User Interface
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Introduction
Since the technology has been improving dramatically, the deadlock has been defined many times in many fields of computer science, such as in communication field, database field and operation system field. According to LevineÐŽ¦s article, there are five classes of dead states to define deadlock in computer science literature. However, these five classes does not define deadlock completely. In this essay, it would define deadlock in three different classes. They are: Communication deadlock, Scheduling Deadlock and Interleaved deadlock. In addition, these classes have defined by circular dead states and active and inactive dead states.
In operation system text, deadlock can be defined that when process request resources and the resources are not available to be used at that time, so the process is be waiting. However, the process is hold by other waiting processes. As a result, the waiting process could never change states.
Communication deadlock
The two processes could not be completed due to two processes are designed to execute to wait for a resource instance until they create a resource instance requested by the other. In other words, a dead lock occurs with a wrong process, which is waiting for a message before send an awaited message to each other. For example, a process outputs a wrong value and all processes can not accept this value to do next process in order to the value would discard and the service incomplete. Assuming a flawed resource, it can be coursed by defective coprocessor. Therefore, a process would be processing continually and never be completed. However, communication deadlock can not be prevented by resource pre-allocation, serial execution, or maintenance of safe states cause it can not occur in interleaved code execution. And also it is the most expensive dead states to correct. As a result, the users must design processes in communication deadlock before they can complete service.