linux 多線程基礎

參考出處：http://www.cnblogs.com/skynet/archive/2010/10/30/1865267.html

一、進程與線程

    進程是程序代碼在系統中的具體實現。進程是擁有所需資源和執行方案的集合。

    線程是進程中劃分出的可獨立執行的一個控制流程。

    二者區別：

        每一個進程有各自獨立的地址空間。進程崩潰不會影響到其餘進程。

        全部線程共享同一進程的資源，除了局部變量和堆以外。線程的崩潰會致使所在進程的掛起。

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <errno.h>
#include <unistd.h>

int g_Flag = 0;
 
void* thread1( void* );
void* thread2( void* );

int main( int argc, char* argv[] )
{
    printf(" Enter main\n ");

    pthread_t tid1, tid2;
    int rc1 = 0;
    int rc2 = 0;

    rc2 = pthread_create( &tid2, NULL, thread2, NULL );
    if ( 0 != rc2 )
    {
        printf("%s: %d\n", __func__, strerror(rc2) );
    }

    rc1 = pthread_create( &tid1, NULL, thread1, NULL );
    if ( 0 != rc1 )
    {
        printf( "%s: %d\n", __func__, strerror( rc1 ) );
    }
    printf( "leave main\n" );


    getchar();

    exit( 0 );
}

void* thread1( void* arg )
{    
    printf( "Enter thread1\n" );
    printf( "This is thread1, g_Flag : %d, thread id is %u\n", g_Flag, ( unsigned int )pthread_self()  );
    g_Flag = 1; 
    printf( "This is thread1, g_Flag : %d, thread_id is %u\n", g_Flag, ( unsigned int )pthread_self()  );
    printf( "leave thread\n" );
    pthread_exit( 0 );
}

void* thread2( void* arg )
{
    printf( "Enter thread2\n" );
    printf( "This is thread2, g_Flag : %d, thread_id is %u\n", g_Flag, (unsigned int )pthread_self() );
    g_Flag = 2; 
    printf( "This is thread2, g_Flag :%d, thread_id is %u\n", g_Flag, (unsigned int )pthread_self() );
    pthread_exit( 0 );
}