CS $4120$ Homework $2$ Points: $25$

Problem $1-$ Exercise $32\mathrm{.}4(8$ points$)$

$($Synchronized threads$)$ Write a program that launches $1000$ threads by using a fixed thread

pool. Each thread adds $1$ to a variable sum that is initially $0.$ You need to pass sum by reference

to each thread. sum is declared global to the program as is type Integers$--$ In order to pass it by

reference, define an Integer wrapper object to hold sum. Run the program with and without

synchronization to see its effect.

Problem $2-$ Exercise $32\mathrm{.}13(8$ points$)$

$($Generic parallel merge sort$)$ Revise Listing $32\mathrm{.}10$ ParallelMergeSort.java, to define a generic

parallelMergeSort method as follows:

public static $>$ void

parallelMergeSort$($E$[]$ list$)$

Create a main$()$ method which will create an array of integers, print the array of integers, then

use the parallelMergeSort$()$ on the array, and print the sorted array. Then, repeat the steps for

an array of strings.

Hints:

$1.$ Change sortTask signature to

private static class SortTask$>$ extends RecursiveAction $\{$

$2.$ This line in ParallelMax

int$[]$ firstHalf $=$ new int$[$list$.$length $/2]$;

will change to E$[]$ firstHalf $=($E$[])($new Comparable$[$list$.$length $/2])$;

and similarly for secondHalf$.$