To identify exiftool's ppid

[BESTLyc]

Thanks for your useful tools. I create a exiftool's pool in my program, which is very useful in high concurrency scenarios. But when my program's proccess be killed in accident,the pool will lost control. So I want to manage them,so I want to get their pid and source program name, then when my program restart, it can check and close the previous exiftool's pool.