(基于LINUX的操作系統(tǒng)實(shí)驗(yàn)教程)(最終版)

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1、b；*WaitonthejobqueuesemahoreIfitsvalueisositive,indicatingthatthequeueisnotemty,decrementthecountbyIfthequeueisemty,blockuntilanewjobisenqueued*sem_wait(amjob_queue_count)；*Lockthemutexonthejobqueue*thread_mutex_lock(amjob_queue_mutex)；*Becauseofthesemahore,weknowthequeueisnotemtyGetthenextavailablejob*next_job=job_queue；*Removethisjobfromthelist*job_queue=job_queuegtnext；*Unlockthemutexonthejobqueuebecausewe’redonewiththequeuefornow*thread_mutex_unlock(amjob_queue_mutex)；*Carryoutthework*rocess_job(next_job)；*Cleanu*free(next_job)；}returnNULL；}*Addanewjobtothefrontofthejobqueue*voidenqueue_job(*Passjobsecificdatahere*){structjob*new_job；*Allocateane。

2、else{*Getthenextavailablejob*next_job=job_queue；*Removethisjobfromthelist*job_queue=job_queuegtnext；}*Unlockthemutexonthejobqueuebecausewe’redonewiththequeuefornow*thread_mutex_unlock(amjob_queue_mutex)；*Wasthequeueemty?Ifso,endthethread*if(next_job==NULL)eak；*Carryoutthework*rocess_job(next_job)；*Cleanu*free(next_job)；}returnNULL；}．POSIX：SEM無(wú)名信號(hào)量POSIX：SEM信號(hào)量是一個(gè)sem_t類型的變量。()聲明一個(gè)信號(hào)量并對(duì)其進(jìn)行初始化下面的代碼聲明了一個(gè)名為sem的信號(hào)量變量。includesem_tsem；必須在使用POSIX：SEM信號(hào)量之前對(duì)其進(jìn)行初始化。初始化函數(shù)：intsem_init(sem_t*sem,intshared,unsignedvalue)；參數(shù)shared=說(shuō)明只能由初始化這個(gè)信號(hào)量的進(jìn)程的線程才能使用該信號(hào)量，若shared為非，任何可以訪問(wèn)sem的進(jìn)程都可以使用這個(gè)信號(hào)量。參數(shù)value設(shè)置信號(hào)量的初始值。()對(duì)信號(hào)量的操作sem_ost函數(shù)實(shí)現(xiàn)了經(jīng)典的信號(hào)量signal操作。sem_wait函數(shù)實(shí)現(xiàn)了經(jīng)典的信號(hào)量wait操作。

3、ar_rint_arms*)arameters；inti；for(i=；icount；++i)futc(gtcharacter,stderr)；returnNULL；}*Themainrogram*intmain(){thread_tthread_id；thread_tthread_id；structchar_rint_armsthread_args；structchar_rint_armsthread_args；*Createanewthreadtorint,'x's*thread_argscharacter='x'；thread_argscount=；thread_create(amthread_id,NULL,amchar_rint,amthread_args)；*Createanewthreadtorint,o's*thread_argscharacter='o'；thread_argscount=；thread_create(amthread_id,NULL,amchar_rint,amthread_args)；thread_join(thread_id,NULL)；thread_join(thread_id,NULL)；return；}．線程實(shí)現(xiàn)同步與互斥．互斥GNULinux提供了互斥鎖mutex來(lái)實(shí)現(xiàn)線程之間的互斥。要?jiǎng)?chuàng)建一個(gè)互斥鎖，首先定義一個(gè)thread_mutex_t類型的變量，然后調(diào)用thread_mutex_init函數(shù)。例如：thread_mutex_tmutex；t。

4、。intsem_ost(sem_tsem)；intsem_wait(sem_tsem)；舉例：_cincludeincludeincludestructjob{*Linkfieldforlinkedlist*structjob*next；*Otherfieldsdescribingworktobedone*}；*Alinkedlistofendingjobs*structjob*job_queue；*Amutexrotectingjob_queue*thread_mutex_tjob_queue_mutex=PTHREAD_MUTEX_INITIALIZER；*Asemahorecountingthenumberofjobsinthequeue*sem_tjob_queue_count；*Performonetimeinitializationofthejobqueue*voidinitialize_job_queue(){*Thequeueisinitiallyemty*job_queue=NULL；*InitializethesemahorewhichcountsjobsinthequeueItsinitialvalueshouldbezero*sem_init(amjob_queue_count,,)；}*Processqueuedjobsuntilthequeueisemty*void*thread_function(void*arg){while(){structjob*next_jo。

5、hread_mutex_init(ammutex,NULL)；thread_mutex_init函數(shù)的第二個(gè)參數(shù)為mutex的屬性，若為空，則使用缺省的屬性。另一種建立使用缺省屬性的互斥鎖的方式是：thread_mutex_tmutex=PTHREAD_MUTEX_INITIALIZER；加鎖操作使用函數(shù)thread_mutex_lock解鎖操作使用函數(shù)thread_mutex_unlock例如：_cincludeincludestructjob{*Linkfieldforlinkedlist*structjob*next；*Otherfieldsdescribingworktobedone*}；*Alinkedlistofendingjobs*structjob*job_queue；*Amutexrotectingjob_queue*thread_mutex_tjob_queue_mutex=PTHREAD_MUTEX_INITIALIZER；*Processqueuedjobsuntilthequeueisemty*void*thread_function(void*arg){while(){structjob*next_job；*Lockthemutexonthejobqueue*thread_mutex_lock(amjob_queue_mutex)；*Nowit’ssafetocheckifthequeueisemty*if(job_queue==NULL)next_job=NULL；。

6、eadtorint,o's*thread_argscharacter='o'；thread_argscount=；thread_create(amthread_id,NULL,amchar_rint,amthread_args)；return；}運(yùn)行該程序，出現(xiàn)什么問(wèn)題？分析出現(xiàn)的問(wèn)題。例：等待線程結(jié)束上述問(wèn)題的解決方法是在主線程中增加等待線程結(jié)束的函數(shù)調(diào)用thread_joinincludeintthread_join(thread_tthread,void**value_tr)；該函數(shù)將調(diào)用線程掛起，直到第一個(gè)參數(shù)指定的線程退出為止。參數(shù)void**value_tr為指向目標(biāo)線程的返回值的指針提供了一個(gè)位置，若為NULL，調(diào)用線程保存目標(biāo)線程的返回值。程序_cincludeinclude*Parameterstorint_function*structchar_rint_arms{*Thecharactertorint*charcharacter；*Thenumberoftimestorintit*intcount；}；*Printsanumberofcharacterstostderr,asgivenbyPARAMETERS,whichisaointertoastructchar_rint_arms*void*char_rint(void*arameters){*Castthecookieointertotherighttye*structchar_rint_arms*=(structch。

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