1 inc_counter
(): count = 1, unlocking mutex
2 inc_counter
(): count = 2, unlocking mutex
3 inc_counter
(): count = 3, unlocking mutex
4 inc_counter
(): count = 4, unlocking mutex
5 inc_counter
(): count = 5, unlocking mutex
6 inc_counter
(): count = 6, unlocking mutex
7 inc_counter
(): count = 7, unlocking mutex
8 inc_counter
(): count = 8, unlocking mutex
9 inc_counter
(): count = 9, unlocking mutex
10 inc_counter
(): count = 10, unlocking mutex
11 inc_counter
(): count = 11, unlocking mutex
12 inc_counter
(): count = 12, unlocking mutex
14 inc_counter
(): count = 13, unlocking mutex
15 inc_counter
(): count = 14, unlocking mutex
16 inc_counter
(): count = 15, unlocking mutex
17 inc_counter
(): count = 16, unlocking mutex
18 inc_counter
(): count = 17, unlocking mutex
19 inc_counter
(): count = 18, unlocking mutex
20 inc_counter
(): count = 19, unlocking mutex
21 inc_counter
(): count = 20, unlocking mutex
