共查询到18条相似文献,搜索用时 93 毫秒
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对于避免死锁的安全算法的改进 总被引:4,自引:1,他引:3
在每种资源只有一个个体的情况下,本文给出了一种避免死销的安全算法。该算法是对现有的一种安全算法的改进,改进后的算法被命名为触网式安全算法,该算法把以前算法的运算级次从n^2(n表示系统中进程的数目)降低为n,从而大大地节省了检测开锁。 相似文献
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为了提高传统资源安全分配算法效率,降低安全检查时的系统开销,提出了改进的资源安全分配算法。改进后的算法在每次安全检查时首先检查申请资源进程,一旦申请资源进程满足判定条件,便可以确定系统处于安全状态。不需要对系统中所有进程进行检查,缩小了安全检查范围,提高了系统效率。通过算法推理和实例验证,改进后的算法是可行且高效的,能更好地适应多任务系统中死锁避免的需要,实现资源的安全分配。 相似文献
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死锁处理是分布式系统中的关键问题,其中处理死锁最主要的手段为死锁检测。在评价死锁检测算法性能时伪死锁率被视为一项重要指标,故降低伪死锁率对提高算法性能有着促进作用,而目前大多数算法改进对伪死锁率关注较少。本文阐述了伪死锁研究的意义,并对若干种死锁检测算法的伪死锁率进行研究和模拟实验,认为现有的死锁算法可分为两类:环内检测和环无关检测。并分别通过减少冗余消息和本地死锁解决两种改进方法来降低目前算法的伪死锁率,最终实验表明算法性能获得较大提高。 相似文献
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给出了基于进程资源图的进程非阻塞的判定定理,进而给出了基于进程资源图的死锁检测算法,该算法提供了一种公式化的验算方法,可操作性强。 相似文献
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一种改进的无死锁试卷生成算法 总被引:2,自引:0,他引:2
1.引言作为计算机远程教育(网上教育)中一个必不可少的组成部分,教学评价系统(即考试系统)设计成败的关键在于网络环境下的题库管理系统的设计,这一设计主要应考虑以下几方面的问题: (1)多卷并发试卷的时间冲突。一方面,由于网络用户数目的事先不确定性和题库中试题总量有限,可能产生多份试卷争夺试题资源的现象,从而形成时间 相似文献
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众所周知,RSA是唯一一个能够同时实现数据加密、数字签名、秘钥交换的算法。其过程可简述为选取两个大的质数乘积n=p’q(非公开),然后选择一个和牵(n)互质的整数e(其中1〈e〈(b(n)),求其关于欧拉函数巾(n)=(p-1)(q-1)=φ(P)*φ(q)的逆元d,进而得到公钥对与私钥对(e,n)和(d,n)。假如n是三个或更多素数的乘积会怎样?该算法是否依然成立?本文旨在探讨n取更多素数乘积时所得到的结论以及根据这些结论所能对RSA作出的改进。 相似文献
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《Journal of Parallel and Distributed Computing》1995,31(2):112-125
This paper deals with the problem of deadlock detection in asynchronous message passing systems in a system model that covers unspecified receptions and non-FIFO channels. It presents a hierarchy of deadlock models and deadlock detection problems. It abstracts deadlocks by a general deadlock model that has the same modeling power as the OR-AND model; however, it has much concise expressive power. An abstract general definition of deadlocks in distributed systems is presented that defines deadlocks independently of the underlying deadlock model. This formulation can be used to design a single distributed deadlock detection algorithm which uniformly addresses all deadlocks in the context of various request models such as AND, OR, AND-OR, and k-out-of-n requests. A simple generalized deadlock detection algorithm that uses a circulating token is presented to illustrate the concept. The algorithm is formally described and proven correct. Moreover, possible refinements of the basic solution concerning improvements of token routing and parallel implementation are outlined and evaluated. Extensions to individual and global termination issues are also addressed. Since the proposed deadlock detection algorithm is designed around the abstract definition of deadlocks, it has some very favorable features. 相似文献
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针对普通高等教育"十一五"国家级规划教材中的渡船问题算法,进行了分析研究,说明了算法的不足之处,并给出了改进的算法。 相似文献
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Deadlock handling is an important component of transaction management in a database system. In this paper, we contribute to the development of techniques for transaction management by presenting an algorithm for detecting deadlocks in a distributed database system. The algorithm uses priorities for transactions to minimize the number of messages initiated for detecting deadlocks. It does not construct any wait-for graph but detects cycles by an edge-chasing method. It does not detect any phantom deadlock (in the absence of failures), and for the resolution of deadlocks it does not need any extra computation. The algorithm also incorporates a post-resolution computation that leaves information characterizing dependence relations of remaining transactions of the deadlock cycle in the system, and this will help in detecting and resolving deadlocks which may arise in the future. An interesting aspect of this algorithm is that it is possible to compute the exact number of messages generated for a given deadlock configuration. The complexity is comparable to the best algorithm reported. We first present a basic algorithm and then extend it to take into account shared and exclusive lock modes, simultaneous acquisition of multiple locks, and nested transactions. 相似文献
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苏瑞文 《计算机光盘软件与应用》2011,(3)
进程死锁问题是操作系统的主要问题之一,很多学者专家一直在研究怎样解决这个问题.本文针对操作系统中经常出现的死锁问题进行了讨论,阐述了死锁出现的原因、四个必要条件,以及死锁的处理方法,最后谈论了一个避免死锁的经典算法--银行家算法. 相似文献
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提出了一种新的直线生成算法,该算法通过预知每个象素行要点亮的象素点,实现了在一个象素行上同时处理多个象素。在配有块写入图形存储器的系统中,该算法可以实现并行填充要素,对小斜度直线,该算法可以避免Bresenham算法中偏差计算浪费现象。 相似文献