在Linux中gettimeofday函数线程是否安全？

Question

必须全局存储当前时间才能使gettimeofday正常工作，但我不确定该函数是否修改了任何全局状态，以便并发执行未定义。

Answer 1

gettimeofday is thread safe.

The (posix) functions listed here might not be, gettimeofday is not one of them.

Answer 2

Yes, it is thread-safe. The only data it modifies is in the structures you pass pointers to, so an implementation that wasn't thread-safe would have to be doing something spooky.

Best of luck on your project.

Answer 3

In glibc the gettimeofday(2) is a simple wrapper around a system call (it's a vsyscall actually). No data is touched in the userland. It is thread-safe.

Answer 4

No data is modified with this call. You just get a copy. Hence its completely thread safe.