关于pthread_cleanup_push注册的清理函数被执行的疑问

linux_c_py_php

       A cancellation clean-up handler is popped from the stack and executed in the following circumstances:

       1. When a thread is canceled, all of the stacked clean-up handlers are popped and executed in the reverse of  the
          order in which they were pushed onto the stack.

       2. When  a  thread  terminates by calling pthread_exit(3), all clean-up handlers are executed as described in the
          preceding point.  (Clean-up handlers are not called if the thread terminates by performing a return  from  the
          thread start function.)

       3. When  a  thread  calls pthread_cleanup_pop() with a nonzero execute argument, the top-most clean-up handler is
          popped and executed.     


  POSIX.1 says that the effect of using return, break, continue, or goto to prematurely  leave  a  block  bracketed
       pthread_cleanup_push() and pthread_cleanup_pop() is undefined.  Portable applications should avoid doing this.

linux_c_py_php

POSIX.1 says that the effect of using return, break, continue, or goto to prematurely  leave  a  block  bracketed
       pthread_cleanup_push() and pthread_cleanup_pop() is undefined.  Portable applications should avoid doing this.