Software Solution 3 (Peterson’s)

• Only two processes.

• Local process is i, other is j.

• Mutual exclusion - good.

• Progress - good.

• Bounded time - good.

Shared turn: (0..1)=0;

Shared flag: array [0..1] of boolean=[false, false];

.

Repeat

flag[ i ] := true; turn := j;

while (flag[ j ] and turn=j) do no-op;

critical section

flag[ i ] := false;

remainder section

Forever

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