重生線程

Question

我有這個線程FCGI應用程序，滋生N個線程，並等待他們退出

#include "vips/vips.h" 
#include "vips/vips" 
#include <stdio.h> 
#include <stdlib.h> 
#include <iostream> 
#include "tiff.h" 
#include "tiffio.h" 
#include "fastcgi.h" 
#include "fcgio.h" 
#include "Tokenizer.h" 
#include "string.h" 
#include <sstream> 
#include <pthread.h> 
#include <sys/types.h> 

using namespace std; 
using namespace vips; 

#define THREAD_COUNT 2 
static int counts[THREAD_COUNT]; 

static void *handleFcgi(void *a) 
{ 
    int rc, i, thread_id = (intptr_t)a; 
    pid_t pid = getpid(); 
    FCGX_Request request; 
    char *server_name; 

    FCGX_InitRequest(&request, 0, 0); 
    for (;;) 
    { 
     static pthread_mutex_t accept_mutex = PTHREAD_MUTEX_INITIALIZER; 
     static pthread_mutex_t counts_mutex = PTHREAD_MUTEX_INITIALIZER; 

     /* Some platforms require accept() serialization, some don't.. */ 
     pthread_mutex_lock(&accept_mutex); 
     rc = FCGX_Accept_r(&request); 
     pthread_mutex_unlock(&accept_mutex); 

     if (rc < 0 || counts[thread_id] > 5) 
      break; 

     server_name = FCGX_GetParam("SERVER_NAME", request.envp); 

     FCGX_FPrintF(request.out, 
        "Content-type: text/html\r\n" 
        "\r\n" 
        "<title>FastCGI Hello! (multi-threaded C, fcgiapp library)</title>" 
        "<h1>FastCGI Hello! (multi-threaded C, fcgiapp library)</h1>" 
        "Thread %d, Process %ld<p>" 
        "Request counts for %d threads running on host <i>%s</i><p><code>", 
        thread_id, pid, THREAD_COUNT, server_name ? server_name : "?"); 

     pthread_mutex_lock(&counts_mutex); 
     ++counts[thread_id]; 
     for (i = 0; i < THREAD_COUNT; i++) 
      FCGX_FPrintF(request.out, "%5d " , counts[i]); 
     pthread_mutex_unlock(&counts_mutex); 

     FCGX_Finish_r(&request); 
    } 

    return NULL; 
} 

int main (int argc, char **argv) 
{ 
    int i; 
    pthread_t id[THREAD_COUNT]; 
    FCGX_Init(); 

    for (i = 0; i < THREAD_COUNT; i++) 
     pthread_create(&id[i], NULL, handleFcgi, (void*) i); 

    pthread_join(id[0], NULL); 
    pthread_join(id[1], NULL); 

    return(0); 
} 

我已經設置線程5個請求後才能完成，現在因爲後來我前完成我會添加一些自定義邏輯，並且我想在完成一些請求後完全重啓線程。

我想在每次存在時產生一個線程，這可能嗎？

Answer 1

簡短的回答是，如果你讓線程退出，你必須產生一個新的線程。一旦退出線程，就不能重新啓動線程，此時系統已經拆除線程。你只需要創建一個新的線程或保持原有的活着，直到你不需要它。

好的，基於你剛剛陳述的內容，你爲什麼不考慮使用線程池，比如boost :: threadpool。這將爲您節省以瘋狂的速度產生新線程的開銷，因爲這是相當昂貴的操作。

一個線程池基本上是一個線程池，操作系統已經坐在這個線程池中，可以用來進行工作。這樣，您永遠不需要創建新線程，也不必擔心管理線程，只需交給他們工作並獲得結果。