Merge pull request #2184 from pareenaverma/content_review

First tech review of java flamegraph LP, wrk2 architecture issue with…

Author: pareenaverma

content/learning-paths/servers-and-cloud-computing/java-perf-flamegraph/1_setup.md

@@ -9,67 +9,85 @@ layout: learningpathall
 
 ## Before You Begin 
 - There are numerous performance analysis methods and tools for Java applications, among which the call stack flame graph method is regarded as a conventional entry-level approach. Therefore, generating flame graphs is considered a basic operation.
-- Various methods and tools are available for generating Java flame graphs, including async-profiler, Java Agent, jstack, JFR (Java Flight Recorder), etc.
-- This LP (Learning Path) focuses on introducing two simple and easy-to-use methods: async-profiler and Java Agent.
+- Various methods and tools are available for generating Java flame graphs, including `async-profiler`, `Java Agent`, `jstack`, `JFR` (Java Flight Recorder), etc.
+- This Learning Path focuses on introducing two simple and easy-to-use methods: `async-profiler` and `Java Agent`.
 
 
 ## Setup Benchmark Server - Tomcat
 - [Apache Tomcat](https://tomcat.apache.org/) is an open-source Java Servlet container that enables running Java web applications, handling HTTP requests and serving dynamic content.
 - As a core component in Java web development, Apache Tomcat supports Servlet, JSP, and WebSocket technologies, providing a lightweight runtime environment for web apps.
 
-1. So you should install Java Development Kit (JDK) first.
+1. Start by installing Java Development Kit (JDK) on your Arm-based server:
 ```bash
 sudo apt update
 sudo apt install -y openjdk-21-jdk
 ```
 
-2. Second, you can install Tomcat by either [building it from source](https://github.com/apache/tomcat) or downloading the pre-built package simply from [the official website](https://tomcat.apache.org/whichversion.html)
+2. Next, you can install Tomcat by either [building it from source](https://github.com/apache/tomcat) or downloading the pre-built package simply from [the official website](https://tomcat.apache.org/whichversion.html)
 ```bash
 wget -c https://dlcdn.apache.org/tomcat/tomcat-11/v11.0.9/bin/apache-tomcat-11.0.9.tar.gz
 tar xzf apache-tomcat-11.0.9.tar.gz
 ```
 
-3. If you intend to access the built-in Examples of Tomcat via an intranet IP or even an external IP, you need to modify a configuration file.
+3. If you intend to access the built-in examples of Tomcat via an intranet IP or even an external IP, you need to modify a configuration file as shown:
 ```bash
 vim apache-tomcat-11.0.9/webapps/examples/META-INF/context.xml
+```
+Then change the values:
+```console
 # change <Valve className="org.apache.catalina.valves.RemoteAddrValve" allow="127\.\d+\.\d+\.\d+|::1|0:0:0:0:0:0:0:1" />
 # to
 # <Valve className="org.apache.catalina.valves.RemoteAddrValve" allow=".*" />
-
-# now you can start Tomcat Server
+```
+Now you can start Tomcat Server:
+```bash
 ./apache-tomcat-11.0.9/bin/startup.sh
 ```
 
-4. If you can access the page at "http://${tomcat_ip}:8080/examples" via a browser, congratulations-you can proceed to the next benchmarking step.
+The output from starting the server should look like:
+
+```output
+Using CATALINA_BASE:   /home/ubuntu/apache-tomcat-11.0.9
+Using CATALINA_HOME:   /home/ubuntu/apache-tomcat-11.0.9
+Using CATALINA_TMPDIR: /home/ubuntu/apache-tomcat-11.0.9/temp
+Using JRE_HOME:        /usr
+Using CLASSPATH:       /home/ubuntu/apache-tomcat-11.0.9/bin/bootstrap.jar:/home/ubuntu/apache-tomcat-11.0.9/bin/tomcat-juli.jar
+Using CATALINA_OPTS:
+Tomcat started.
+```
+
+4. If you can access the page at "http://${tomcat_ip}:8080/examples" via a browser, you can proceed to the next benchmarking step.
 
 ![example image alt-text#center](./_images/lp-tomcat-homepage.png "Tomcat-HomePage")
 
 ![example image alt-text#center](./_images/lp-tomcat-examples.png "Tomcat-Examples")
 
 ## Setup Benchmark Client - [wrk2](https://github.com/giltene/wrk2)
-- wrk2 is a high-performance HTTP benchmarking tool specialized in generating constant throughput loads and measuring latency percentiles for web services.
-- As an enhanced version of wrk, wrk2 provides accurate latency statistics under controlled request rates, ideal for performance testing of HTTP servers.
+`wrk2` is a high-performance HTTP benchmarking tool specialized in generating constant throughput loads and measuring latency percentiles for web services. `wrk2` is an enhanced version of `wrk` that provides accurate latency statistics under controlled request rates, ideal for performance testing of HTTP servers.
 
-1. If you intend to use wrk2, you should install some essential tools before build it.
+1. To use `wrk2`, you will need to install some essential tools before you can build it:
 ```bash
 sudo apt-get update
 sudo apt-get install -y build-essential libssl-dev git zlib1g-dev
 ```
 
-2. Now you can clone and build it from source.
+2. Now you can clone and build it from source:
 ```bash
 sudo git clone https://github.com/giltene/wrk2.git
 cd wrk2
 sudo make
-# move the executable to somewhere in your PATH
+```
+Move the executable to somewhere in your PATH:
+```bash
 sudo cp wrk /usr/local/bin
 ```
 
 3. Finally, you can run the benchamrk of Tomcat through wrk2.
 ```bash
 wrk -c32 -t16 -R50000 -d60 http://${tomcat_ip}:8080/examples/servlets/servlet/HelloWorldExample
 ```
-        Below is the output of wrk2
+Shown below is the output of wrk2:
+
 ```console
 Running 1m test @ http://172.26.203.139:8080/examples/servlets/servlet/HelloWorldExample
   16 threads and 32 connections

content/learning-paths/servers-and-cloud-computing/java-perf-flamegraph/_index.md

@@ -1,13 +1,13 @@
 ---
-title: Java Performance Analysis - FlameGraph
+title: Analyze Java Performance on Arm servers using FlameGraphs
 
 draft: true
 cascade:
     draft: true
 
 minutes_to_complete: 30
 
-who_is_this_for: This is an introductory guide for individuals aiming to perform performance analysis of Java applications on the ARM Neoverse platform using flame graphs. 
+who_is_this_for: This is an introductory topic for software developers looking to analyze the performance of their Java applications on the Arm Neoverse based servers using flame graphs. 
 
 learning_objectives: 
     - How to set up tomcat benchmark environment
@@ -17,13 +17,12 @@ learning_objectives:
 prerequisites:
     - Basic familiarity with Java applications
     - Basic familiarity with flame graphs
-    - Basic familiarity with Tomcat, wrk, etc
 
 author: Ying Yu, Martin Ma
 
 ### Tags
 skilllevels: Introductory
-subjects: Java Performance Analysis
+subjects: Performance and Architecture
 armips:
     - Neoverse
 
@@ -34,13 +33,13 @@ tools_software_languages:
     - FlameGraph
     - wrk2
 operatingsystems:
-    - Ubuntu 24
+    - Linux
 
 
 further_reading:
     - resource:
-        title: PLACEHOLDER MANUAL 
-        link: PLACEHOLDER MANUAL LINK
+        title: OpenJDK Wiki 
+        link: https://wiki.openjdk.org/
         type: documentation
     - resource:
         title: PLACEHOLDER BLOG