ceph bluestore源碼分析：C++ 擷取線程id

閱讀ceph源碼過程中需要明确目前操作是由哪個線程發出，此時需要根據線程id來确認線程名稱

C++擷取線程id是通過系統調用來直接擷取

函數描述

頭檔案:​

​<sys/syscall.h>​

​​ 函數名稱:​

​syscall(SYS_gettid)​

​ 該函數直接傳回了一個pid_t int類型的數字，即為目前線程id

此外函數​

​pthread_self​

​​同樣能夠擷取線程id,但是該函數擷取到的線程id為posix的線程id,并不是真實的線程id.是以最後擷取到的數值是一個特别長的辨別，并非​

​top -Hp pid​

​中的實際線程id

函數使用

編寫如下代碼：

#include <iostream>
#include <unistd.h>
#include <sys/types.h>
#include <stdio.h>
#include <sys/syscall.h>
#include <pthread.h>
#define gettid() syscall(SYS_gettid)
using namespace std;

void *threadFunc(void *p)
{
        printf("go into threadfunc ,pthread_self id is %d\n",pthread_self());
        printf("go into  threadfunc ,gettid id is %d \n",gettid());
        int i = 0;
        while(1)
        {
                i++;
                sleep(1);
        }
        return NULL;
}

int main()
{
        printf("man thread  tid is %d \n man pid is %d\n",gettid(),getpid());
        pthread_t id;
        pid_t tid;
        pthread_create (&id, NULL, threadFunc, NULL);
        pthread_create (&id, NULL, threadFunc, NULL);
        pthread_create (&id, NULL, threadFunc, NULL);
        int i=0;
        while (1)
        {
                i++;
                sleep(1);
        }
        return 0;
}      

運作結果如下：

[root@node1 ~]# ./a.out 
man thread  tid is 28244 
 man pid is 28244
go into threadfunc ,pthread_self id is -1511180544
go into  threadfunc ,gettid id is 28245 
end and get the tgkill tid is -1
go into threadfunc ,pthread_self id is -1527965952
go into threadfunc ,pthread_self id is -1519573248
go into  threadfunc ,gettid id is 28246 
go into  threadfunc ,gettid id is 28247      

[root@node1 ~]# ps -ef|grep a.out
root     28244 21581  0 09:41 pts/10   00:00:00 ./a.out
root     28902  8965  0 09:41 pts/7    00:00:00 grep --color=auto a.out
[root@node1 ~]# ps -Tp 28244  
  PID  SPID TTY          TIME CMD
28244 28244 pts/10   00:00:00 a.out
28244 28245 pts/10   00:00:00 a.out
28244 28246 pts/10   00:00:00 a.out
28244 28247 pts/10   00:00:00 a.out