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Asked: 2026-05-27T09:45:12+00:00

http://en.wikipedia.org/wiki/Lamport%27s_bakery_algorithm I have some problems to understand this algorithm. What happens if the current

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http://en.wikipedia.org/wiki/Lamport%27s_bakery_algorithm

I have some problems to understand this algorithm. What happens if the current thread and the thread, I am looking at the moment in the for loop are the same?

Threads: 0, 1, 2

Thread 1 takes ticket 1. Thread 2 takes ticket 2. Thread 0 does nothing.

Array = i: 0, 1, 2

Round 1:

  • Thread 1 (j=0): Array[0] = 0. next.
  • Thread 2 (j=0): Array[0] = 0. next.

Round 2:

  • Thread 1 (j=1): Array[1] = 1. (1,1) > (1,1)
  • Thread 2 (j=1): Array[1] = 1. (1,1) > (2,2)

(1,1) > (1,1) wrong.
(1,1) > (2,2) wrong.

Both threads are waiting…

What’s wrong? Is this a deadlock?

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1 Answer

  1. Editorial Team

    The while loop in the algorithm allows a thread to enter critical section when the inequality does not hold. It says: wait as long as the condition (Number[j] != 0) && ((Number[j], j) < (Number[i], i) is true.

    Since (1,1) is not greater than (1,1) the thread 1 can pass the loop and enter the critical section.

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