,10 @@ jobs:
       - name: Run tests
         shell: bash
         working-directory: PyOP2
-        run: pytest --tb=native --timeout=480 --timeout-method=thread -o faulthandler_timeout=540 -v test
+        run: |
+          # Running parallel test cases separately works around a bug in pytest-mpi
+          pytest -k "not parallel" --tb=native --timeout=480 --timeout-method=thread -o faulthandler_timeout=540 -v test
+          mpiexec -n 3 pytest -k "parallel[3]" --tb=native --timeout=480 --timeout-method=thread -o faulthandler_timeout=540 -v test
         timeout-minutes: 10
 
       - name: Build documentation