#BAEL-4654 (#10450)

* #BAEL-4654

* Fixing PR comments.

docker/heap-sizing/Dockerfile

@@ -0,0 +1,4 @@
+FROM openjdk:8u92-jdk-alpine
+COPY /src /src/
+RUN mkdir /app && ls /src && javac /src/main/java/com/baeldung/docker/heapsizing/PrintXmxXms.java -d /app
+CMD java -version && java $JAVA_OPTS -cp /app com.baeldung.docker.heapsizing.PrintXmxXms

docker/heap-sizing/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<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>
+    <parent>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-starter-parent</artifactId>
+        <version>2.4.2</version>
+        <relativePath/> <!-- lookup parent from repository -->
+    </parent>
+    <groupId>com.baeldung.docker</groupId>
+    <artifactId>heap-sizing</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+    <name>heap-sizing</name>
+    <description>Demo project for Spring Boot</description>
+    <properties>
+        <java.version>11</java.version>
+    </properties>
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-webflux</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>io.projectreactor</groupId>
+            <artifactId>reactor-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-maven-plugin</artifactId>
+                <configuration>
+                    <image>
+                        <name>heapsizing-demo</name>
+                    </image>
+                </configuration>
+            </plugin>
+            <plugin>
+                <groupId>com.google.cloud.tools</groupId>
+                <artifactId>jib-maven-plugin</artifactId>
+                <version>2.7.1</version>
+
+                <configuration>
+                    <to>
+                        <image>heapsizing-demo-jib</image>
+                    </to>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>

docker/heap-sizing/src/main/java/com/baeldung/docker/heapsizing/HeapSizingApplication.java

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+package com.baeldung.docker.heapsizing;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+import java.util.logging.Logger;
+
+import static com.baeldung.docker.heapsizing.PrintXmxXms.logMemory;
+
+@SpringBootApplication
+public class HeapSizingApplication {
+    private static final Logger logger = Logger.getLogger(HeapSizingApplication.class.getName());
+
+    public static void main(String[] args) {
+        SpringApplication.run(HeapSizingApplication.class, args);
+        logMemory(logger);
+    }
+
+}

docker/heap-sizing/src/main/java/com/baeldung/docker/heapsizing/PrintXmxXms.java

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+package com.baeldung.docker.heapsizing;
+
+import java.lang.management.ManagementFactory;
+import java.lang.management.MemoryMXBean;
+import java.lang.management.MemoryPoolMXBean;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+public class PrintXmxXms {
+
+    private static final Logger logger = Logger.getLogger(PrintXmxXms.class.getName());
+
+    public static void main(String[] args) {
+        logMemory(logger);
+    }
+
+    /**
+     * We're reusing this method in HeapSizingApplication, therefore this method was extracted
+     * to avoid repetition.
+     */
+    static void logMemory(Logger logger) {
+        float mb = 1024f * 1024f;
+        MemoryMXBean memoryBean = ManagementFactory.getMemoryMXBean();
+
+        // xmx controls the maximum size of the memory allocation pool,
+        // which includes the heap, the garbage collector's survivor space, and other pools.
+        float xmx = memoryBean.getHeapMemoryUsage().getMax() / mb;
+        float xms = memoryBean.getHeapMemoryUsage().getInit() / mb;
+        logger.log(Level.INFO, "Initial Memory (xms) : {0}mb", xms);
+        logger.log(Level.INFO, "Max Memory (xmx) : {0}mb", xmx);
+
+        for (MemoryPoolMXBean mp : ManagementFactory.getMemoryPoolMXBeans()) {
+            logger.log(Level.INFO, "Pool: {0} (type {1}) = {2}", new Object[]{ mp.getName(), mp.getType(), mp.getUsage().getMax() / mb });
+        }
+    }
+}