folder moved

core-java/heapdump/README.md

@@ -0,0 +1,3 @@
+# Related Blog Posts
+
+* [How to do heap dump analysis](https://reflectoring.io/create-analyze-heapdump/)

core-java/heapdump/mvnw

@@ -0,0 +1,310 @@
+#!/bin/sh
+# ----------------------------------------------------------------------------
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you 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.
+# ----------------------------------------------------------------------------
+
+# ----------------------------------------------------------------------------
+# Maven Start Up Batch script
+#
+# Required ENV vars:
+# ------------------
+#   JAVA_HOME - location of a JDK home dir
+#
+# Optional ENV vars
+# -----------------
+#   M2_HOME - location of maven2's installed home dir
+#   MAVEN_OPTS - parameters passed to the Java VM when running Maven
+#     e.g. to debug Maven itself, use
+#       set MAVEN_OPTS=-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8000
+#   MAVEN_SKIP_RC - flag to disable loading of mavenrc files
+# ----------------------------------------------------------------------------
+
+if [ -z "$MAVEN_SKIP_RC" ] ; then
+
+  if [ -f /etc/mavenrc ] ; then
+    . /etc/mavenrc
+  fi
+
+  if [ -f "$HOME/.mavenrc" ] ; then
+    . "$HOME/.mavenrc"
+  fi
+
+fi
+
+# OS specific support.  $var _must_ be set to either true or false.
+cygwin=false;
+darwin=false;
+mingw=false
+case "`uname`" in
+  CYGWIN*) cygwin=true ;;
+  MINGW*) mingw=true;;
+  Darwin*) darwin=true
+    # Use /usr/libexec/java_home if available, otherwise fall back to /Library/Java/Home
+    # See https://developer.apple.com/library/mac/qa/qa1170/_index.html
+    if [ -z "$JAVA_HOME" ]; then
+      if [ -x "/usr/libexec/java_home" ]; then
+        export JAVA_HOME="`/usr/libexec/java_home`"
+      else
+        export JAVA_HOME="/Library/Java/Home"
+      fi
+    fi
+    ;;
+esac
+
+if [ -z "$JAVA_HOME" ] ; then
+  if [ -r /etc/gentoo-release ] ; then
+    JAVA_HOME=`java-config --jre-home`
+  fi
+fi
+
+if [ -z "$M2_HOME" ] ; then
+  ## resolve links - $0 may be a link to maven's home
+  PRG="$0"
+
+  # need this for relative symlinks
+  while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+      PRG="$link"
+    else
+      PRG="`dirname "$PRG"`/$link"
+    fi
+  done
+
+  saveddir=`pwd`
+
+  M2_HOME=`dirname "$PRG"`/..
+
+  # make it fully qualified
+  M2_HOME=`cd "$M2_HOME" && pwd`
+
+  cd "$saveddir"
+  # echo Using m2 at $M2_HOME
+fi
+
+# For Cygwin, ensure paths are in UNIX format before anything is touched
+if $cygwin ; then
+  [ -n "$M2_HOME" ] &&
+    M2_HOME=`cygpath --unix "$M2_HOME"`
+  [ -n "$JAVA_HOME" ] &&
+    JAVA_HOME=`cygpath --unix "$JAVA_HOME"`
+  [ -n "$CLASSPATH" ] &&
+    CLASSPATH=`cygpath --path --unix "$CLASSPATH"`
+fi
+
+# For Mingw, ensure paths are in UNIX format before anything is touched
+if $mingw ; then
+  [ -n "$M2_HOME" ] &&
+    M2_HOME="`(cd "$M2_HOME"; pwd)`"
+  [ -n "$JAVA_HOME" ] &&
+    JAVA_HOME="`(cd "$JAVA_HOME"; pwd)`"
+fi
+
+if [ -z "$JAVA_HOME" ]; then
+  javaExecutable="`which javac`"
+  if [ -n "$javaExecutable" ] && ! [ "`expr \"$javaExecutable\" : '\([^ ]*\)'`" = "no" ]; then
+    # readlink(1) is not available as standard on Solaris 10.
+    readLink=`which readlink`
+    if [ ! `expr "$readLink" : '\([^ ]*\)'` = "no" ]; then
+      if $darwin ; then
+        javaHome="`dirname \"$javaExecutable\"`"
+        javaExecutable="`cd \"$javaHome\" && pwd -P`/javac"
+      else
+        javaExecutable="`readlink -f \"$javaExecutable\"`"
+      fi
+      javaHome="`dirname \"$javaExecutable\"`"
+      javaHome=`expr "$javaHome" : '\(.*\)/bin'`
+      JAVA_HOME="$javaHome"
+      export JAVA_HOME
+    fi
+  fi
+fi
+
+if [ -z "$JAVACMD" ] ; then
+  if [ -n "$JAVA_HOME"  ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+      # IBM's JDK on AIX uses strange locations for the executables
+      JAVACMD="$JAVA_HOME/jre/sh/java"
+    else
+      JAVACMD="$JAVA_HOME/bin/java"
+    fi
+  else
+    JAVACMD="`which java`"
+  fi
+fi
+
+if [ ! -x "$JAVACMD" ] ; then
+  echo "Error: JAVA_HOME is not defined correctly." >&2
+  echo "  We cannot execute $JAVACMD" >&2
+  exit 1
+fi
+
+if [ -z "$JAVA_HOME" ] ; then
+  echo "Warning: JAVA_HOME environment variable is not set."
+fi
+
+CLASSWORLDS_LAUNCHER=org.codehaus.plexus.classworlds.launcher.Launcher
+
+# traverses directory structure from process work directory to filesystem root
+# first directory with .mvn subdirectory is considered project base directory
+find_maven_basedir() {
+
+  if [ -z "$1" ]
+  then
+    echo "Path not specified to find_maven_basedir"
+    return 1
+  fi
+
+  basedir="$1"
+  wdir="$1"
+  while [ "$wdir" != '/' ] ; do
+    if [ -d "$wdir"/.mvn ] ; then
+      basedir=$wdir
+      break
+    fi
+    # workaround for JBEAP-8937 (on Solaris 10/Sparc)
+    if [ -d "${wdir}" ]; then
+      wdir=`cd "$wdir/.."; pwd`
+    fi
+    # end of workaround
+  done
+  echo "${basedir}"
+}
+
+# concatenates all lines of a file
+concat_lines() {
+  if [ -f "$1" ]; then
+    echo "$(tr -s '\n' ' ' < "$1")"
+  fi
+}
+
+BASE_DIR=`find_maven_basedir "$(pwd)"`
+if [ -z "$BASE_DIR" ]; then
+  exit 1;
+fi
+
+##########################################################################################
+# Extension to allow automatically downloading the maven-wrapper.jar from Maven-central
+# This allows using the maven wrapper in projects that prohibit checking in binary data.
+##########################################################################################
+if [ -r "$BASE_DIR/.mvn/wrapper/maven-wrapper.jar" ]; then
+    if [ "$MVNW_VERBOSE" = true ]; then
+      echo "Found .mvn/wrapper/maven-wrapper.jar"
+    fi
+else
+    if [ "$MVNW_VERBOSE" = true ]; then
+      echo "Couldn't find .mvn/wrapper/maven-wrapper.jar, downloading it ..."
+    fi
+    if [ -n "$MVNW_REPOURL" ]; then
+      jarUrl="$MVNW_REPOURL/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar"
+    else
+      jarUrl="https://repo.maven.apache.org/maven2/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar"
+    fi
+    while IFS="=" read key value; do
+      case "$key" in (wrapperUrl) jarUrl="$value"; break ;;
+      esac
+    done < "$BASE_DIR/.mvn/wrapper/maven-wrapper.properties"
+    if [ "$MVNW_VERBOSE" = true ]; then
+      echo "Downloading from: $jarUrl"
+    fi
+    wrapperJarPath="$BASE_DIR/.mvn/wrapper/maven-wrapper.jar"
+    if $cygwin; then
+      wrapperJarPath=`cygpath --path --windows "$wrapperJarPath"`
+    fi
+
+    if command -v wget > /dev/null; then
+        if [ "$MVNW_VERBOSE" = true ]; then
+          echo "Found wget ... using wget"
+        fi
+        if [ -z "$MVNW_USERNAME" ] || [ -z "$MVNW_PASSWORD" ]; then
+            wget "$jarUrl" -O "$wrapperJarPath"
+        else
+            wget --http-user=$MVNW_USERNAME --http-password=$MVNW_PASSWORD "$jarUrl" -O "$wrapperJarPath"
+        fi
+    elif command -v curl > /dev/null; then
+        if [ "$MVNW_VERBOSE" = true ]; then
+          echo "Found curl ... using curl"
+        fi
+        if [ -z "$MVNW_USERNAME" ] || [ -z "$MVNW_PASSWORD" ]; then
+            curl -o "$wrapperJarPath" "$jarUrl" -f
+        else
+            curl --user $MVNW_USERNAME:$MVNW_PASSWORD -o "$wrapperJarPath" "$jarUrl" -f
+        fi
+
+    else
+        if [ "$MVNW_VERBOSE" = true ]; then
+          echo "Falling back to using Java to download"
+        fi
+        javaClass="$BASE_DIR/.mvn/wrapper/MavenWrapperDownloader.java"
+        # For Cygwin, switch paths to Windows format before running javac
+        if $cygwin; then
+          javaClass=`cygpath --path --windows "$javaClass"`
+        fi
+        if [ -e "$javaClass" ]; then
+            if [ ! -e "$BASE_DIR/.mvn/wrapper/MavenWrapperDownloader.class" ]; then
+                if [ "$MVNW_VERBOSE" = true ]; then
+                  echo " - Compiling MavenWrapperDownloader.java ..."
+                fi
+                # Compiling the Java class
+                ("$JAVA_HOME/bin/javac" "$javaClass")
+            fi
+            if [ -e "$BASE_DIR/.mvn/wrapper/MavenWrapperDownloader.class" ]; then
+                # Running the downloader
+                if [ "$MVNW_VERBOSE" = true ]; then
+                  echo " - Running MavenWrapperDownloader.java ..."
+                fi
+                ("$JAVA_HOME/bin/java" -cp .mvn/wrapper MavenWrapperDownloader "$MAVEN_PROJECTBASEDIR")
+            fi
+        fi
+    fi
+fi
+##########################################################################################
+# End of extension
+##########################################################################################
+
+export MAVEN_PROJECTBASEDIR=${MAVEN_BASEDIR:-"$BASE_DIR"}
+if [ "$MVNW_VERBOSE" = true ]; then
+  echo $MAVEN_PROJECTBASEDIR
+fi
+MAVEN_OPTS="$(concat_lines "$MAVEN_PROJECTBASEDIR/.mvn/jvm.config") $MAVEN_OPTS"
+
+# For Cygwin, switch paths to Windows format before running java
+if $cygwin; then
+  [ -n "$M2_HOME" ] &&
+    M2_HOME=`cygpath --path --windows "$M2_HOME"`
+  [ -n "$JAVA_HOME" ] &&
+    JAVA_HOME=`cygpath --path --windows "$JAVA_HOME"`
+  [ -n "$CLASSPATH" ] &&
+    CLASSPATH=`cygpath --path --windows "$CLASSPATH"`
+  [ -n "$MAVEN_PROJECTBASEDIR" ] &&
+    MAVEN_PROJECTBASEDIR=`cygpath --path --windows "$MAVEN_PROJECTBASEDIR"`
+fi
+
+# Provide a "standardized" way to retrieve the CLI args that will
+# work with both Windows and non-Windows executions.
+MAVEN_CMD_LINE_ARGS="$MAVEN_CONFIG $@"
+export MAVEN_CMD_LINE_ARGS
+
+WRAPPER_LAUNCHER=org.apache.maven.wrapper.MavenWrapperMain
+
+exec "$JAVACMD" \
+  $MAVEN_OPTS \
+  -classpath "$MAVEN_PROJECTBASEDIR/.mvn/wrapper/maven-wrapper.jar" \
+  "-Dmaven.home=${M2_HOME}" "-Dmaven.multiModuleProjectDirectory=${MAVEN_PROJECTBASEDIR}" \
+  ${WRAPPER_LAUNCHER} $MAVEN_CONFIG "$@"

core-java/heapdump/mvnw.cmd

@@ -0,0 +1,182 @@
+@REM ----------------------------------------------------------------------------
+@REM Licensed to the Apache Software Foundation (ASF) under one
+@REM or more contributor license agreements.  See the NOTICE file
+@REM distributed with this work for additional information
+@REM regarding copyright ownership.  The ASF licenses this file
+@REM to you under the Apache License, Version 2.0 (the
+@REM "License"); you may not use this file except in compliance
+@REM with the License.  You may obtain a copy of the License at
+@REM
+@REM    http://www.apache.org/licenses/LICENSE-2.0
+@REM
+@REM Unless required by applicable law or agreed to in writing,
+@REM software distributed under the License is distributed on an
+@REM "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+@REM KIND, either express or implied.  See the License for the
+@REM specific language governing permissions and limitations
+@REM under the License.
+@REM ----------------------------------------------------------------------------
+
+@REM ----------------------------------------------------------------------------
+@REM Maven Start Up Batch script
+@REM
+@REM Required ENV vars:
+@REM JAVA_HOME - location of a JDK home dir
+@REM
+@REM Optional ENV vars
+@REM M2_HOME - location of maven2's installed home dir
+@REM MAVEN_BATCH_ECHO - set to 'on' to enable the echoing of the batch commands
+@REM MAVEN_BATCH_PAUSE - set to 'on' to wait for a keystroke before ending
+@REM MAVEN_OPTS - parameters passed to the Java VM when running Maven
+@REM     e.g. to debug Maven itself, use
+@REM set MAVEN_OPTS=-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8000
+@REM MAVEN_SKIP_RC - flag to disable loading of mavenrc files
+@REM ----------------------------------------------------------------------------
+
+@REM Begin all REM lines with '@' in case MAVEN_BATCH_ECHO is 'on'
+@echo off
+@REM set title of command window
+title %0
+@REM enable echoing by setting MAVEN_BATCH_ECHO to 'on'
+@if "%MAVEN_BATCH_ECHO%" == "on"  echo %MAVEN_BATCH_ECHO%
+
+@REM set %HOME% to equivalent of $HOME
+if "%HOME%" == "" (set "HOME=%HOMEDRIVE%%HOMEPATH%")
+
+@REM Execute a user defined script before this one
+if not "%MAVEN_SKIP_RC%" == "" goto skipRcPre
+@REM check for pre script, once with legacy .bat ending and once with .cmd ending
+if exist "%HOME%\mavenrc_pre.bat" call "%HOME%\mavenrc_pre.bat"
+if exist "%HOME%\mavenrc_pre.cmd" call "%HOME%\mavenrc_pre.cmd"
+:skipRcPre
+
+@setlocal
+
+set ERROR_CODE=0
+
+@REM To isolate internal variables from possible post scripts, we use another setlocal
+@setlocal
+
+@REM ==== START VALIDATION ====
+if not "%JAVA_HOME%" == "" goto OkJHome
+
+echo.
+echo Error: JAVA_HOME not found in your environment. >&2
+echo Please set the JAVA_HOME variable in your environment to match the >&2
+echo location of your Java installation. >&2
+echo.
+goto error
+
+:OkJHome
+if exist "%JAVA_HOME%\bin\java.exe" goto init
+
+echo.
+echo Error: JAVA_HOME is set to an invalid directory. >&2
+echo JAVA_HOME = "%JAVA_HOME%" >&2
+echo Please set the JAVA_HOME variable in your environment to match the >&2
+echo location of your Java installation. >&2
+echo.
+goto error
+
+@REM ==== END VALIDATION ====
+
+:init
+
+@REM Find the project base dir, i.e. the directory that contains the folder ".mvn".
+@REM Fallback to current working directory if not found.
+
+set MAVEN_PROJECTBASEDIR=%MAVEN_BASEDIR%
+IF NOT "%MAVEN_PROJECTBASEDIR%"=="" goto endDetectBaseDir
+
+set EXEC_DIR=%CD%
+set WDIR=%EXEC_DIR%
+:findBaseDir
+IF EXIST "%WDIR%"\.mvn goto baseDirFound
+cd ..
+IF "%WDIR%"=="%CD%" goto baseDirNotFound
+set WDIR=%CD%
+goto findBaseDir
+
+:baseDirFound
+set MAVEN_PROJECTBASEDIR=%WDIR%
+cd "%EXEC_DIR%"
+goto endDetectBaseDir
+
+:baseDirNotFound
+set MAVEN_PROJECTBASEDIR=%EXEC_DIR%
+cd "%EXEC_DIR%"
+
+:endDetectBaseDir
+
+IF NOT EXIST "%MAVEN_PROJECTBASEDIR%\.mvn\jvm.config" goto endReadAdditionalConfig
+
+@setlocal EnableExtensions EnableDelayedExpansion
+for /F "usebackq delims=" %%a in ("%MAVEN_PROJECTBASEDIR%\.mvn\jvm.config") do set JVM_CONFIG_MAVEN_PROPS=!JVM_CONFIG_MAVEN_PROPS! %%a
+@endlocal & set JVM_CONFIG_MAVEN_PROPS=%JVM_CONFIG_MAVEN_PROPS%
+
+:endReadAdditionalConfig
+
+SET MAVEN_JAVA_EXE="%JAVA_HOME%\bin\java.exe"
+set WRAPPER_JAR="%MAVEN_PROJECTBASEDIR%\.mvn\wrapper\maven-wrapper.jar"
+set WRAPPER_LAUNCHER=org.apache.maven.wrapper.MavenWrapperMain
+
+set DOWNLOAD_URL="https://repo.maven.apache.org/maven2/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar"
+
+FOR /F "tokens=1,2 delims==" %%A IN ("%MAVEN_PROJECTBASEDIR%\.mvn\wrapper\maven-wrapper.properties") DO (
+    IF "%%A"=="wrapperUrl" SET DOWNLOAD_URL=%%B
+)
+
+@REM Extension to allow automatically downloading the maven-wrapper.jar from Maven-central
+@REM This allows using the maven wrapper in projects that prohibit checking in binary data.
+if exist %WRAPPER_JAR% (
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Found %WRAPPER_JAR%
+    )
+) else (
+    if not "%MVNW_REPOURL%" == "" (
+        SET DOWNLOAD_URL="%MVNW_REPOURL%/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar"
+    )
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Couldn't find %WRAPPER_JAR%, downloading it ...
+        echo Downloading from: %DOWNLOAD_URL%
+    )
+
+    powershell -Command "&{"^
+		"$webclient = new-object System.Net.WebClient;"^
+		"if (-not ([string]::IsNullOrEmpty('%MVNW_USERNAME%') -and [string]::IsNullOrEmpty('%MVNW_PASSWORD%'))) {"^
+		"$webclient.Credentials = new-object System.Net.NetworkCredential('%MVNW_USERNAME%', '%MVNW_PASSWORD%');"^
+		"}"^
+		"[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12; $webclient.DownloadFile('%DOWNLOAD_URL%', '%WRAPPER_JAR%')"^
+		"}"
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Finished downloading %WRAPPER_JAR%
+    )
+)
+@REM End of extension
+
+@REM Provide a "standardized" way to retrieve the CLI args that will
+@REM work with both Windows and non-Windows executions.
+set MAVEN_CMD_LINE_ARGS=%*
+
+%MAVEN_JAVA_EXE% %JVM_CONFIG_MAVEN_PROPS% %MAVEN_OPTS% %MAVEN_DEBUG_OPTS% -classpath %WRAPPER_JAR% "-Dmaven.multiModuleProjectDirectory=%MAVEN_PROJECTBASEDIR%" %WRAPPER_LAUNCHER% %MAVEN_CONFIG% %*
+if ERRORLEVEL 1 goto error
+goto end
+
+:error
+set ERROR_CODE=1
+
+:end
+@endlocal & set ERROR_CODE=%ERROR_CODE%
+
+if not "%MAVEN_SKIP_RC%" == "" goto skipRcPost
+@REM check for post script, once with legacy .bat ending and once with .cmd ending
+if exist "%HOME%\mavenrc_post.bat" call "%HOME%\mavenrc_post.bat"
+if exist "%HOME%\mavenrc_post.cmd" call "%HOME%\mavenrc_post.cmd"
+:skipRcPost
+
+@REM pause the script if MAVEN_BATCH_PAUSE is set to 'on'
+if "%MAVEN_BATCH_PAUSE%" == "on" pause
+
+if "%MAVEN_TERMINATE_CMD%" == "on" exit %ERROR_CODE%
+
+exit /B %ERROR_CODE%

core-java/heapdump/pom.xml

@@ -0,0 +1,32 @@
+<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<groupId>io.pratik</groupId>
+	<artifactId>oomegen</artifactId>
+	<version>0.0.1-SNAPSHOT</version>
+	<name>oomegen</name>
+	<properties>
+    <maven.compiler.source>11</maven.compiler.source>
+    <maven.compiler.target>11</maven.compiler.target>
+  </properties>
+
+	<build>
+		<plugins>
+			<plugin>
+				<artifactId>maven-assembly-plugin</artifactId>
+				<configuration>
+					<archive>
+						<manifest>
+							<mainClass>io.pratik.OOMGenerator</mainClass>
+						</manifest>
+					</archive>
+					<descriptorRefs>
+						<descriptorRef>jar-with-dependencies</descriptorRef>
+					</descriptorRefs>
+				</configuration>
+			</plugin>
+		</plugins>
+	</build>
+
+</project>

core-java/heapdump/src/main/java/io/pratik/AbstractProduct.java

@@ -0,0 +1,54 @@
+/**
+ * 
+ */
+package io.pratik;
+
+import java.util.Random;
+import java.util.UUID;
+
+/**
+ * @author Pratik Das
+ *
+ */
+public class AbstractProduct {
+
+	private String name;
+	private String id;
+	private byte[] logo;
+	private static final Random random = new Random();
+
+	public AbstractProduct() {
+		super();
+		this.id = UUID.randomUUID().toString();
+		this.logo = new byte[(5 ) * 1024 * 1024];
+	}
+
+	public String getName() {
+		return name;
+	}
+
+	public void setName(String name) {
+		this.name = name;
+	}
+
+	public String getId() {
+		return id;
+	}
+
+	public void setId(String id) {
+		this.id = id;
+	}
+
+	public byte[] getLogo() {
+		return logo;
+	}
+
+	public void setLogo(byte[] logo) {
+		this.logo = logo;
+	}
+
+	public long getSize() {
+		return JavaAgent.getObjectSize(this) + JavaAgent.getObjectSize(logo) + JavaAgent.getObjectSize(id);
+	}
+
+}

core-java/heapdump/src/main/java/io/pratik/JavaAgent.java

@@ -0,0 +1,23 @@
+/**
+ * 
+ */
+package io.pratik;
+
+import java.lang.instrument.Instrumentation;
+
+/**
+ * @author Pratik Das
+ *
+ */
+public class JavaAgent {
+    private static volatile Instrumentation instrumentation;
+    public static void premain(final String agentArgs, final Instrumentation instrumentation) {
+        JavaAgent.instrumentation = instrumentation;
+    }
+    public static long getObjectSize(final Object object) {
+        if (instrumentation == null) {
+            return -1L;
+        }
+        return instrumentation.getObjectSize(object);
+    }
+}

core-java/heapdump/src/main/java/io/pratik/OOMGenerator.java

@@ -0,0 +1,29 @@
+/**
+ * 
+ */
+package io.pratik;
+
+/**
+ * @author Pratik Das
+ *
+ */
+public class OOMGenerator {
+
+	/**
+	 * @param args
+	 * @throws Exception
+	 */
+	public static void main(String[] args) throws Exception {
+		
+		System.out.println("Max JVM memory: " + Runtime.getRuntime().maxMemory()/(1024*1024));
+		try {
+			ProductManager productManager = new ProductManager();
+			productManager.populateProducts();
+			
+		} catch (OutOfMemoryError outofMemory) {
+			System.out.println("Catching out of memory error "+ Runtime.getRuntime().freeMemory()/(1024*1024));
+			// Log the information,so that we can generate the statistics (latter on).
+			throw outofMemory;
+		}
+	}
+}

core-java/heapdump/src/main/java/io/pratik/ProductManager.java

@@ -0,0 +1,58 @@
+/**
+ * 
+ */
+package io.pratik;
+
+import io.pratik.models.BrandedProduct;
+import io.pratik.models.ElectronicGood;
+import io.pratik.models.GroceryProduct;
+import io.pratik.models.LuxuryGood;
+import io.pratik.models.ProductGroup;
+
+/**
+ * @author Pratik Das
+ *
+ */
+public class ProductManager {
+	private ProductGroup regularItems = new ProductGroup();
+
+	private ProductGroup discountedItems = new ProductGroup();
+
+	public void populateProducts() {
+
+		int dummyArraySize = 1;
+		for (int loop = 0; loop < 10; loop++) {
+			if(loop%2 == 0) {
+			  createObjects(regularItems, dummyArraySize);
+			}else {
+			  createObjects(discountedItems, dummyArraySize);
+			}
+			System.out.println("Memory Consumed till now: " + loop + "::"+ regularItems + " "+discountedItems );
+			dummyArraySize *= dummyArraySize * 2;
+		}
+	}
+
+	private void createObjects(ProductGroup productGroup, int dummyArraySize) {
+		for (int i = 0; i < dummyArraySize; ) {
+			productGroup.add(createProduct());
+		}
+ 	}
+	
+	private AbstractProduct createProduct() {
+        int randomIndex = (int) Math.round(Math.random() * 10);
+        switch (randomIndex) {
+		case 0:
+			return  new ElectronicGood();
+		case 1:
+			return	new BrandedProduct();
+		case 2:
+			return new GroceryProduct();
+		case 3:
+			return new LuxuryGood();
+		default:
+			return	new BrandedProduct();
+		}
+		
+	}
+
+}

core-java/heapdump/src/main/java/io/pratik/models/BrandedProduct.java

@@ -0,0 +1,48 @@
+/**
+ * 
+ */
+package io.pratik.models;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import io.pratik.AbstractProduct;
+import io.pratik.JavaAgent;
+
+/**
+ * @author Pratik Das
+ *
+ */
+public class BrandedProduct extends AbstractProduct{
+	private String brandName;
+	private Price mrp;
+	
+	
+
+	public BrandedProduct() {
+		super();
+		mrp = new Price();
+
+	}
+
+	public Price getMrp() {
+		return mrp;
+	}
+
+	public void setMrp(Price mrp) {
+		this.mrp = mrp;
+	}
+
+	public String getBrandName() {
+		return brandName;
+	}
+
+	public void setBrandName(String brandName) {
+		this.brandName = brandName;
+	}
+	
+	public long getSize() {
+		return JavaAgent.getObjectSize(this) + JavaAgent.getObjectSize(brandName);
+	}
+    
+}

core-java/heapdump/src/main/java/io/pratik/models/ElectronicGood.java

@@ -0,0 +1,31 @@
+/**
+ * 
+ */
+package io.pratik.models;
+
+import io.pratik.AbstractProduct;
+
+/**
+ * @author Pratik Das
+ *
+ */
+public class ElectronicGood extends AbstractProduct{
+	
+	private Manufacturer manufacturer;
+	
+	
+
+	public ElectronicGood() {
+		super();
+		this.manufacturer = new Manufacturer();
+	}
+
+	public Manufacturer getManufacturer() {
+		return manufacturer;
+	}
+
+	public void setManufacturer(Manufacturer manufacturer) {
+		this.manufacturer = manufacturer;
+	}
+	
+}

core-java/heapdump/src/main/java/io/pratik/models/GroceryProduct.java

@@ -0,0 +1,35 @@
+/**
+ * 
+ */
+package io.pratik.models;
+
+import io.pratik.AbstractProduct;
+
+/**
+ * @author Pratik Das
+ *
+ */
+public class GroceryProduct extends AbstractProduct{
+	private Price mrp;
+	private Price discountedPrice;
+	
+	
+	public GroceryProduct() {
+		super();
+		mrp = new Price();
+		discountedPrice = new Price();
+	}
+	public Price getMrp() {
+		return mrp;
+	}
+	public void setMrp(Price mrp) {
+		this.mrp = mrp;
+	}
+	public Price getDiscountedPrice() {
+		return discountedPrice;
+	}
+	public void setDiscountedPrice(Price discountedPrice) {
+		this.discountedPrice = discountedPrice;
+	}
+
+}

core-java/heapdump/src/main/java/io/pratik/models/LuxuryGood.java

@@ -0,0 +1,25 @@
+/**
+ * 
+ */
+package io.pratik.models;
+
+import io.pratik.AbstractProduct;
+
+/**
+ * @author Pratik Das
+ *
+ */
+public class LuxuryGood extends AbstractProduct{
+	private String luxuryCategory;
+
+	public String getLuxuryCategory() {
+		return luxuryCategory;
+	}
+
+	public void setLuxuryCategory(String luxuryCategory) {
+		this.luxuryCategory = luxuryCategory;
+	}
+	
+	
+
+}

core-java/heapdump/src/main/java/io/pratik/models/Manufacturer.java

@@ -0,0 +1,43 @@
+/**
+ * 
+ */
+package io.pratik.models;
+
+import io.pratik.JavaAgent;
+
+/**
+ * @author Pratik Das
+ *
+ */
+public class Manufacturer {
+	
+	private String name;
+	private String address;
+	
+	
+	public Manufacturer() {
+		super();
+		this.name = "Dummy";
+		this.address = "dummy state";
+	}
+	public String getName() {
+		return name;
+	}
+	public void setName(String name) {
+		this.name = name;
+	}
+	public String getAddress() {
+		return address;
+	}
+	public void setAddress(String address) {
+		this.address = address;
+	}
+	
+	public long getSize() {
+		return JavaAgent.getObjectSize(this) 
+				+ JavaAgent.getObjectSize(name) 
+				+ JavaAgent.getObjectSize(address);
+	}
+	
+
+}

core-java/heapdump/src/main/java/io/pratik/models/Price.java

@@ -0,0 +1,45 @@
+/**
+ * 
+ */
+package io.pratik.models;
+
+import java.util.Date;
+
+import io.pratik.JavaAgent;
+
+/**
+ * @author Pratik Das
+ *
+ */
+public final class Price {
+	
+	private Double value;
+	private Date lastUpdated;
+	
+	
+	public Price() {
+		super();
+		value = 48.0;
+		lastUpdated = new Date();
+		
+	}
+	public Double getValue() {
+		return value;
+	}
+	public void setValue(Double value) {
+		this.value = value;
+	}
+	public Date getLastUpdated() {
+		return lastUpdated;
+	}
+	public void setLastUpdated(Date lastUpdated) {
+		this.lastUpdated = lastUpdated;
+	}
+	
+	public long getSize() {
+		return JavaAgent.getObjectSize(this) 
+				+ JavaAgent.getObjectSize(value) 
+				+ JavaAgent.getObjectSize(lastUpdated.toString());
+	}
+
+}

core-java/heapdump/src/main/java/io/pratik/models/ProductGroup.java

@@ -0,0 +1,22 @@
+/**
+ * 
+ */
+package io.pratik.models;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import io.pratik.AbstractProduct;
+
+/**
+ * @author Pratik Das
+ *
+ */
+public class ProductGroup {
+	
+	private List<AbstractProduct> products = new ArrayList<AbstractProduct>();
+	
+	public void add(AbstractProduct product) {
+		products.add(product);
+	}
+}

core-java/heapdump/src/main/resources/META-INF/MANIFEST.MF

@@ -0,0 +1,2 @@
+Manifest-Version: 1.0
+Premain-Class: io.pratik.JavaAgent

core-java/heapdump/target/classes/META-INF/MANIFEST.MF

@@ -0,0 +1,2 @@
+Manifest-Version: 1.0
+Premain-Class: io.pratik.JavaAgent

core-java/heapdump/target/maven-archiver/pom.properties

@@ -0,0 +1,5 @@
+#Generated by Maven
+#Fri Feb 12 23:56:04 IST 2021
+groupId=io.pratik
+artifactId=oomegen
+version=0.0.1-SNAPSHOT

core-java/heapdump/target/maven-status/maven-compiler-plugin/compile/default-compile/createdFiles.lst

@@ -0,0 +1,11 @@
+io/pratik/ProductManager.class
+io/pratik/models/Price.class
+io/pratik/models/ProductGroup.class
+io/pratik/models/LuxuryGood.class
+io/pratik/JavaAgent.class
+io/pratik/models/ElectronicGood.class
+io/pratik/models/BrandedProduct.class
+io/pratik/models/Manufacturer.class
+io/pratik/AbstractProduct.class
+io/pratik/models/GroceryProduct.class
+io/pratik/OOMGenerator.class

core-java/heapdump/target/maven-status/maven-compiler-plugin/compile/default-compile/inputFiles.lst

@@ -0,0 +1,11 @@
+/Users/fab/Documents/pratik/code-examples/heapdump/src/main/java/io/pratik/models/LuxuryGood.java
+/Users/fab/Documents/pratik/code-examples/heapdump/src/main/java/io/pratik/AbstractProduct.java
+/Users/fab/Documents/pratik/code-examples/heapdump/src/main/java/io/pratik/models/Price.java
+/Users/fab/Documents/pratik/code-examples/heapdump/src/main/java/io/pratik/ProductManager.java
+/Users/fab/Documents/pratik/code-examples/heapdump/src/main/java/io/pratik/JavaAgent.java
+/Users/fab/Documents/pratik/code-examples/heapdump/src/main/java/io/pratik/models/BrandedProduct.java
+/Users/fab/Documents/pratik/code-examples/heapdump/src/main/java/io/pratik/models/GroceryProduct.java
+/Users/fab/Documents/pratik/code-examples/heapdump/src/main/java/io/pratik/models/ProductGroup.java
+/Users/fab/Documents/pratik/code-examples/heapdump/src/main/java/io/pratik/OOMGenerator.java
+/Users/fab/Documents/pratik/code-examples/heapdump/src/main/java/io/pratik/models/ElectronicGood.java
+/Users/fab/Documents/pratik/code-examples/heapdump/src/main/java/io/pratik/models/Manufacturer.java