How to make threads work in a sync?

[DoctorStrange]

I have a file from which I take lines using the counter variable. The problem however is that even though I'm increasing the counter with +1 each time, all the threads work from the start of the file and do it as many times as there are threads.

For example, if I am using 10 threads, each line is being done 10 times. What can I do to avoid this and make threads work in a sync?

 

[zortexx]

Use Global Variable or text file to save counter value.