Try setting JAVA_STARTED_ON_FIRST_THREAD_pid environment variable on macOS

[ctrueden]

The node-java project, which allows to embed Java and wrap its classes from inside a node.js app, has an analogous problem with AWT on macOS. The relevant issue is joeferner/node-java#21. But there is a comment saying you can set an environment variable JAVA_STARTED_ON_FIRST_THREAD_pid=1 where pid is the process ID of the parent process, and then everything magically works. Let's try it!

[ctrueden]

I tested this by commenting out the if macos and mode == Mode.INTERACTIVE prohibition in imagej.init, and then doing:

import os
os.environ['JAVA_STARTED_ON_FIRST_THREAD_pid'] = str(os.getpid())
ij = imagej.init(mode='interactive')
ij.ui().showUI()

It almost works! There is just one problem: the GUI never actually appears. But it doesn't hang. Java is working under the hood, including the AWT subsystem.

That's all I have time for now, but it might be progress.

[ctrueden]

Relatedly, there is a flag you can pass to Java directly,-XstartOnFirstThread, which might be the same thing. Need to try it.