Distributed Systems Communications And Exclusive Access To Shared Resources And To Achieve

With the increasing information requirement, server system of ISP(internet server provider) is being faced with tremendous tension. Some exorbitant great server could be resolve the question, but can't come up with the increasing frequency of accessing. With the rapid development of the computer network, distributed applications become main stream gradually. In order to meet the need of distributed and parallel server system, which has high performance, high scalability and with a reasonable price, we have entirely developed DPS that is a distributed and parallel system based on Linux kernel. BOD server system is just a typical example, in future DPS will be applied in electron government affair and business affairs and so on.In the first part of this thesis,we firstly discuss some design issues and character in distributed system and then introduce some Linux kernel information briefly,lastly describe the framework and the character of DFS。In the second part,this thesis describe the upgrade of LKCC and the implement of net mutual exclusion,including the ameliorating of communication session mechanism,the implement of multi-send and preferential sending of emergent message, and DPHC algorithm.LKCC,a Linux Kernel Concurrent Communication mechanism,uses Object Transfer Protocol to send and receive data。In order to improving system processing capability and to response client requests, session mechanism is changed;because a great of source have several copy, multi-send is added;because DPS often has great load, some emergent message cannot be send duly;capability of system is depressed, message PRI is added to LKCC.DPHC uses auto-transfer to imply dependability and chooses interceder by the name of source. Because it distributes interceders of different source to each node in system, lets each interceder work as controlling node in centralizing control arithmetic, it has message number of centralizing control arithmetic and load equilibrium of distributed arithmetic. Characteristic of auto-transfer brings dependability of distributed arithmetic, because while a node has down, other nodes'requests that had been sent to it can send to other nodes by producing new interceder. So DPHC can satisfy completely need of dependability.