Semaphores - comments

• Intuitively easy to use.

• wait() and signal() are to be implemented as atomic operations.

• Difficulties:

  • signal() and wait() may be exchanged inadvertently by the programmer. This may result in deadlock or violation of mutual exclusion.
  • signal() and wait() may be left out.

• Related wait() and signal() may be scattered all over the code among the processes.

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