Killing Fork()

[toricred]

I have an import with a fork() in the AfterMenuLoad area. When the menu is closed (in this case the MediaPlayer OSD) does the fork() automatically get killed or do I need to do it manually? If it's not getting killed is it possible it would cause a memory leak?

[PLUCKYHD]

Does the fork have a loop under it where it keeps looping? Or does it end? It is me understanding the fork simply allows a process to run in the background and allow other code/process to run in the foreground
Of course I could misunderstand but I know the fork will end once the code below is executed unless is loops somewhere

[toricred]

Currently there is code under it to update a panel on the OSD every minute to show the time. It doesn't have anything built-in to end it, because I was hoping that when the OSD menu was ended by ending a show it would just go away. Now I'm beginning to think I need a way to end the fork manually if the OSD is closing.

[Opus4]

A forked thread won't end automatically, especially if is in a loop, so you'll need to add some sort of check to determine whether to keep it going, or let it end. The defaul STV does quite a few forked loops in AfterMenuLoad hooks, so you could check some of them out if you need ideas about how to have it end when the menu exits.

- Andy

[toricred]

How about a panel widget? Does it get killed when the OSD is killed? If so, I could just check to see if it still exists.

[toricred]

I decided to use HasMediaFile(), but I don't know how to be sure it worked. I can't tell that the fork has died in any way I can think of.

[GKusnick]

Basically the structure of your code should be something like this:

Fork()
  ...initialize...
  If KeepLooping()
    ...do something...
    If KeepLooping()
  ...cleanup...

where the KeepLooping() function decides whether the thread should terminate or continue running. This needn't be a function; you could for instance just check an attribute variable instead, and put code in BeforeMenuUnload to set the variable to some value that tells the forked thread to quit.

To make sure it's working right, put some calls to DebugLog() in the initialize, loop body, and cleanup sections of the code so you can see the control flow.

Keeping a handle on the Panel widget won't tell you when it's been freed, since it won't be freed as long as you have a handle on it. BeforeMenuUnload is your signal that the menu is being unloaded, and it's up to you to propagate that signal to any forked threads you've created.

[PLUCKYHD]

Originally Posted by toricred

I decided to use HasMediaFile(), but I don't know how to be sure it worked. I can't tell that the fork has died in any way I can think of.

Put a false and debug log it. If you see your message in the log then it is killed.

If HasMediaFile()

true
run your refresh or whatever you are doing

false

DebugLog("Message")

[PLUCKYHD]

Originally Posted by GKusnick

propagate that signal to any forked threads you've created.

Man this was not there when I posted above

[toricred]

It turns out that the MC MediaPlayer Menu already has a variable being set in the BeforeMenuUnload area named forkstop. I just used that. I haven't done anything with the debugging yet, but I'll work on it later this week.