problem well before the due date$).$

Consider the following test program for an implementation of KThread.join in Nachos. It begins when the main Nachos thread calls KThread. selfTest. You do not need to know the details of how join is parent is placed on the ready queue$)$; $(2)$ if the child has finished, the parent continues to execute without blocking. Assume join uses a wait queue of some kind in its implementation.

$```$

private static class A implements Runnable $\{$

A $()\{\}$

public void run $()\{$

KThread t$2=$ new KThread $($new B$()).$setName $("$B$")$;

System.out.println $("$foo$")$;

t$2.$fork $()$;

System.out.println $("$far$")$;

t$2.$join $()$;

System.out.println $("$fum$")$;

$\}$

$\}$

private static class B implements Runnable $\{$

B $()\{\}$

public void run $()\{$

System.out.println $("$fie$")$;

$\}$

$\}$

public static void selfTest$()\{$

KThread t$1=$ new KThread $($new A$()).$setName $("$A$")$;

System.out.println $("$fee$")$;

t$1.$fork $()$;

System.out.println $("$foe$")$;

t$1.$join $()$;

System.out.println $("$fun$")$;

$\}$

$```$

is on a queue.

a$.$ Context switches: main $\backslash (\backslash$rightarrow $\backslash )$

b$.$ Output:

c$.$ Thread queues when selfTest returns:

currentThread:

readyQueue:

join wait queue: to check your answer.$]$