告诉面试官这完全取决于操作系统的实现。

以Windows x86为例。只有两个段[1]，代码和数据。它们都被映射到整个2GB(线性，用户)地址空间。基础= 0,限制= 2 gb。他们本来可以做一个，但x86不允许一个段同时读/写和执行。所以他们做了两个，并设置CS指向代码描述符，其余(DS, ES, SS等)指向另一个[2]。但两者都指向同样的东西!

面试你的人做了一个隐藏的假设，他/她没有说出来，这是一个愚蠢的伎俩。

所以关于

问:告诉我是哪个线段 分享吗?

细分市场与问题无关，至少在Windows上是这样。线程共享整个地址空间。只有一个堆栈段SS，它指向DS ES CS做的完全一样的东西[2]。比如整个用户空间。0-2GB。当然，这并不意味着线程只有一个堆栈。当然，每个都有自己的堆栈，但x86段并不用于此目的。

也许*nix做一些不同的事情。谁知道呢。这个问题的前提被打破了。

至少对于用户空间是这样的。 从ntsd记事本:cs=001b ss=0023 ds=0023 es=0023

Besides global memory, threads also share a number of other attributes (i.e., these attributes are global to a process, rather than specific to a thread). These attributes include the following: process ID and parent process ID; process group ID and session ID; controlling terminal; process credentials (user and group IDs); open file descriptors; record locks created using fcntl(); signal dispositions; file system–related information: umask, current working directory, and root directory; interval timers (setitimer()) and POSIX timers (timer_create()); System V semaphore undo (semadj) values (Section 47.8); resource limits; CPU time consumed (as returned by times()); resources consumed (as returned by getrusage()); and nice value (set by setpriority() and nice()). Among the attributes that are distinct for each thread are the following: thread ID (Section 29.5); signal mask; thread-specific data (Section 31.3); alternate signal stack (sigaltstack()); the errno variable; floating-point environment (see fenv(3)); realtime scheduling policy and priority (Sections 35.2 and 35.3); CPU affinity (Linux-specific, described in Section 35.4); capabilities (Linux-specific, described in Chapter 39); and stack (local variables and function call linkage information).

摘自:《Linux编程接口:Linux和UNIX系统编程手册》，Michael Kerrisk，第619页

线程共享堆(有一个关于线程特定堆的研究)，但当前的实现共享堆。(当然还有代码)

线程共享代码、数据段和堆，但不共享堆栈。

In an x86 framework, one can divide as many segments (up to 2^16-1). The ASM directives SEGMENT/ENDS allows this, and the operators SEG and OFFSET allows initialization of segment registers. CS:IP are usually initialized by the loader, but for DS, ES, SS the application is responsible with initialization. Many environments allow the so-called "simplified segment definitions" like .code, .data, .bss, .stack etc. and, depending also on the "memory model" (small, large, compact etc.) the loader initializes segment registers accordingly. Usually .data, .bss, .stack and other usual segments (I haven't done this since 20 years so I don't remember all) are grouped in one single group - that is why usually DS, ES and SS points to teh same area, but this is only to simplify things.

一般来说，所有段寄存器在运行时都可以有不同的值。 所以，面试的问题是正确的:CODE、DATA和STACK中的哪一个在线程之间共享。堆管理是另一回事——它只是对操作系统的一系列调用。但是如果你根本没有操作系统，比如在嵌入式系统中，你还能在你的代码中新建/删除吗?

我给年轻人的建议是——读一些好的汇编编程书。似乎大学的课程在这方面相当贫乏。

您说得很对，但是线程共享除堆栈之外的所有段。线程有独立的调用堆栈，但是其他线程堆栈中的内存仍然是可访问的，理论上你可以在其他线程的本地堆栈框架中保存内存指针(尽管你可能应该找到一个更好的地方来放置内存!)。