Second app instance does not exit

[Junology]

Most appropriate sub-area of Processing 4?

PDE

Processing version

4.4.3 (portable)

Operating system

Linux (Ubuntu 20.04 x64)

Steps to reproduce this

"1. Download processing-4.4.3-linux-x64-portable.zip, extract it, and cd Processing/bin

2. ./Processing & and wait for Processing to launch.

3. ./Processing & again and wait for the second Processing IDE to launch.

4. Close both Processing windows.

5. ps | grep Processing and you'll see the second Processing process is still alive."

snippet

Additional context

I also observed the same happens for local build with Gradle.
The problem is not critical since Ctrl-C terminates it anyway, but it is a bit bothering when it happens.

Would you like to work on the issue?

No; I am not familier with Kotlin, sorry.

[Stefterv]

Good point, I've also seen this happen on macOS. As for a bit of background:

processing4/app/src/processing/app/SingleInstance.java

Lines 52 to 54 in c83f44c

	static boolean alreadyRunning(String[] args) {
	return Preferences.get(SERVER_PORT) != null && sendArguments(args);
	}

I suspect something in the send arguments code might not be finishing, keeping the second instance of Processing alive.

[Junology]

Glancing at the source, I noticed that existing instance check, i.e., SingleInstance.alreadyRunning is performed in processing.app.Base. IMO, the method should be called from the genuine startup code processing.app.ui.Start.main, right? Otherwise, we have to see the splash screen in each time we open a sketch from file managers, as it is now.

[AhmedMagedC]

I can also reproduce this bug on windows
I have also observed that when you open multiple instances like three processes and you try to close any of them, they all remain exist, until you close every one of them then only one of the processes exits and the rest remains

i would love to work on this issue