进程栈与线程栈的关系？

内核栈、用户栈

32位Linux系统上，进程的地址空间为4G，包括1G的内核地址空间-----内核栈，和3G的用户地址空间-----用户栈。

内核栈，是各个进程在刚开始建立的时候通过内存映射共享的，但是每个进程拥有独立的4G的虚拟内存空间从这一点看又是独立的，互不干扰的（只是刚开始大家都是映射的同一份内存拷贝）

用户栈就是大家所熟悉的内存四区，包括：代码区、全局数据区、堆区、栈区

用户栈中的堆区、栈区即为进程堆、进程栈

进程堆、进程栈与线程栈

1.线程栈的空间开辟在所属进程的堆区与共享内存区之间，线程与其所属的进程共享进程的用户空间，所以线程栈之间可以互访。线程栈的起始地址和大小存放在pthread_attr_t 中，栈的大小并不是用来判断栈是否越界，而是用来初始化避免栈溢出的缓冲区的大小（或者说安全间隙的大小）

2.进程初始化的时候，系统会在进程的地址空间中创建一个堆，叫进程默认堆。进程中所有的线程共用这一个堆。当然，可以增加1个或几个堆，给不同的线程共同使用或单独使用。----一个进程可以多个堆

3、创建线程的时候，系统会在进程的地址空间中分配1块内存给线程栈，通常是1MB或4MB或8MB。线程栈是独立的，但是还是可以互访，因为线程共享内存空间

4.堆的分配：从操作系统角度来看，进程分配内存有两种方式，分别由两个系统调用完成：brk（）和mmap（），glibc中malloc封装了

5.线程栈位置-内存分布测试代码

[cpp] view plain copy

#include

#include

#include

#include

#include

#include

#include

void* func(void* arg)

{

long int tid = (long int)syscall(SYS_gettid);

printf("The ID of this thread is: %ldn", tid );

static int a=10;

int b=11;

int* c=(int *)malloc(sizeof(int));

printf("in thread id:%u a:%p b:%p c:%pn",tid,&a,&b,c);

printf("leave thread id:%ldn",tid);

sleep(20);

free((void *)c);

}

void main()

{

pthread_t th1,th2;

printf("pid=%un",(int)getpid());

func(NULL);

int ret=pthread_create(&th1,NULL,func,NULL);

if(ret!=0)

{

printf("thread1[%d]:%sn",th1,strerror(errno));

}

ret=pthread_create(&th2,NULL,func,NULL);

if(ret!=0)

{

printf("thread2[%d]:%sn",th2,strerror(errno));

}

pthread_join(th1,NULL);

pthread_join(th2,NULL);

}

输出：

[le@localhost threadStack]$ ./threadStack_main pid=16433

The ID of this thread is: 16433

in thread id:16433 a:0x60107c b:0x7fffc89ce7ac c:0x1b54010

leave thread id:16433

The ID of this thread is: 16461

The ID of this thread is: 16460

in thread id:16461 a:0x60107c b:0x7f6abb096efc c:0x7f6ab40008c0

leave thread id:16461

in thread id:16460 a:0x60107c b:0x7f6abb897efc c:0x7f6aac0008c0

leave thread id:16460

主线程调用func后

[le@localhost threadStack]$ sudo cat /proc/16433/maps

00400000-00401000 r-xp 00000000 fd:02 11666 /home/le/code/threadStack/threadStack_main

00600000-00601000 r--p 00000000 fd:02 11666 /home/le/code/threadStack/threadStack_main

00601000-00602000 rw-p 00001000 fd:02 11666 /home/le/code/threadStack/threadStack_main

01b54000-01b75000 rw-p 00000000 00:00 0 [heap]

7f6abb899000-7f6abba4f000 r-xp 00000000 fd:00 100678959 /usr/lib64/libc-2.17.so

7f6abba4f000-7f6abbc4f000 ---p 001b6000 fd:00 100678959 /usr/lib64/libc-2.17.so

7f6abbc4f000-7f6abbc53000 r--p 001b6000 fd:00 100678959 /usr/lib64/libc-2.17.so

7f6abbc53000-7f6abbc55000 rw-p 001ba000 fd:00 100678959 /usr/lib64/libc-2.17.so

7f6abbc55000-7f6abbc5a000 rw-p 00000000 00:00 0

7f6abbc5a000-7f6abbc70000 r-xp 00000000 fd:00 105796566 /usr/lib64/libpthread-2.17.so

7f6abbc70000-7f6abbe70000 ---p 00016000 fd:00 105796566 /usr/lib64/libpthread-2.17.so

7f6abbe70000-7f6abbe71000 r--p 00016000 fd:00 105796566 /usr/lib64/libpthread-2.17.so

7f6abbe71000-7f6abbe72000 rw-p 00017000 fd:00 105796566 /usr/lib64/libpthread-2.17.so

7f6abbe72000-7f6abbe76000 rw-p 00000000 00:00 0

7f6abbe76000-7f6abbe97000 r-xp 00000000 fd:00 105796545 /usr/lib64/ld-2.17.so

7f6abc073000-7f6abc076000 rw-p 00000000 00:00 0

7f6abc095000-7f6abc097000 rw-p 00000000 00:00 0

7f6abc097000-7f6abc098000 r--p 00021000 fd:00 105796545 /usr/lib64/ld-2.17.so

7f6abc098000-7f6abc099000 rw-p 00022000 fd:00 105796545 /usr/lib64/ld-2.17.so

7f6abc099000-7f6abc09a000 rw-p 00000000 00:00 0

7fffc89b0000-7fffc89d1000 rw-p 00000000 00:00 0 [stack]

7fffc89fe000-7fffc8a00000 r-xp 00000000 00:00 0 [vdso]

ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall]

两个子线程启动后

[le@localhost threadStack]$ sudo cat /proc/16433/maps

00400000-00401000 r-xp 00000000 fd:02 11666 /home/le/code/threadStack/threadStack_main

00600000-00601000 r--p 00000000 fd:02 11666 /home/le/code/threadStack/threadStack_main

00601000-00602000 rw-p 00001000 fd:02 11666 /home/le/code/threadStack/threadStack_main

01b54000-01b75000 rw-p 00000000 00:00 0 [heap]

7f6aac000000-7f6aac021000 rw-p 00000000 00:00 0

7f6aac021000-7f6ab0000000 ---p 00000000 00:00 0

7f6ab4000000-7f6ab4021000 rw-p 00000000 00:00 0

7f6ab4021000-7f6ab8000000 ---p 00000000 00:00 0

7f6aba897000-7f6aba898000 ---p 00000000 00:00 0

7f6aba898000-7f6abb098000 rw-p 00000000 00:00 0 [stack:16461]

7f6abb098000-7f6abb099000 ---p 00000000 00:00 0

7f6abb099000-7f6abb899000 rw-p 00000000 00:00 0 [stack:16460]

7f6abb899000-7f6abba4f000 r-xp 00000000 fd:00 100678959 /usr/lib64/libc-2.17.so

7f6abba4f000-7f6abbc4f000 ---p 001b6000 fd:00 100678959 /usr/lib64/libc-2.17.so

7f6abbc4f000-7f6abbc53000 r--p 001b6000 fd:00 100678959 /usr/lib64/libc-2.17.so

7f6abbc53000-7f6abbc55000 rw-p 001ba000 fd:00 100678959 /usr/lib64/libc-2.17.so

7f6abbc55000-7f6abbc5a000 rw-p 00000000 00:00 0

7f6abbc5a000-7f6abbc70000 r-xp 00000000 fd:00 105796566 /usr/lib64/libpthread-2.17.so

7f6abbc70000-7f6abbe70000 ---p 00016000 fd:00 105796566 /usr/lib64/libpthread-2.17.so

7f6abbe70000-7f6abbe71000 r--p 00016000 fd:00 105796566 /usr/lib64/libpthread-2.17.so

7f6abbe71000-7f