J. Cheng, "A Classification of Tasking Deadlocks," Ada Letters, Vol. X, No. 5, pp. 110--127, May/June 1990.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....part, by the Charles Stark Draper Laboratory, Inc. and by NSF under grants IRI 8908693 and CDA 8922572. 1 Introduction Deadlock is one of the most serious problems in multitasking concurrent programming systems. As early as in the 60 s the deadlock problem was recognized and analyzed (Dijkstra[17] described it as the problem of the deadly embrace) Deadlock occurs when one or more tasks in a system are blocked by each other forever and their requirements can never be satisfied. A deadlock situation may arise if and only if the following four resource competition conditions hold in a system ....

....Buffers, In IEEE INFORCOM 86, pp. 478 487, Miami, Florida, April 1986. 67 [16] S. Cohen and D. Lehmann, Dynamic Systems and Their Distributed Termination, In Proceedings ACM SIGACT SIGOPS Symposium on Principles of Distributed Computing, pp. 29 33, Ottawa, Ontario, Canada, August 1982. [17] E. W. Dijkstra, Co operating Sequential Processes, In F. Genuys, editor, Programming Languages, pp. 43 112, Academic Press, New York, 1968. 18] E. W. Dijkstra, W. H. J. Feijen, and A. J. M. van Gasteren, Derivation of a Termination Detection Algorithm for Distributed Computations, ....

J. Cheng, "A Classification of Tasking Deadlocks," Ada Letters, Vol. X, No. 5, pp. 110--127, May/June 1990.

....: 339 Concise overview. 340 10.2.1. Coffman and Denning [CD73] 340 10.2.2. Complexity of static synchronization analysis: Taylor [Tay83a] 341 10.2.3. Classification of Ada deadlocks: Cheng [Che90] 343 10.3. Static nontermination anomaly detection. 345 Concise overview. 345 10.3.1. Flow graph methods. 346 Concise overview. ....

....of strategies for deadlock management to include static deadlock detection. Taylor [Tay83a] characterizes the complexity of static analysis of synchronization, including analysis of deadlock and CHT . In Section 10.2.2, we relate these complexity results to our own work. Lastly, Cheng [Che90] provides a specific enumeration of types of deadlocks which may occur in Ada. In Section 10.2.3, we discuss which of these are, and are not, covered by our Ada deadlock analysis algorithm, and the problems which must be solved to cover all the deadlock types Cheng lists. 10.2.1 Coffman and ....

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J. Cheng. A classification of tasking deadlocks. Ada Letters, pages 110--127, May/June 1990.

....is needed to enable working well for deadlock resolution, the detection method need to explicitly distinguish deadlocked tasks from livelocked tasks. A number of papers dealt with the tasking deadlock problem in Ada 83 programs and proposed various methods and tools to detect tasking deadlocks[2, 3, 6]. These methods and tools can be classified into two categories: static detection methods and dynamic detection methods. From the viewpoint of completeness and soundness, the current best result is our dynamic detection method which can certainly detect all types of tasking deadlocks, without ....

.... arc classified digraph, named the Task Wait For Graph (TWFG for short) which explicitly represents these various types of waiting relations in an execution of an Ada 95 program, was defined formally[5] TWFG was originally proposed for formal classification of tasking deadlocks in Ada 83 programs[2]. In TWFG, vertices indicate any tasking objects. A tasking object in an execution state of a concurrent Ada program is any one of the following: a task whose activation has been initiated and whose state is not terminated, a block statement that is being executed by a task, a subprogram that is ....

Cheng, J. (1990) A Classification of Tasking Deadlocks, ACM Ada Letters, 10/5, 110127.

....95, were defined for Ada 83 in the terminology of Ada 83. If we consider that different combinations of the waiting relations form different tasking deadlocks, then, by a complete classification, it is known that there are 18 different types of tasking deadlocks which may occur in Ada 83 programs [3]. Since activation waiting, finalization waiting, completion waiting, acceptance waiting, and entry calling waiting still exist in Ada 95 without intrinsic change, all 18 types of tasking deadlocks still may occur in Ada 95 programs. Now, let us turn to the new features of the Ada 95 tasking model ....

....a kind of arc classified digraph, named the Task Wait For Graph (TWFG for short) which explicitly represents various types of task synchronization waiting relations in an execution of an Ada program. TWFG was originally proposed for formal classification of tasking deadlocks in Ada 83 programs [3]. It has been used as a formal model for detection of tasking deadlocks in Ada 83 programs [5] Below, we extend the TWFG to Ada 95 programs. Definition 7. A digraph is an ordered pair (V, A) where V is a finite set of elements, called vertices, and A is a finite set of elements of the Cartesian ....

Cheng, J.: A Classification of Tasking Deadlocks, ACM Ada Letters, Vol.10, No.5 (1990) 110-127

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