chap03.pptVIP

Process Termination Process executes last statement and asks the operating system to delete it (exit) Status value returned from child to parent (via wait) Process’ resources are deallocated by operating system Memory, open files, I/O buffers Parent may terminate execution of children processes (abort) with various reason Child has exceeded allocated resources Task assigned to child is no longer required If parent is exiting Some operating system do not allow child to continue if its parent terminates All children terminated - cascading termination 悍炕叔黄濒较噪铱芝映扇睦孰谐骋醒江翘骡蒂岩蹄遏凶禄舱顽惋亭润元佳chap03chap03 Cooperating Processes The Processes executing concurrently in the operating system may be either independent processes or cooperating processes Hardware Operating System UserProcess 1 UserProcess 2 差堕盖一院粳天蛾状挽潞县跨蜕哺隋赋闪亭茎离商寇带茵逾拘搽敝客巳膏chap03chap03 Cooperating Processes Independent process cannot affect or be affected by the execution of another process Cooperating process can affect or be affected by the execution of another process Advantages of process cooperation Information sharing Computation speed-up; parallelism may speed up the computation Modularity; dividing the system function into separate process Convenience; concurrently running environment. 擒匝俄产裔窟煽哥呻贫君俱雕集甚峻躯溢藤夕嚣燕灯躲拒氧引稼捍拷敏见chap03chap03 InterProcess Communication Cooperating processes require an InterProcess Communication (IPC) mechanism that will allow them to exchange data and information Hardware Operating System UserProcess 1 UserProcess 2 侥赤绿保跋寥碘棋速息蔡蒂晒靡肝契审界嘉乎软用捧轮赊弱臣则刮安中杏chap03chap03 Interprocess Communication (IPC) is a mechanism for processes to communicate and to synchronize their actions Two fundamental models Shared memory Message passing In the shared-memory model, a region of memory that is shared by cooperating process is established. IPC is performed by reading and writing data to the shared region In the message-passing model, IPC takes place by means of messages exchanged between the coope