Linux线程和进程

Question

I have a simple question about Linux threads and processes.

The process in Linux has a separate virtual address space which consists of

- stack
- heap
- bss
- code/text
- data

A process can have 'n' threads inside them.I understand that they do share the address space of the process.However since the function calls that are executed by different threads can be different, does a thread have a separate stack segment.?

Answer 1

1. Threads share the all the memory segments, including the stack segment.
2. Each thread has a separate stack.

Both are true. I know they sounds like contradiction.

The first thread's stack uses the so called "stack segment". It's allocated by the kernel.

# cat /proc/self/maps
...
7fffbe0b0000-7fffbe0d1000 rw-p 00000000 00:00 0                          [stack]
...

Threads created later (eg created by pthread_create() or clone(CLONE_VM)) use heap (or private anonymous mmap which is the same as heap in every ways) as their stack. It's allocated by the user program and passed to clone().

In short, each thread uses a separate stack. All the threads can read/write every other threads' stack.

Answer 2

是的，在POSIX线程模型下，每个线程都有自己的堆栈。