计算机科学与技术：VB.NET应用教程 978-7-302-09622-1 Advanced VB.NET Chapter 8

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1、Chapter8MultithreadingObjectivesWhatismultithreadingDeclaringaThreadRunningaThreadTimeSlicingandThreadPriorityCoordinatingThreadsSleepingThreadsAbortingaThreadSharingData,Synchronization,andDeadlocksLab8:ExercisingMultithreadingSuggestedHomeAssignments2Copyright2004PearsonEdu

2、cation,Inc.WhatisMultithreadingMultitaskingTheabilityofacomputertorunmorethanonetaskorprogramatatime,Atleastinwhatseemstobeatthesametime.Example:enablesacomputertorunaword-processorandemailandahostofotherprogramsatthesametimewhilegivingtheimpressionthateachisrunningallbyitsel

3、fandallthetime.Inrealityhoweveronlyonetaskatatimecanrunoneachprocessor,CPU.3Copyright2004PearsonEducation,Inc.WhatisMultithreadingMultithreadingMultithreadingdoesthesameasmultitaskingbutatatasklevel.Multithreadingwillallowmanyelementsofthesametask(thesearethreads)torunsimulta

4、neously.Forexample,Word(ataskunderWindows)mayprintadocument(onethread)whileatthesametimetheuseristypinginanotherdocument(secondthread).4Copyright2004PearsonEducation,Inc.WhentoApplyMultithreadingWhenthereisagoodreasontohaveseveralactivitiesofthesameprogramrunningatthesametime

5、.Extraordinarylonguserinterfacefunctionswhereitisinconceivabletohavetheapplicationlockeduntilthatoperationcompleted.SavingadocumentinWordwhileallowingtheusertocontinueeditinganotherdocument.Whenthefunctionalitythattheprogramperformsnaturallydivideupintoseparateandunrelatedfun

6、ctionsSavingadocumentwhileeditinganotherdocument.5Copyright2004PearsonEducation,Inc.DiscussionInwhatothercasesismultitaskingnecessary?6Copyright2004PearsonEducation,Inc.ObjectivesWhatismultithreadingDeclaringaThreadRunningaThreadTimeSlicingandThreadPriorityCoordinatingThreads

7、SleepingThreadsAbortingaThreadSharingData,Synchronization,andDeadlocksLab8:ExercisingMultithreadingSuggestedHomeAssignments7Copyright2004PearsonEducation,Inc.DeclaringaThreadStartanewmethodandrunitindependentlyofthecurrentmethod.Thismakesitanewthread.Thethreadmustbeamethodina

8、newclassbecausethethreadwillberunningindependentlyoftheclassinwhichi