mingw沒法編譯多線程程序的問題及解決

在linux環境下，用gedit+gcc方式學習一段時間的c語言，發現本身愈來愈佩服linux的牛人了。
竟然不用IDE也能開發代碼。我作不到，因此有回到了windows的懷抱。

mingw是windows版本的gnu c/c++工具集 主要包括編譯器gcc,鏈接器make，調試器gdb
Eclipse是很好用的開發Java的IDE，CDT的全稱是C/C++ Development Tools，是使Eclipse可以支持C/C++開發的插件。
本人使用的開發環境以下:
win7+eclipse +MinGW + CDT

本文的目的：
1）使用eclipse、MingW獨構建Windows版的c/c++開發環境
2）編譯並調通了一個多線程的程序
eclipse、MingW的安裝此處不作重點。

一、配置C/C++開發環境
右擊個人電腦，點屬性->高級->環境變量。而後：
1）在PATH里加入C:\MinGW\bin
2）新建LIBRARY_PATH變量，值設爲C:\MinGW\lib，這是標準庫的位置。
3）新建C_INCLUDE_PATH變量，值設爲C:\MinGW\include。
4）新建CPLUS_INCLUDE_PATH變量，值爲C:\MinGW\include\c++\3.4.2;C:\MinGW\include\c++\3.4.2\mingw32;C:\MinGW\include\c++\3.4.2\backward;C:\MinGW\include

二、設置eclipse的環境變量
Eclipse的Project->Properties->C/C++ Build->Environment中去查看對應的PATH變量
主要是看有沒有添加一個包含MinGW的bin目錄的PATH變量。這個變量在建立工程的時候通常會自動添加。
但若是沒有正確設置PATH變量，編譯的時候就會報錯說不能運行g++或者gcc。

三、設置多線程動態連接庫
Project->Properties->C/C++Build->Settings->Tool Settings->GCC C++ Linker->Libraries
添加Libraries (-l): lpthread

四、一個簡單的線程池的例子

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <pthread.h>
#include <assert.h>

typedef struct worker
{
void *(*process) (void *arg);
void *arg;
struct worker *next;

} CThread_worker;

typedef struct
{
pthread_mutex_t queue_lock;
pthread_cond_t queue_ready;

CThread_worker *queue_head;

int shutdown;
pthread_t *threadid;
int max_thread_num;
int cur_queue_size;

} CThread_pool;

int pool_add_worker (void *(*process) (void *arg), void *arg);
void *thread_routine (void *arg);

static CThread_pool *pool = NULL;
void
pool_init (int max_thread_num)
{
pool = (CThread_pool *) malloc (sizeof (CThread_pool));

pthread_mutex_init (&(pool->queue_lock), NULL);
pthread_cond_init (&(pool->queue_ready), NULL);

pool->queue_head = NULL;

pool->max_thread_num = max_thread_num;
pool->cur_queue_size = 0;

pool->shutdown = 0;

pool->threadid =
(pthread_t *) malloc (max_thread_num * sizeof (pthread_t));
int i = 0;
for (i = 0; i < max_thread_num; i++)
{
pthread_create (&(pool->threadid[i]), NULL, thread_routine,
NULL);
}
}

int
pool_add_worker (void *(*process) (void *arg), void *arg)
{
CThread_worker *newworker =
(CThread_worker *) malloc (sizeof (CThread_worker));
newworker->process = process;
newworker->arg = arg;
newworker->next = NULL;

pthread_mutex_lock (&(pool->queue_lock));
CThread_worker *member = pool->queue_head;
if (member != NULL)
{
while (member->next != NULL)
member = member->next;
member->next = newworker;
}
else
{
pool->queue_head = newworker;
}

assert (pool->queue_head != NULL);

pool->cur_queue_size++;
pthread_mutex_unlock (&(pool->queue_lock));
pthread_cond_signal (&(pool->queue_ready));
return 0;
}

int
pool_destroy ()
{
if (pool->shutdown)
return -1;
pool->shutdown = 1;

pthread_cond_broadcast (&(pool->queue_ready));

int i;
for (i = 0; i < pool->max_thread_num; i++)
pthread_join (pool->threadid[i], NULL);
free (pool->threadid);

CThread_worker *head = NULL;
while (pool->queue_head != NULL)
{
head = pool->queue_head;
pool->queue_head = pool->queue_head->next;
free (head);
}
pthread_mutex_destroy(&(pool->queue_lock));
pthread_cond_destroy(&(pool->queue_ready));

free (pool);
pool=NULL;
return 0;
}

void * thread_routine (void *arg)
{
printf ("starting thread 0x%x\n", pthread_self ());
while (1)
{
pthread_mutex_lock (&(pool->queue_lock));
while (pool->cur_queue_size == 0 && !pool->shutdown)
{
printf ("thread 0x%x is waiting\n", pthread_self ());
pthread_cond_wait (&(pool->queue_ready), &(pool->queue_lock));
}

if (pool->shutdown)
{
pthread_mutex_unlock (&(pool->queue_lock));
printf ("thread 0x%x will exit\n", pthread_self ());
pthread_exit (NULL);
}

printf ("thread 0x%x is starting to work\n", pthread_self ());

assert (pool->cur_queue_size != 0);
assert (pool->queue_head != NULL);

pool->cur_queue_size--;
CThread_worker *worker = pool->queue_head;
pool->queue_head = worker->next;
pthread_mutex_unlock (&(pool->queue_lock));

(*(worker->process)) (worker->arg);
free (worker);
worker = NULL;
}
pthread_exit (NULL);
}

// 下面是測試代碼

void * myprocess (void *arg)
{
printf ("threadid is 0x%x, working on task %d\n", pthread_self (),*(int *) arg);
_sleep (1);
return NULL;
}

int main (int argc, char **argv)
{
pool_init (3);

int *workingnum = (int *) malloc (sizeof (int) * 10);
int i;
for (i = 0; i < 10; i++)
{
workingnum[i] = i;
pool_add_worker (myprocess, &workingnum[i]);
}
_sleep (5);
pool_destroy ();

free (workingnum);
return 0;
}

五、問題及解決方法
1）build project時出現「Error launching builder (make -k all )」
先將C:\MinGW\bin底下的
mingw32-make.exe改名爲make.exe，由於在Eclipse使用時它預設會抓系統裏make這個文件名而不是mingw32-make.

2）build project時出現「launch failed,binary not found」
報錯是由於沒有指定編譯器。爲了讓CDT可以採用MinGW進行編譯，須要在 Eclipse 中進行設定
方法一：去Window->Preferences->C/C++->New CDT project wizard->Makefile Project下，找到 Binary Parser 取消 Elf Parser 改選 PE Windows Parser。或是其餘編譯器，看具體狀況而定，
固然你也能夠指定GNU ELF Parser。
方法二：去projrct -> properties -> c/c++ build -> settings ->Binary Parser下設置一下，好比使用GNU Elf Parser

3）undefined reference to 'pthread_create'
undefined reference to 'pthread_join'
問題緣由：
pthread 庫不是 Linux 系統默認的庫，因爲Mingw下沒有帶，因此在項目中設置多線程動態連接庫，也無論用。
ftp://sourceware.org/pub/pthreads-win32/pthreads-w32-2-8-0-release.exe
解開pthreads-w32-2-8-0-release.exe，把Pre- built.2中的libpthreadGC2.a更名爲libpthread.a複製到c:\mingw\lib目錄，
pthread.h複製到c: \mingw\include目錄便可解決

本文歡迎轉載，轉載請註明做者與出處
做者：流星
出處：http://blog.sina.com.cn/staratsky