Add sample application to show thread leaks

pom.xml

@@ -48,8 +48,9 @@
         <module>hotmethods</module>
         <module>latencies</module>
         <module>allocations</module>
-        <module>memoryleak</module>
         <module>deadlock</module>
+        <module>memoryleak</module>
+        <module>threadleak</module>
     </modules>
 
     <dependencyManagement>
@@ -64,6 +65,11 @@
                 <artifactId>base</artifactId>
                 <version>${samples.version}</version>
             </dependency>
+            <dependency>
+                <groupId>org.hdrhistogram</groupId>
+                <artifactId>HdrHistogram</artifactId>
+                <version>${hdrhistogram.version}</version>
+            </dependency>
         </dependencies>
     </dependencyManagement>
 
@@ -144,5 +150,6 @@
         <javac.target>1.8</javac.target>
         <samples.version>0.0.2-SNAPSHOT</samples.version>
         <jcommander.version>1.72</jcommander.version>
+        <hdrhistogram.version>2.1.10</hdrhistogram.version>
     </properties>
 </project>

threadleak/README.md

@@ -0,0 +1,31 @@
+Sample to show thread leaks in a Java Application
+=================================================
+
+This sample application implements merge sort algorithm using multiple threads.
+
+The algorithm for parallel merge sort was taken from the [Merge Sort example available online from the University
+of Washington](https://courses.cs.washington.edu/courses/cse373/13wi/lectures/03-13/MergeSort.java)
+
+The original example uses threads directly. This sample application uses an `ExecutorService` to run threads.
+
+This application runs continuously and prints an interval summary statistics of algorithm run time for multiple random
+number arrays. The application will also print final summary statistics of algorithm run time at the program exit.
+
+### How to run
+
+The application will throw Out of Memory error after some time when you run following command
+
+`java -Xmx1g -XX:+UnlockDiagnosticVMOptions -XX:+DebugNonSafepoints
+ -XX:+UnlockCommercialFeatures -XX:+FlightRecorder
+ -XX:StartFlightRecording=settings=profile,duration=2m,name=ThreadLeak,filename=threadleak.jfr
+ -XX:FlightRecorderOptions=loglevel=info
+ -jar target/threadleak.jar`
+
+### Analyzing Java Flight Recording
+
+In Threads -> Overview tab, you should see thread count is increasing steadily.
+
+### How to fix the Thread Leak
+
+Run the application with `--stop-leakage` parameter, which will use a single `ExecutorService` throughout the
+application.

threadleak/pom.xml

@@ -0,0 +1,51 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+    # Copyright 2018 M. Isuru Tharanga Chrishantha Perera
+    #
+    # Licensed under the Apache License, Version 2.0 (the "License");
+    # you may not use this file except in compliance with the License.
+    # You may obtain a copy of the License at
+    #
+    # http://www.apache.org/licenses/LICENSE-2.0
+    #
+    # Unless required by applicable law or agreed to in writing, software
+    # distributed under the License is distributed on an "AS IS" BASIS,
+    # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+    # See the License for the specific language governing permissions and
+    # limitations under the License.
+-->
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+
+    <parent>
+        <groupId>com.github.chrishantha.sample</groupId>
+        <artifactId>java-samples</artifactId>
+        <version>0.0.2-SNAPSHOT</version>
+        <relativePath>../pom.xml</relativePath>
+    </parent>
+
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>threadleak</artifactId>
+    <packaging>jar</packaging>
+    <name>threadleak</name>
+
+    <dependencies>
+        <dependency>
+            <groupId>com.github.chrishantha.sample</groupId>
+            <artifactId>base</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.hdrhistogram</groupId>
+            <artifactId>HdrHistogram</artifactId>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-shade-plugin</artifactId>
+            </plugin>
+        </plugins>
+    </build>
+</project>