How to generate dynamic file name by using pipeline execute

We’re using pipeline execute to run the tasks in parallel by check Reuse executions to process documents and changed Pool Size. But in the pipeline execute called pipeline, it will generate a log file as an output. How do we generate different file names for different pipeline executions?
We tried to use date.now() in the log file, but sometimes it will generate the same file name, like if we set the pool size to 40, it will provide 39 files only, one file will be overwritten. Is there a way we can add the pipeline execute sequence something like that?