Wrote tests to compare the read time of files vs number of cpu threads used.

multiThreadedFileIO/DataCreator.java

@@ -0,0 +1,71 @@
+import java.io.BufferedWriter;
+import java.io.File;
+import java.io.FileWriter;
+import java.math.*;
+
+/**
+ * Simple class to generate random data for
+ * file IO tests.
+ *
+ * @author Jeffery Russell 1-31-19
+ */
+public class DataCreator
+{
+    /**
+     * Generates an obscure random character
+     * @return
+     */
+    private static char rndChar()
+    {
+        // or use Random or whatever
+        int rnd = (int) (Math.random() * 52);
+        char base = (rnd < 26) ? 'A' : 'a';
+        return (char) (base + rnd % 26);
+    }
+
+
+    /**
+     * Simple function to save contents to the disk
+     *
+     * @param s
+     * @param fileName
+     */
+    private static void saveToDisk(String s, String fileName)
+    {
+        BufferedWriter writer;
+        try
+        {
+            File file = new File(fileName);
+            file.createNewFile();
+            writer = new BufferedWriter(new FileWriter(file));
+            writer.write(s);
+            writer.flush();
+            writer.close();
+        }
+        catch (Exception e)
+        {
+            e.printStackTrace();
+        }
+    }
+
+
+    /**
+     * Creates 5MB of random test data to use
+     */
+    public static void main(String[] arguments)
+    {
+        System.out.println("Creating Test Files");
+        for(int i = 0; i < 100; i++)
+        {
+            //10k random characters for each file
+            //each file is 10kb * 500 files, total size of 5MB
+            String s = "";
+            for(int j = 0; j < 1000000; j++)
+            {
+                s = s + rndChar();
+            }
+            saveToDisk(s, "./testData/" + i + ".txt");
+            System.out.println(s);
+        }
+    }
+}

multiThreadedFileIO/MultiThreadedFileReadTest.java

@@ -0,0 +1,40 @@
+import java.util.*;
+
+/**
+ * File to test the performance of multi threaded file
+ * io by reading a large quantity of files in parallel
+ * using a different amount of threads.
+ *
+ * @author Jeffery Russell 1-31-19
+ */
+public class MultiThreadedFileReadTest
+{
+    public static void main(String[] args)
+    {
+        List<Integer> x = new ArrayList<>();
+        List<Double> y = new ArrayList<>();
+        for(int i = 1; i <= 64; i++)
+        {
+            long threadTotal = 0;
+            for(int w = 0; w < 20; w++)
+            {
+                TaskManager boss = new TaskManager(i);
+
+                for(int j = 0; j < 500; j++)
+                {
+                    boss.addTask(new ReadTask("./testData/" + i + ".txt"));
+                }
+                long startTime = System.nanoTime();
+                boss.runTasks();
+                long endTime = System.nanoTime();
+                long durationMS = (endTime - startTime)/1000000;
+                threadTotal+= durationMS;
+            }
+
+            x.add(i);
+            y.add(threadTotal/20.0); //finds average
+        }
+        System.out.println(x);
+        System.out.println(y);
+    }
+}

multiThreadedFileIO/TaskManager.java

@@ -44,18 +44,29 @@ public class TaskManager
 
         Thread[] runners = new Thread[desiredThreads];
 
-        System.out.println("Total Tasks: " + tasks.size());
-        System.out.println("Threads Used:" + desiredThreads);
-
-
         for(int i = 0; i < desiredThreads; i++)
         {
             runners[i] = new Thread(()->
             {
-                while(!tasks.isEmpty())
+                ReadTask t = null;
+                while(true)
                 {
-                    ReadTask t = tasks.remove(0);
-                    t.runTask();
+                    //need synchronized block to prevent
+                    //race condition
+                    synchronized (tasks)
+                    {
+                        if(!tasks.isEmpty())
+                            t = tasks.remove(0);
+                    }
+                    if(t == null)
+                    {
+                        break;
+                    }
+                    else
+                    {
+                        t.runTask();
+                        t = null;
+                    }
                 }
             });
             runners[i].start();

multiThreadedFileIO/graph.py

@@ -0,0 +1,13 @@
+import matplotlib.pyplot as plt
+
+
+xList = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64]
+yList = [230.5, 124.0, 84.65, 63.9, 51.6, 44.2, 39.15, 34.9, 31.9, 28.7, 27.2, 25.05, 24.25, 22.8, 21.25, 20.45, 19.8, 19.4, 18.6, 17.45, 17.0, 16.95, 16.4, 24.15, 15.2, 15.2, 15.0, 14.3, 14.7, 14.65, 14.65, 14.75, 13.85, 15.1, 14.35, 35.75, 15.3, 14.45, 14.25, 13.65, 14.45, 14.6, 13.95, 14.65, 14.5, 14.3, 14.85, 14.15, 15.0, 16.25, 14.25, 14.4, 14.15, 14.45, 14.25, 14.85, 14.3, 14.35, 15.35, 13.6, 14.3, 14.2, 14.3, 13.95]
+
+
+
+plt.plot(xList, yList)
+plt.xlabel('Number of Threads')
+plt.ylabel('Execution Time (MS)')
+
+plt.show()