From owner-freebsd-threads@FreeBSD.ORG Sat Nov 27 09:07:20 2004 Return-Path: Delivered-To: freebsd-threads@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 7B74F16A4CE; Sat, 27 Nov 2004 09:07:20 +0000 (GMT) Received: from smtp.rol.ru (smtp.rol.ru [194.67.21.9]) by mx1.FreeBSD.org (Postfix) with ESMTP id B9F9A43D1D; Sat, 27 Nov 2004 09:07:19 +0000 (GMT) (envelope-from alek@mts-nn.ru) Received: from ts3-a127.NNovgorod.dial.rol.ru ([212.92.142.127]:45327 "EHLO mts-nn.ru" smtp-auth: TLS-CIPHER: TLS-PEER-CN1: ) by gnome10.net.rol.ru with ESMTP id S24062AbUK0JHS (ORCPT + 1 other); Sat, 27 Nov 2004 12:07:18 +0300 Message-ID: <41A84422.6090001@mts-nn.ru> Date: Sat, 27 Nov 2004 12:08:50 +0300 From: Alexander Bubnov User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.6) Gecko/20040429 X-Accept-Language: en-us, en MIME-Version: 1.0 To: David Xu References: <41A72410.9080500@mail.ru> <41A7CA88.60505@freebsd.org> In-Reply-To: <41A7CA88.60505@freebsd.org> Content-Type: text/plain; charset=KOI8-R; format=flowed Content-Transfer-Encoding: 7bit cc: freebsd-threads@freebsd.org Subject: Re: deadlock again X-BeenThere: freebsd-threads@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Threading on FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 27 Nov 2004 09:07:20 -0000 Many thanks! I see, nevertheless why is my program deadlocked? You wanted to said this problem from race condition? But why does it work correctly under some UNIX, UNIX-like OS? David Xu wrote: > Your program has obvious race condition: > main: create thread A: > > LOOP: > > A: wait on Start > main: signal Start > main: wait on Restart > A: resumed from Start > A: Signal Restart > main: resumed from Restart > main: Create thread B > goto loop > > This demo shows FreeBSD has better throughput then others. > > David Xu > > Alexander Bubnov wrote: > >> /* >> Hello! >> Could you tell me why this exemple is deadlocked under FreeBSD, not >> Linux? >> (FreeBSD 4.10 and 5.2 , I have not tried under other versions) >> >> a string that includes this problem marked, see below the main function >> >> */ >> #include >> #include >> #include >> #include >> #include >> #include >> #include >> >> int Exit=0;/* uses in hand(), changes in main() */ >> int ReStart,Start;/* semaphores ID which returns semget() */ >> /* >> Start semphore controls starting threads, >> EXETHREADS - how many threads can start in one time >> ReStart semaphore for wait when the starting threads display a >> string >> */ >> struct sembuf dec={0},inc={0},op={0};/* they initilize in the main >> function*/ >> void*hand(void*p){ >> do{ >> semop(Start,&dec,1); >> if(Exit)break; >> puts(p); >> semop(ReStart,&inc,1); >> }while(1); >> fprintf(stderr,"bye, %s!\n",p); >> return NULL; >> } >> >> #define MAXTHREADS 5 >> #define EXETHREADS 2 /* number of threads which is executed in one >> time*/ >> #define ITERAT 2 /* number of iterations, see the main function */ >> >> int main(void){ >> char*s[MAXTHREADS]={"Mike","Leo","Don","Raph","Splinter"}; >> int i; >> pthread_t thread[MAXTHREADS]; >> /* to initlize semaphores operations */ >> dec.sem_op=-1,inc.sem_op=1,op.sem_op=EXETHREADS; >> if( -1==(Start=semget('A',1,0666|IPC_CREAT)) || >> -1==(ReStart=semget('B',1,0666|IPC_CREAT)) >> ){perror("semget");return EXIT_FAILURE;} >> /* to initilize semaphores value */ >> semctl(Start,0,SETVAL,0); >> semctl(ReStart,0,SETVAL,0); >> #ifndef linux /* may be this string is not needed, I do not know*/ >> if(pthread_setconcurrency(MAXTHREADS+1))perror("concurrency"); >> #endif >> >> /* to create the threads */ >> for(i=0;i> pthread_create(thread+i,NULL,hand,s[i]); >> for(i=0;i> puts("____START____"); >> semop(Start,&op,1); >> /* to wait EXETHREADS threads */ >> op.sem_op*=-1; >> /* >> !!! this problem is here !!! >> if I insert 'pause()' or 'while(1)' instend of >> 'semop(ReStart,&op,1)' >> that only one thread is executed two time, why? >> this code does not help too (but I can see >> names that is printed by hand()) >> op.sem_flg=IPC_NOWAIT >> while(-1==semop(ReStart,&op,1) && EAGAIN); >> */ >> semop(ReStart,&op,1); >> op.sem_op*=-1; >> puts("____FINISH____"); >> } >> /* to wait the threads to exit*/ >> semctl(Start,0,SETVAL,MAXTHREADS); >> Exit=1; >> for(i=0;i> pthread_join(thread[i],NULL); >> if( -1==semctl(ReStart,0,IPC_RMID) || >> -1==semctl(Start,0,IPC_RMID) >> ) perror("semdel"); >> return EXIT_SUCCESS; >> } >> >> _______________________________________________ >> freebsd-threads@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-threads >> To unsubscribe, send any mail to >> "freebsd-threads-unsubscribe@freebsd.org" >> >> > > _______________________________________________ > freebsd-threads@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-threads > To unsubscribe, send any mail to > "freebsd-threads-unsubscribe@freebsd.org" > >