1. counter performance (virtual users) in the thread.
If you check with each user a separate tracking counter, then the counter remains at 1.
If not checked then the counter will accumulate.
We see this counter will accumulate to 3.
2. counter performance in the loop
1. Select an independent manner for each user
index is from 1 to 3.
2. Without checked
We can see that this index is from 1 to the 9.