摘要：基本線程的動(dòng)作繼續(xù)之前語(yǔ)言線程的文章文章文章來(lái)了解基本的線程操作。屬性用完后對(duì)其進(jìn)行清理回收通過(guò)共享的變量來(lái)檢測(cè)子線程是否已經(jīng)結(jié)束代碼如下設(shè)置調(diào)度屬性線程庫(kù)提供以下調(diào)度策略先進(jìn)先出調(diào)度。

繼續(xù)之前C語(yǔ)言線程的文章:文章1 文章2 來(lái)了解基本的線程操作。

下面代碼中關(guān)鍵的地方在于：

通過(guò) res = pthread_attr_init(&thread_attr); 初始化一個(gè)線程屬性

通過(guò) res = pthread_attr_setdetachstate(&thread_attr, PTHREAD_CREATE_DETACHED); 將屬性設(shè)置為脫離狀態(tài)(PTHREAD_CREATE_DETACHED),即不能通過(guò)調(diào)用 pthread_join 來(lái)獲得另一個(gè)線程的退出狀態(tài)

另外還有一個(gè)常用的默認(rèn)狀態(tài)是 PTHREAD_CREATE_JOINABLE ,可以允許兩個(gè)線程重新合并。

屬性用完后對(duì)其進(jìn)行清理回收 (void)pthread_attr_destroy(&thread_attr);

通過(guò)共享的變量 thread_finished 來(lái)檢測(cè)子線程是否已經(jīng)結(jié)束

代碼如下:

#include 
#include 
#include 
#include 

void *thread_function(void *arg);

char message[] = "Hello World";
int thread_finished = 0;

int main() {
  int res;
  pthread_t a_thread;

  pthread_attr_t thread_attr;

  res = pthread_attr_init(&thread_attr);
  if (res != 0) {
    perror("Attribute creation failed");
    exit(EXIT_FAILURE);
  }
  res = pthread_attr_setdetachstate(&thread_attr, PTHREAD_CREATE_DETACHED);
  if (res != 0) {
    perror("Setting detached attribute failed");
    exit(EXIT_FAILURE);
  }
  res = pthread_create(&a_thread, &thread_attr, thread_function, (void *)message);
  if (res != 0) {
    perror("Thread creation failed");
    exit(EXIT_FAILURE);
  }
  (void)pthread_attr_destroy(&thread_attr);
  while(!thread_finished) {
    printf("Waiting for thread to say it"s finished...
");
    sleep(1);
  }
  printf("Other thread finished, bye!
");
  exit(EXIT_SUCCESS);
}

void *thread_function(void *arg){
  printf("thread_function is running. Argument was %s
", (char *)arg);
  sleep(4);
  printf("Second thread setting finished flag, and exiting now
");
  thread_finished = 1;
  pthread_exit(NULL);
}

線程庫(kù)提供以下調(diào)度策略:

| SCHED_FIFO  | 先進(jìn)先出 (FIFO) 調(diào)度。每個(gè)線程都有一個(gè)固定的優(yōu)先級(jí)；當(dāng)多個(gè)線程具有相同的優(yōu)先級(jí)時(shí)，它們按照先進(jìn)先出 (FIFO) 的順序運(yùn)行直到完成 |
| SCHED_RR    | 循環(huán) (RR) 調(diào)度。每個(gè)線程都有固定的優(yōu)先級(jí)；當(dāng)多個(gè)線程具有相同的優(yōu)先級(jí)時(shí)，它們按照先進(jìn)先出 (FIFO) 的順序在一個(gè) 固定的時(shí)間片內(nèi)運(yùn)行。 |
| SCHED_OTHER | 缺省的 AIX? 調(diào)度。每個(gè)線程都有一個(gè)由調(diào)度程序根據(jù)線程的活動(dòng)動(dòng)態(tài)修改的初始優(yōu)先級(jí)；線程的執(zhí)行是按時(shí)間分割的。在其他系統(tǒng)上，這個(gè)調(diào)度策略可能會(huì)不同。 |

設(shè)置調(diào)度屬性和設(shè)置很相似:

#include 
#include 
#include 
#include 

void *thread_function(void *arg);

char message[] = "Hello World";
int thread_finished = 0;

int main() {
    int res;
    pthread_t a_thread;
    pthread_attr_t thread_attr;

    int max_priority;
    int min_priority;
    struct sched_param scheduling_value;

    res = pthread_attr_init(&thread_attr);
    if (res != 0) {
        perror("Attribute creation failed");
        exit(EXIT_FAILURE);
    }
    res = pthread_attr_setschedpolicy(&thread_attr, SCHED_OTHER);
    if (res != 0) {
        perror("Setting schedpolicy failed");
        exit(EXIT_FAILURE);
    }
    res = pthread_attr_setdetachstate(&thread_attr, PTHREAD_CREATE_DETACHED);
    if (res != 0) {
        perror("Setting detached attribute failed");
        exit(EXIT_FAILURE);
    }
    res = pthread_create(&a_thread, &thread_attr, thread_function, (void *)message);
    if (res != 0) {
        perror("Thread creation failed");
        exit(EXIT_FAILURE);
    }
    max_priority = sched_get_priority_max(SCHED_OTHER);
    min_priority = sched_get_priority_min(SCHED_OTHER);
    scheduling_value.sched_priority = min_priority;
    res = pthread_attr_setschedparam(&thread_attr, &scheduling_value);
    if (res != 0) {
        perror("Setting schedpolicy failed");
        exit(EXIT_FAILURE);
    }
    (void)pthread_attr_destroy(&thread_attr);
    while(!thread_finished) {
        printf("Waiting for thread to say it"s finished...
");
        sleep(1);
    }
    printf("Other thread finished, bye!
");
    exit(EXIT_SUCCESS);
}

void *thread_function(void *arg) {
    printf("thread_function is running. Argument was %s
", (char *)arg);
    sleep(4);
    printf("Second thread setting finished flag, and exiting now
");
    thread_finished = 1;
    pthread_exit(NULL);
}

通過(guò) int pthread_cancel(pthread_t thread); 來(lái)請(qǐng)求一個(gè)線程終止

通過(guò) int pthread_setcancelstate(int state, int *oldstate) 來(lái)設(shè)置接受的進(jìn)程是允許取消請(qǐng)求還是忽略它

通過(guò) int pthread_setcanceltype(int type, int *oldtype) 來(lái)設(shè)置取消類(lèi)型, PTHREAD_CANCEL_ASYCHRONOUS 代表接收到取消請(qǐng)求后立即行動(dòng)， THREAD_CANCEL_DEFERRED 表示在接收到請(qǐng)求后，等待函數(shù)執(zhí)行下述動(dòng)作之一后才取消線程: pthread_join, pthread_cond_wait, pthread_cond_timeout, pthread_test_cancel, sem_wait, sigwait 等

代碼如下:

#include 
#include 
#include 
#include 

void *thread_function(void *arg);

int main () {
  int res;
  pthread_t a_thread;
  void *thread_result;

  res = pthread_create(&a_thread, NULL, thread_function, NULL);
  if (res != 0){
    perror("Thread creation failed");
    exit(EXIT_FAILURE);
  }
  sleep(3);
  printf("Caceling thread...
");
  res = pthread_cancel(a_thread);
  if (res != 0){
    perror("Thread cancelation failed");
    exit(EXIT_FAILURE);
  }
  printf("Waiting for thread to finish...
");
  res = pthread_join(a_thread, &thread_result);
  if (res != 0) {
    perror("Thread join failed");
    exit(EXIT_FAILURE);
  }
  exit(EXIT_SUCCESS);
}

void *thread_function(void *arg) {
  int i, res;
  res = pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);
  if (res != 0) {
    perror("Thread pthread_setcalcelstate failed");
    exit(EXIT_FAILURE);
  }
  res = pthread_setcanceltype(PTHREAD_CANCEL_DEFERRED, NULL);
  if (res != 0) {
    perror("Thread pthread_setcanceltype failed");
    exit(EXIT_FAILURE);
  }
  printf("thread_function is running
");
  for(i=0; i<10; i++) {
    printf("Thread is still running (%d)...
", i);
    sleep(1);
  }
  pthread_exit(0);
}

代碼如下：

#include 
#include 
#include 
#include 

#define NUM_THREADS 6

void *thread_function(void *arg);

int main() {
    int res;
    pthread_t a_thread[NUM_THREADS];
    void *thread_result;
    int lots_of_threads;

    for(lots_of_threads = 0; lots_of_threads < NUM_THREADS; lots_of_threads++) {

        res = pthread_create(&(a_thread[lots_of_threads]), NULL, thread_function, (void *)&lots_of_threads);
        if (res != 0) {
            perror("Thread creation failed");
            exit(EXIT_FAILURE);
        }
        sleep(1);
    }
    printf("Waiting for threads to finish...
");
    for(lots_of_threads = NUM_THREADS - 1; lots_of_threads >= 0; lots_of_threads--) {
        res = pthread_join(a_thread[lots_of_threads], &thread_result);
        if (res == 0) {
            printf("Picked up a thread
");
        }
        else {
            perror("pthread_join failed");
        }
    }
    printf("All done
");
    exit(EXIT_SUCCESS);
}

void *thread_function(void *arg) {
    int my_number = *(int *)arg;
    int rand_num;

    printf("thread_function is running. Argument was %d
", my_number);
    rand_num=1+(int)(9.0*rand()/(RAND_MAX+1.0));
    sleep(rand_num);
    printf("Bye from %d
", my_number);
    pthread_exit(NULL);
}

運(yùn)行結(jié)果如下:

thread_function is running. Argument was 0
Bye from 0
thread_function is running. Argument was 1
thread_function is running. Argument was 2
Bye from 1
thread_function is running. Argument was 3
thread_function is running. Argument was 4
thread_function is running. Argument was 5
Waiting for threads to finish...
Bye from 5
Picked up a thread
Bye from 3
Bye from 2
Bye from 4
Picked up a thread
Picked up a thread
Picked up a thread
Picked up a thread
Picked up a thread
All done

Posix多線程編程—線程屬性

《Linux 程序設(shè)計(jì)》

http://www.ibm.com/support/kn...

不得不承認(rèn)，我失敗了。曾計(jì)劃每天分享一篇python相關(guān)知識(shí)點(diǎn)但沒(méi)有做到。失敗的原因想找可以找很多比如最近在做一個(gè)小的項(xiàng)目、這幾天出去聚會(huì)沒(méi)有時(shí)間、工作出現(xiàn)問(wèn)題加班到比較晚等等，然而總結(jié)起來(lái)不外乎在心里它的重要程度是怎么樣的。我反思了下幾乎做到一天一篇的這一個(gè)月過(guò)程做出改變，不再要求一天一篇，而是當(dāng)我有好的素材要分享時(shí)才分享，這樣與我與大家都是一件好事，我可以動(dòng)態(tài)調(diào)度自己的精力和注意力，比如最近實(shí)現(xiàn)了一半的一個(gè)odoo項(xiàng)目依賴(lài)關(guān)系分析器可以盡快把它做完，對(duì)于讀者來(lái)說(shuō)也可以減少干擾看到更好的分享而不是像我之前有幾篇那樣劃水的。但每周應(yīng)該會(huì)有3-4篇Python的知識(shí)可以分享。另外我目前的工作是基于Odoo的，我計(jì)劃嘗試做一些基礎(chǔ)的教程來(lái)分享這個(gè)我熟悉的框架，如果有進(jìn)展一定會(huì)告知感興趣的讀者。感謝讀者。

最后向漩渦鳴人致敬，朝他的“說(shuō)到做到，這就是我的忍道”努力。