Sometimes when I double click on a patch to run it on Windows, it starts a second instance of Pure Data 0.56.0. Pd opens a second console window, and all messages from the second patch go to the second console window. Why does this only happen some times? Is there a way to make it happen all the time? Do different instances run in different threads? When I get a second instance of Pure Data, it is unable to connect to my MIDI device. Are there other restrictions on multiple instances of Pure Data?

I've been looking at using [Pd~] to run different patches in different threads, but it would be easier to run each patch in a different instance of Pure Data, if there's a way to consistently start multiple instances.

I don't remember seeing this before 0.56.0. Is it a new feature?

@jamcultur Strange behaviour.
Yes, you can start a second instance. A batch file will do that.....

start "C:\Program Files (x86)\pd\bin\pd.com" start C:\Users\"David"\Desktop\PDMusic\minx\minx_run.pd
start "C:\Program Files (x86)\pd\bin\pd.com" start C:\Users\"David"\Desktop\PDMusic\minx\minx_run.pd
exit

Change the path to your Pd location. Pd.com or Pd.exe shouldn't matter.
The above code will open the same patch twice in different instances. You can open 2 different patches of course.

Windows assigns processes to threads automatically.... different threads I am pretty sure. There might be a way to ensure that but you would need to copy the Pd binary and and rename the copy probably.

A second instance will start with different sockets (Pd<>Wish)so they will be completely separate.
When Pd opens it will have exclusive access to midi and audio pins set in its settings... so the second instance will not get access. You will have to use [netsend] to transfer data between them.

I have tried using command line flags to set each instance to use different devices... no luck so far.
You would have to set audio and midi for the second instance after opening.
David.

@whale-av Thanks for the info! I'll try using a bat file to run multiple patches. My main patch does all the audio and MIDI I/O, so I think it should work as along as I start the main patch first.

Since the current behavior is inconsistent, I'm wondering if I should open an issue on GitHub. Maybe it's a bug.

@whale-av The bat file does open the patch, but it doesn't open a new console window like I saw previously, and I only see one pd in the Windows Task Manager. Also, the patch is able to access audio and MIDI without changing the settings. Do you know if there is a way to verify whether Windows is running the patch in a different thread?

Press control+shift+escape to open the task manager, in details you can right click on wish86.exe and or pd.exe and define the allowed cores for the application.
I never tryed this but just saw it there now.
As @whale-av said, maybe you have to copy the pd folder and maybe rename the second application.
I guess there are other ways to start and run applications on a specific thread in win, but you can search for yourself as this is not Pd specific.

And as @whale-av said, these instances are completly independent and they
won't run in sync. They run asynchronous. Useful for special tasks, for example to do sth with fast-forward-message while the other patch stays in real-time.

If you want to spread patches across different cpu cores but still in sync, use the [pd~] object.

Either way shmem lib is very useful to share memory / share arrays between pd-instances.

(Looking at the task-manager when using [pd~] I see the cores are constanly changing, Looks like Windows is dynamicly changing the cores. Might be good enough or even better to let Windows manage it instead of assigning fixed threads. Same might be true when running asynchronous instances. )

@jamcultur Batch files....
Tricky.
A path with spaces must be contained within inverted commas ""
Putting inverted commas around the executable name e.g. "pd.exe" opens the installed program and not the one that the path has been set to.

I have finally managed to set flags for each instance....... twice.zip
The second.bat can be included in pd_twice.bat but I am finding it easier to keep them separate for now for testing.

It seems that trying to set midi device numbers in the second instance stymied my previous efforts.

But here that is fixed and working..... pd-twice.zip

Flags here....... http://msp.ucsd.edu/Pd_documentation/resources/chapter3.htm#s3.4.1
..... so each instance could use a different audio or midi device determined in the batch file...
David.