• 作者： 吳昭正; 連秀婂; 袁賢銘
• 作者服務機構： 交通大學資訊科學系
• 中文摘要： 對於解決並行程序間（concurrent process）的同步（synchronize）問題，信號機（semaphore）是一種優秀而且標準的機制；所以大多數作業系統都提供信號機機制讓使用者使用。本計畫主要在討論一個我們稱之為DISEM的分散式信號機（distributed semaphore）之設計與實作。DISEM是被實作在執行具有BSD socket和System V IPCs的UNIX作業系統或其相關衍生版本之工作站的應用階層上，它能夠在分散式的工作站環境下，支援信號機機制。DISEN系統的使用方法是非常簡單容易的，它的使用方式就如平常使用者在程式中呼叫程式庫中的副程序一樣簡單，不必去考慮有關網路方面的問題。除此之外，它也對工作站的毀壞（crash）提供了可容錯的服務。從初步的效能評估結果中顯示出，DISEM系統的效能是可以接受的。整體而言，DISEM是一個在分散式的工作站網路環境下有用的且具有可攜性的信號機機制。
• 英文摘要： Most operating systems provide a semaphore mechanism to users because the semaphore is anexcellent, classic mechanism for synchronizing concurrent processes. This paper describes the designand implementation of a distributed semaphore facility called DISEM (DIStributed SEMaphore)．DISEMsupports a semaphore mechanism in a distributed workstations environment, and it is implemented at theapplication level for workstations running a version or a derivative of the UNIX operating system whichsupports both BSD sockets and System V IPCs. The use of the DISEM system is made entirely transparent.It enables use of many of these library functions to be as simple across machine boundaries as withina single machine. In addition, it also provides fault tolerant service in case a workstation crashes. Inorder to distribute the server load and to enhance the reliability of the system, we distribute the shareddata onto several servers．In other words, the distributed semaphores in the system are not managed bya central server, but rather partitioned and served by several servers. The preliminary performance resultsindicate that the effectiveness of our DISEM system is acceptable. Generally speaking, DISEM is a usefuland portable facility for supporting a distributed semaphore in a local area network of workstations.
• 中文關鍵字： distributed system; interprocess communication; synchronization; distributed semaphore; fault tolerance
• 英文關鍵字： --