$1/*$ WARNING: This code is buggy! $*/$

$2$ #include "csapp.h$"$

$3$ void $*$thread$($void $*$vargp$)$;

$4$

$5$ int main$()$

$6\{$

$7$ pthread$\_$t tid;

$8$

$9$ pthread$\_$create$($&tid, NULL, thread, NULL$)$;

$10$ exit$(0)$;

$11\}$

$12$

$13/*$ Thread routine $*/$

$14$ void $*$thread$($void $*$vargp$)$

$15\{$

$16$ sleep$(1)$;

$17$ printf$("$Hello$,$ world!

$")$;

$18$ return NULL;

$19\}$

$-----------------------------------$code$/$conc$/$hellobug$.$c

Wondering if my answers for A and B are correct.

A$.$ The program in Figure $12\mathrm{.}46$ has a bug. The thread is supposed to sleep for

$1$ second and then print a string. However, when we run it on our system,

nothing prints. Why?

My answer: There$$s a bug because the $$Exit$(0)$;$$ function in line $10$ terminates the whole process, including all threads, before the thread gets a chance to run.

B$.$ You can fix this bug by replacing the exit function in line $10$ with one of two

different Pthreads function calls. Which ones?

My answer: You fix this by replacing $$Exit$(0)$;$$ with $$pthread$\_$exit$($NULL$)$;$$ or with $$pthread$\_$join$($tid$,$ NULL$)$;$$