Consider the fork_example.c code (under "Example code for processes" on Canvas). How many processes and threads are created? (code also shown below) #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <string.h> #include <errno.h> #include <inttypes.h> /* for PRIxPTR */ #include <pthread.h> // On Linux we need these for waitpid() #include <sys/types.h> #include <sys/wait.h> // On Solaris, this cleans up format warnings from GCC #define PID (int) getpid() // process identity, for output only char *me = "parent"; // or, "child" /* function prototype for thread creation */ void * thread_func(void * arg); /* data for threads */ struct thread_struct { pthread_t tid; // system-assigned thread identifier int num; // our own thread number int in; // input data int out; // output data }; struct thread_struct bogus = { 0, 0, 0, -1 }; pthread_attr_t attr; // thread attributes, not used here struct thread_struct in[2]; void thread_generator(int low, int high, char *identifier) { for (int i = low; i < high; i++) { in[i].tid = (pthread_t) (-1); // assigned later in[i].num = i; in[i].in = i+1; in[i].out = -1; printf("[pid %d] %s %s: pthread_create(%d): tryingn", PID, me, identifier, in[i].num); // pthread_create(&in[i].tid, &attr, thread_func, &in[i]); int ret = pthread_create(&in[i].tid, NULL, thread_func, &in[i]); // in[i].tid = identifier of new thread // the new thread executes thread_func(&in[i]) // pthread_create() returns an int, equal to 0 or error number if (ret == 0) { printf("[pid %d] %s %s: pthread_create(%d): okn", PID, me, identifier, in[i].num); } else { printf("[pid %d] %s %s: pthread_create(%d): failed: %sn", PID, me, identifier, in[i].num, strerror(ret)); } } } void thread_collector(int low, int high, char *identifier) { for (int i = low; i < high; i++) { printf("[pid %d] %s %s: pthread_join(%d): tryingn", PID, me, identifier, in[i].num); void *out = &bogus; int ret = pthread_join(in[i].tid, &out); // out = exit status from pthread_exit() // pthread_join() returns an int, equal to 0 or error number if (ret == 0) { printf("[pid %d] %s %s: pthread_join(%d): ok, exit status = %p, out = %dn", PID, me, identifier, in[i].num, out, in[i].out); } else { printf("[pid %d] %s %s: pthread_join(%d): failed: %s, exit status = %p, out = %dn", PID, me, identifier, in[i].num, strerror(ret), out, in[i].out); } } } int main(int argc, char * argv[]) { printf("[pid %d] %s: &bogus = %pn", PID, me, &bogus); for (int i = 0; i < 2; i++) { printf("[pid %d] %s: &in[%d] = %pn", PID, me, i, &in[i]); } for (int i = 0; i < 2; i++) { in[i].tid = (pthread_t) (-1); // assigned later in[i].num = i; in[i].in = -1; in[i].out = -1; } // create two threads thread_generator(0, 2, "main pre-fork"); pid_t pid = fork(); if (pid < 0) { printf("[pid %d] %s: main, fork(): failed: %sn", PID, me, strerror(errno)); } else if (pid == 0) { me = "child"; printf("[pid %d] %s: main, parent is %dn", PID, me, (int) getppid()); } else { printf("[pid %d] %s: main, child is %dn", P.

1. Consider the fork_example.c code (under "Example code for processes" on Canvas). How many
processes and threads are created?
(code also shown below)
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <inttypes.h> /* for PRIxPTR */
#include <pthread.h>
// On Linux we need these for waitpid()
#include <sys/types.h>
#include <sys/wait.h>
// On Solaris, this cleans up format warnings from GCC
#define PID (int) getpid()
// process identity, for output only
char *me = "parent"; // or, "child"
/* function prototype for thread creation */
void * thread_func(void * arg);
/* data for threads */
struct thread_struct {
pthread_t tid; // system-assigned thread identifier
int num; // our own thread number
int in; // input data
int out; // output data
};
struct thread_struct bogus = { 0, 0, 0, -1 };
pthread_attr_t attr; // thread attributes, not used here
struct thread_struct in[2];
void thread_generator(int low, int high, char *identifier)
{
for (int i = low; i < high; i++)
{
in[i].tid = (pthread_t) (-1); // assigned later
in[i].num = i;
in[i].in = i+1;
in[i].out = -1;
printf("[pid %d] %s %s: pthread_create(%d): tryingn",
PID, me, identifier, in[i].num);
// pthread_create(&in[i].tid, &attr, thread_func, &in[i]);
int ret = pthread_create(&in[i].tid, NULL, thread_func, &in[i]);

2. // in[i].tid = identifier of new thread
// the new thread executes thread_func(&in[i])
// pthread_create() returns an int, equal to 0 or error number
if (ret == 0)
{
printf("[pid %d] %s %s: pthread_create(%d): okn",
PID, me, identifier, in[i].num);
}
else
{
printf("[pid %d] %s %s: pthread_create(%d): failed: %sn",
PID, me, identifier, in[i].num, strerror(ret));
}
}
}
void thread_collector(int low, int high, char *identifier)
{
for (int i = low; i < high; i++)
{
printf("[pid %d] %s %s: pthread_join(%d): tryingn",
PID, me, identifier, in[i].num);
void *out = &bogus;
int ret = pthread_join(in[i].tid, &out);
// out = exit status from pthread_exit()
// pthread_join() returns an int, equal to 0 or error number
if (ret == 0)
{
printf("[pid %d] %s %s: pthread_join(%d): ok, exit status = %p, out = %dn",
PID, me, identifier, in[i].num, out, in[i].out);
}
else
{
printf("[pid %d] %s %s: pthread_join(%d): failed: %s, exit status = %p, out = %dn",
PID, me, identifier, in[i].num, strerror(ret), out, in[i].out);
}
}
}
int main(int argc, char * argv[])
{
printf("[pid %d] %s: &bogus = %pn", PID, me, &bogus);
for (int i = 0; i < 2; i++)
{ printf("[pid %d] %s: &in[%d] = %pn", PID, me, i, &in[i]); }

3. for (int i = 0; i < 2; i++)
{
in[i].tid = (pthread_t) (-1); // assigned later
in[i].num = i;
in[i].in = -1;
in[i].out = -1;
}
// create two threads
thread_generator(0, 2, "main pre-fork");
pid_t pid = fork();
if (pid < 0)
{
printf("[pid %d] %s: main, fork(): failed: %sn",
PID, me, strerror(errno));
}
else if (pid == 0)
{
me = "child";
printf("[pid %d] %s: main, parent is %dn",
PID, me, (int) getppid());
}
else
{
printf("[pid %d] %s: main, child is %dn",
PID, me, (int) pid);
}
for (int i = 0; i < 2; i++)
{ printf("[pid %d] %s: in[%d].tid = %" PRIxPTR "n", PID, me, i, (uintptr_t) in[i].tid); }
// join with two threads
thread_collector(0, 2, "main");
if (pid == 0)
{
printf("[pid %d] %s: main, sleeping 1n", PID, me);
sleep(1);
printf("[pid %d] %s: main, exitingn", PID, me);
exit(0);
}
if (pid > 0)
{
printf("[pid %d] %s: main, waitingn", PID, me);
waitpid(pid, NULL, 0);
}

4. printf("[pid %d] %s: main, exitingn", PID, me);
return 0;
}
/* standard format for Pthreads */
void * thread_func(void * arg)
{
struct thread_struct *p = arg;
printf("[pid %d] %s: hello, world, this is thread %d, ID %" PRIxPTR " %" PRIxPTR "n",
PID, me, p->num, (uintptr_t) p->tid, (uintptr_t) pthread_self());
printf("[pid %d] %s: thread %d, sleeping %dn",
PID, me, p->num, p->in);
sleep(p->in);
// do some work, so we can see if the thread actually ran
p->out = 1;
printf("[pid %d] %s: thread %d, exitingn",
PID, me, p->num);
pthread_exit(arg); // the thread's exit status
// void return
}
Group of answer choices
2 process, 2 threads
3 processes, 2 threads
2 processes, 4 threads
3 processes, 4 threads