From 51a24cf6db1bab16f57841b9d67a2965fc799171 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jan=20Ko=C5=BEusznik?= <jan@kozusznik.cz>
Date: Wed, 24 Mar 2021 14:12:12 +0100
Subject: [PATCH] solution
---
.../koz01/java2/lab07/ComplicatedProcess.java | 49 ++++++++++
.../java/koz01/java2/lab07/TestThread.java | 89 +++++++++++++++++++
2 files changed, 138 insertions(+)
create mode 100644 src/test/java/koz01/java2/lab07/ComplicatedProcess.java
create mode 100644 src/test/java/koz01/java2/lab07/TestThread.java
diff --git a/src/test/java/koz01/java2/lab07/ComplicatedProcess.java b/src/test/java/koz01/java2/lab07/ComplicatedProcess.java
new file mode 100644
index 0000000..4e477d4
--- /dev/null
+++ b/src/test/java/koz01/java2/lab07/ComplicatedProcess.java
@@ -0,0 +1,49 @@
+package koz01.java2.lab07;
+
+import java.math.BigInteger;
+import java.util.Random;
+import java.util.concurrent.TimeUnit;
+import java.util.function.Consumer;
+
+import lombok.extern.log4j.Log4j2;
+
+@Log4j2
+public class ComplicatedProcess {
+
+ private Random rnd = new Random();
+
+ public void doNop(Consumer<Long> durationConsumer) {
+ long start = System.currentTimeMillis();
+ try {
+ TimeUnit.MILLISECONDS.sleep(rnd.nextInt(3001) + 2000);
+ }
+ catch (InterruptedException exc) {
+ log.error("sleep", exc);
+ }
+
+ durationConsumer.accept(System.currentTimeMillis() - start);
+ }
+
+ public Long doNopReturnDuration() {
+ long start = System.currentTimeMillis();
+ try {
+ TimeUnit.MILLISECONDS.sleep(rnd.nextInt(3001) + 2000);
+ }
+ catch (InterruptedException exc) {
+ log.error("sleep", exc);
+ }
+
+ return System.currentTimeMillis() - start;
+ }
+
+ public Long doComputeFactorial() {
+ long start = System.currentTimeMillis();
+
+ BigInteger result = BigInteger.ONE;
+ for (int i = 2; i <= 50000; i++) {
+ result = result.multiply(BigInteger.valueOf(i));
+ }
+ return System.currentTimeMillis() - start;
+ }
+
+}
diff --git a/src/test/java/koz01/java2/lab07/TestThread.java b/src/test/java/koz01/java2/lab07/TestThread.java
new file mode 100644
index 0000000..b42c32a
--- /dev/null
+++ b/src/test/java/koz01/java2/lab07/TestThread.java
@@ -0,0 +1,89 @@
+
+package koz01.java2.lab07;
+
+import java.util.Collection;
+import java.util.LinkedList;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.stream.Collectors;
+
+import org.junit.jupiter.api.Test;
+
+import lombok.extern.log4j.Log4j2;
+
+@Log4j2
+public class TestThread {
+
+ @Test
+ public void testThreads() {
+ final ComplicatedProcess cp = new ComplicatedProcess();
+ Collection<Thread> threads = new LinkedList<>();
+ Collection<Long> durations = new LinkedList<>();
+ long start = System.currentTimeMillis();
+ for (int i = 0; i < 10; i++) {
+ final int threadNu = i;
+ Thread t = new Thread() {
+
+ @Override
+ public void run() {
+ cp.doNop(l -> durations.add(l));
+ };
+ };
+ t.start();
+ threads.add(t);
+ }
+ threads.stream().forEach(t -> {
+ try {
+ t.join();
+ }
+ catch (InterruptedException exc) {
+ log.error("join", t);
+ }
+ });
+ long totalDuration = System.currentTimeMillis() - start;
+ long maxDuration = durations.stream().mapToLong(l -> l).max().getAsLong();
+ log.info("duration: {}/{} ms", maxDuration, totalDuration);
+ }
+
+ @Test
+ public void testExecutors() {
+ int threads = Runtime.getRuntime().availableProcessors();
+ ExecutorService executorService = Executors.newFixedThreadPool(threads);
+ log.info("Threads: {}", threads);
+ final ComplicatedProcess cp = new ComplicatedProcess();
+ runExecutors(executorService, cp);
+ executorService.shutdown();
+ }
+
+ private void runExecutors(ExecutorService executorService,
+ final ComplicatedProcess cp)
+ {
+
+ Collection<Future<Long>> executions = new LinkedList<>();
+ long start = System.currentTimeMillis();
+ for (int i = 0; i < 10; i++) {
+ Future<Long> execution = executorService.submit(cp::doComputeFactorial);
+ executions.add(execution);
+ }
+ Collection<Long> durations = executions.stream().map(this::getValue)
+ .collect(Collectors.toList());
+ long totalDuration = System.currentTimeMillis() - start;
+ long maxDuration = durations.stream().mapToLong(l -> l).max().getAsLong();
+ log.info("duration: {}/{} ms", maxDuration, totalDuration);
+ }
+
+ private Long getValue(Future<Long> f) {
+ {
+ try {
+ return f.get();
+ }
+ catch (InterruptedException | ExecutionException exc) {
+ log.error("get", exc);
+ return Long.valueOf(-1);
+ }
+ }
+
+ }
+}
--
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