Merge pull request #318 from imagej/detach-init-thread

Detach initialization QThread after ImageJ initialized

.github/workflows/build.yml

@@ -18,12 +18,12 @@ env:
 
 jobs:
   test-pip:
-    name: ${{ matrix.platform }} py${{ matrix.python-version }}
+    name: ${{ matrix.platform }} (python ${{ matrix.python-version }})
     runs-on: ${{ matrix.platform }}
     strategy:
       matrix:
         platform: [ubuntu-latest, windows-latest, macos-latest]
-        python-version: ['3.8', '3.12']
+        python-version: ['3.9', '3.12']
 
     steps:
       - uses: actions/checkout@v2

dev-environment.yml

@@ -18,7 +18,7 @@ name: napari-imagej-dev
 channels:
   - conda-forge
 dependencies:
-  - python >= 3.8, < 3.13
+  - python >= 3.9, < 3.13
   # Project dependencies
   - confuse >= 2.0.0
   - imglyb >= 2.1.0

environment.yml

@@ -18,7 +18,7 @@ name: napari-imagej
 channels:
   - conda-forge
 dependencies:
-  - python >= 3.8, < 3.13
+  - python >= 3.9, < 3.13
   # Project depenencies
   - confuse >= 2.0.0
   - imglyb >= 2.1.0

pyproject.toml

@@ -16,10 +16,10 @@ classifiers = [
     "Intended Audience :: Science/Research",
     "Framework :: napari",
     "Programming Language :: Python :: 3 :: Only",
-    "Programming Language :: Python :: 3.8",
     "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
+    "Programming Language :: Python :: 3.12",
     "Operating System :: Microsoft :: Windows",
     "Operating System :: Unix",
     "Operating System :: MacOS",
@@ -32,7 +32,7 @@ classifiers = [
 ]
 
 # NB: Keep this in sync with environment.yml AND dev-environment.yml!
-requires-python = ">=3.8, <3.13"
+requires-python = ">=3.9, <3.13"
 dependencies = [
     "confuse >= 2.0.0",
     "imglyb >= 2.1.0",

src/napari_imagej/java.py

@@ -310,6 +310,10 @@ def HashMap(self):
     def Path(self):
         return "java.nio.file.Path"
 
+    @JavaClasses.java_import
+    def Thread(self):
+        return "java.lang.Thread"
+
     @JavaClasses.java_import
     def Window(self):
         return "java.awt.Window"

src/napari_imagej/widgets/napari_imagej.py

@@ -16,7 +16,7 @@
 from napari.layers import Layer
 from qtpy.QtCore import QModelIndex, QThread, Signal, Slot
 from qtpy.QtWidgets import QVBoxLayout, QWidget
-from scyjava import jstacktrace, when_jvm_stops
+from scyjava import jstacktrace, when_jvm_stops, jvm_started
 
 from napari_imagej import nij
 from napari_imagej.java import jc
@@ -248,10 +248,17 @@ def run(self):
             self._finalize_info_bar()
             # Finalize EventSubscribers
             self._finalize_subscribers()
+            # jc.Thread.detach()
         except Exception as e:
             # Handle the exception on the GUI thread
             self.widget.ij_error_handler.emit(e)
             return
+        finally:
+            # Detach JPype thread
+            # NB Java must NOT be touched on this thread after this call. See
+            # https://jpype.readthedocs.io/en/v1.5.0/userguide.html#python-threads
+            if jvm_started() and jc.Thread.isAttached():
+                jc.Thread.detach()
 
     def _finalize_results_tree(self):
         """