Software Engineering Tech Tips

About virtual thread in java

2024-02-06T01:34:00.000-08:00

In this blog post, I will introduce you to the concept of virtual threads in Java and how they can improve the performance and scalability of your applications that rely on networking I/O.

Virtual threads are lightweight threads that reduce the effort of writing, maintaining, and debugging high-throughput concurrent applications. They are instances of java.lang.Thread that are not tied to a specific operating system (OS) thread, but rather run on a small number of OS threads managed by the Java runtime. This allows the Java runtime to suspend and resume virtual threads when they perform blocking I/O operations, freeing up the OS threads for other tasks. Virtual threads typically have a shallow call stack and perform as few as a single HTTP client call or a single JDBC query. They are suitable for tasks that spend most of their time waiting for I/O, but not for long-running CPU-intensive tasks.

Virtual threads are supported by the Java Platform since Java SE 21. They are part of Project Loom, which aims to simplify concurrent programming in Java by providing new APIs and features for concurrency and parallelism. You can read more about the background and motivation of Project Loom in JEP 444.

To create a virtual thread, you can use the Thread.ofVirtual() method, which returns an instance of Thread.Builder that can be used to configure and start the virtual thread. For example:

Alternatively, you can use the Executors.newVirtualThreadExecutor() method, which returns an ExecutorService that creates a new virtual thread for each submitted task. For example:

java

Thread virtualThread = Thread.ofVirtual().start(() -> {

// Code to be executed by the virtual thread

});

AWS amplify hugo App build specification amplify.yml

2022-05-03T07:49:00.000-07:00

I needed a content-oriented site with solely static content for a little project I'm working on, so Hugo was an obvious choice. I looked into using AWS Amplify to host it, But the default amplify.yml not working for me and can't find the correct build file, I have modified the amplify.yml to build the Hugo cms.

Hope this is helpful, Please comment.

version: 1
frontend:
  phases:
    build:
      commands:
        - npm install
        - npm run build:webpack && npm run build:hugo
  artifacts:
    baseDirectory: dist
    files:
      - '**/*'
  cache:
    paths: []

Easy site migration with hugo cms and netlify

2022-04-24T07:07:00.001-07:00

Old slow non-secure drupal base Sri Lanka hotel booking website migrated to netlify platform. Using Hugo cms these contents easily be migrated to a static website.

The old backup data source can easily load to Hugo cms using gomplate tool.

Gomplate : A flexible commandline tool for template rendering. Supports lots of local and remote datasources.

Reference :

https://srilanka.lowcosthotelbooking.com/

https://lowcosthotelbooking.com/

https://gohugo.io/

https://www.netlify.com/

https://gomplate.ca/

ERROR running force:org:create: You do not have access to the [ScratchOrgInfo] object

2021-08-14T23:20:00.002-07:00

Error : -

ERROR running force:org:create: You do not have access to the [ScratchOrgInfo] object

Solution :-

To enable Dev Hub in an org:

Log in as System Administrator to your Developer Edition, trial, or production org (for customers), or your business org (for ISVs).
From Setup, enter Dev Hub in the Quick Find box and select Dev Hub.
If you don't see Dev Hub in the Setup menu, make sure that your org is one of the supported editions.
To enable Dev Hub, click Enable.
After you enable Dev Hub, you can’t disable it.

git Update failed

2021-01-18T21:47:00.000-08:00

Issue - when you work with a large team, the git repository may have many branch creation and deletion operations, sometimes we may getting git update failed, when we try to update the whole repository.

Solution - Tyr > git fetch -p

-p, --prune

After fetching, remove any remote-tracking references that no longer exist on the remote. Tags are not subject to pruning if they are fetched only because of the default tag auto-following or due to a --tags option. However, if tags are fetched due to an explicit refspec (either on the command line or in the remote configuration, for example if the remote was cloned with the --mirror option), then they are also subject to pruning.

How to find best java libraries for your need ?

2020-07-29T00:25:00.003-07:00

Java is most mature language and have lot of java libraries build over the years. Maven repository is the best place to search java utility.

I have created jar search engine based on Maven repository index, you can search java libraries by any keywords.

Java library search - http://gcloganalyzer.com/jar-search

Json viewer and Editor - http://gcloganalyzer.com/json-viewer/index.html

kubernetes Tips for Java Developer

2020-07-23T03:04:00.000-07:00

kubernetes Tips for Java Developer

Get Pod list

kubectl get pods

Tail kubernetes logs in pod

kubectl logs -f pod-id --since=10m

How to select GC for java application

2020-05-15T11:54:00.002-07:00

Which garbage collection(GC) algorithm suite for the application

If you don't have any strict pause-time requirements, first run your application and allow the VM to select a collector.

If necessary, adjust the heap size to improve performance. If the performance still doesn't meet
your performance, then use the specific collector and try.

Performance is dependent on the size of the heap, the amount of live data maintained by the
application, and the number and speed of available processors.

If the recommended collector doesn't achieve the desired performance, then first attempt to
adjust the heap and generation sizes to meet the desired goals. If performance is still
inadequate, then try a different collector: Use the concurrent collector to reduce pause-time,
and use the parallel collector to increase overall throughput on multiprocessor hardware.

Available Collector in Oracle JDK

-XX:+UseSerialGC

-XX:+UseParallelGC

-XX:+UseG1GC

-XX:+UseConcMarkSweepGC

-XX:UseZGC

How to enable GC logs

Turning on GC Logging in Java 7 / 8

java -XX:+PrintGCDetails -XX:+PrintGCDateStamps - Xloggc: <file-path>

Turning on GC Logging in Java 9 and Up

**java –Xlog:gc*:file=<file-path>:filecount=10,filesize=10M**

Dynamically Turning on GC Logging in Java 9 and Up

jcmd <pid> VM.log what=gc output=<file-path>

How to analyze GC logs

[0.010s][info][gc] Using G1

[0.028s][info][gc] Periodic GC disabled

[0.584s][info][gc] GC(0) Pause Young (Normal) (G1 Evacuation Pause) 23M->4M(130M) 3.386ms

[0.885s][info][gc] GC(1) Pause Young (Normal) (GCLocker Initiated GC) 38M->6M(130M) 3.475ms

[1.782s][info][gc] GC(2) Pause Young (Concurrent Start) (Metadata GC Threshold) 77M->8M(130M) 3.816ms

[1.782s][info][gc] GC(3) Concurrent Cycle

[1.789s][info][gc] GC(3) Pause Remark 9M->9M(40M) 2.746ms

[1.791s][info][gc] GC(3) Pause Cleanup 9M->9M(40M) 0.043ms

[1.792s][info][gc] GC(3) Concurrent Cycle 9.942ms

[2.141s][info][gc] GC(4) Pause Young (Normal) (G1 Evacuation Pause) 27M->10M(40M) 5.106ms

[2.404s][info][gc] GC(5) Pause Young (Normal) (G1 Evacuation Pause) 29M->11M(40M) 2.537ms

[2.628s][info][gc] GC(6) Pause Young (Normal) (G1 Evacuation Pause) 29M->12M(40M) 3.846ms

This is an example of a CG log file , reading and analyzing this text file is a tedious task. There are some tools available for log analysis.

GC Log Analyzer - http://www.gcloganalyzer.com

CGEasy - https://gceasy.io

GCViewer - https://github.com/chewiebug/GCViewer

hamcrest and junit java.lang.NoSuchFieldError: NONE

2018-11-01T03:11:00.000-07:00

Issue - When you using hemcrest with JUnit5 you may get java.lang.NoSuchFieldError: NONE error.

Solution - Add junit-vintage-engine to classpath

<dependency>
<groupId>org.junit.vintage</groupId>
<artifactId>junit-vintage-engine</artifactId>
<version>5.3.1</version>
<scope>test</scope>
</dependency>

Full Exception -

java.lang.NoSuchFieldError: NONE

at org.hamcrest.DiagnosingMatcher.matches(DiagnosingMatcher.java:12)
at org.hamcrest.beans.SamePropertyValuesAs.hasMatchingValues(SamePropertyValuesAs.java:63)
at org.hamcrest.beans.SamePropertyValuesAs.matchesSafely(SamePropertyValuesAs.java:31)
at org.hamcrest.TypeSafeDiagnosingMatcher.matches(TypeSafeDiagnosingMatcher.java:55)
at org.hamcrest.MatcherAssert.assertThat(MatcherAssert.java:12)
at org.hamcrest.MatcherAssert.assertThat(MatcherAssert.java:8)
at com.codegen.ShopTest.testExternalizable(ShopTest.java:77)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:515)
at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:115)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$6(TestMethodTestDescriptor.java:171)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:72)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:167)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:114)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:59)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:105)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:72)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:95)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:71)
at java.util.ArrayList.forEach(ArrayList.java:1249)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:110)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:72)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:95)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:71)
at java.util.ArrayList.forEach(ArrayList.java:1249)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:110)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:72)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:95)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:71)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:32)
at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:51)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:220)
at org.junit.platform.launcher.core.DefaultLauncher.lambda$execute$6(DefaultLauncher.java:188)
at org.junit.platform.launcher.core.DefaultLauncher.withInterceptedStreams(DefaultLauncher.java:202)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:181)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:128)
at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:74)
at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)

Hope this will save your time.

How to track java Exceptions in Tomcat Log

2017-09-26T08:23:00.000-07:00

We have monitoring large java application logs (Ex - Hotel Directory ) , there are many logs entry in our log file and can not figure out Java Exceptions by looking at catalina.out log file.

Using with tail and grep command in Linux, we can track Java Exception, This is very helpful to us Track exception in testing and production environment.

In Tomcat
tail -f catalina.out | grep -P "(WARN|ERROR|^\tat |Exception|^Caused by: |\t... \d+ more)"

In Any Java Application Logfile
tail -f logfile | grep -P "(WARN|ERROR|^\tat |Exception|^Caused by: |\t... \d+ more)"

InteljIDEA find and replace with advance regular expression

2016-06-29T10:00:00.000-07:00

Day to day text editing task going to easy with regular expression. InteljIDAE provide rich editing experience with power of regex.

Example -

What I have to do - Create POST request like line number 1, using list of text.

Solution - Check screenshot bellow.

What is the software license simply says ?

2016-05-30T11:27:00.000-07:00

GNU General Public License - you can copy, distribute, and modify it as long as you track changes in source files and keep it under GNU GPL. You can even distribute it commercially, but you must disclose the source code or obtain a commercial license.
MIT License (Expat) - Commercial friendly
Apache License 2.0 (Apache-2.0) - Commercial friendly, You can use it as long as you keep the Apache license included and display it in your program's copyright notice.
GNU General Public License v3 (GPL-3) -todo
GNU General Public License v2.0 (GPL-2.0) -todo
GNU Lesser General Public License v2.1 (LGPL-2.1) -todo
BSD 2-Clause License (FreeBSD/Simplified) -todo
BSD 3-Clause License (Revised) -todo
Mozilla Public License 2.0 (MPL-2.0) -todo
Do What The F*ck You Want To Public License v2 (WTFPL-2.0) -Commercial friendly
Eclipse Public License 1.0 (EPL-1.0) - todo
Common Development and Distribution License (CDDL-1.0) -todo
Boost Software License 1.0 (BSL-1.0) -todo
Mozilla Public License 1.1 (MPL-1.1) -todo
Common Public License 1.0 (CPL-1.0) - You can use it in commercial applications.
OpenSSL License (OpenSSL) -todo

Angular 2 Typescript without node or npm

2016-05-28T21:50:00.001-07:00

To getting start with angular2 app, we need to setup some bunch of tool and boilerplate codes. Fortunately there are many easy getting-start projects available for angular2. Those are angular-cli , angual2-seed etc. Anyway we need to rely on node and npm, that would need for real angular2 projects.

But sometimes we need to test angular2 features and share demo codes with others. Installing large node modules and setting-up not worth for this kind of task.

However for small task you can use angular2 without npm.

have a look at github repository - https://github.com/ishara/angular2-without-npm

happy coding.

java typescript comparison

2016-05-28T01:09:00.001-07:00

I am working as java developer for many years with java swing and web service. However I don't like to write JavaScript as many java developer.

Currently we got chance to work with angular2 and Typescript. Now we can manage source easily with Typescript. It makes easier to write javascript code with Typescript.

Now I am trying to compare Typescript and Java.

Java hello world

public class HelloWorld {

    public static void main(String[] args) {
        System.out.println(" Hello Java Typescript comparison.");
    }
}

Typescript hello world
export class HelloWorld {

    public static main(args : string[]) {
        console.info(" Hello Java Typescript comparison.");
    }
}

HelloWorld.main(null);


Java class, constructor, method and static method
public class Student {
    private String name;
    private int age;

    public Student() {
    }
    public int getAge()
    {
        return age;
    }
    public static void staticMethod(int birthDay)
    {
        //implementation     
    }
}


Typescript class, constructor, method and static method
class Student {
    private name:string;
    private age:number;

    public constructor() {
        this.age = 0;
    }
    public getAge():number {
        return this.age;
    }
    public static staticMethod(birthDay:number) {
      //implementation 
    }
}


Java Types
public class TypesExample {
    private boolean isDone = true;
    private int intValue = 10;
    private float floatValue = 100;
    private long longValue = 1000;
    private String stringValue = "Java vs Typescripe";
    private int[] intArray ={1,2,3};
    private List<String> genericString;
    private BookingType bookingType = BookingType.FLIGHT;
    private Object anyType;

    enum BookingType{
        HOTEL,
        FLIGHT,
        CAR    }
}


Typescript Types
class TypesExample {
    private isDone : boolean = true;
    private intValue : number = 10;
    private floatValue : number = 100;
    private longValue : number = 1000;
    private stringValue : string = "Java vs Typescripe";
    private intArray : number[] = [1, 2, 3];
    private genericString : Arry<string>;
    private bookingType : TypesExample.BookingType = TypesExample.BookingType.FLIGHT;
    private anyType : any;
    constructor() {
    }
}

export namespace TypesExample {
    enum BookingType {
        HOTEL, FLIGHT, CAR    }
}

Angular2 bind data only if form is submitted

2016-05-27T12:28:00.000-07:00

How to bind data only if form is submitted in Angular2

This can be down with angular2 form handing with data-driven approach (User Angular FormBuilder).

Template File

<form [ngFormModel]='myForm' (ngSubmit)="onSubmit()">
  <input type="text" [ngFormControl]="myForm.controls['userName']" />
  <button type="submit">Submit</button>
  <button>Cancel</button>
</form>
<br>userName : {{originalUserName}}

Angular Component Class

export class AppComponent {
  myForm:ControlGroup;
  originalUserName:string;

  constructor(private _formBuilder:FormBuilder) {
    this.originalUserName = 'abc';
    this.myForm = _formBuilder.group({
      userName: [this.originalUserName]
    });
  }

  onSubmit(form) {
    this.originalUserName = this.myForm.controls['userName'].value;
  }
}

GitHub Example Source

Angular 2 Training video and E book

2016-05-25T11:19:00.001-07:00

Angular 2 is a best framework for building single page web application. Its provide major common tools and features set to enterprises developer life easier.

I have found Angular 2 Training video and book, prepared by Rangle.io Team. worth to have a look and read.

Download Angular 2 Training Videos

Angular 2 Book

create new github repository with existing repository without fork

2016-04-21T11:18:00.000-07:00

Clone existing repo into new project folder (e.g., my-proj).

git clone  https://github.com/ishara/my-proj  my-proj
cd my-proj

Delete everything "git-like" by deleting the .git folder.

rm -rf .git

Create a new git repo

You can writing code now. If you'd rather preserve your work under source control, consider taking the following steps.

Initialize this project as a local git repo and make the first commit:

git init
git add .
git commit -m "Initial commit"

Create a remote repository for your project (https://github.com/new).

Get its address (e.g. https://github.com/<my-org>/my-proj.git) and push the local repo to the remote.

git remote add origin <repo-address>
git push -u origin master

Elasticsearch UnknownHostException and marvel.agent.exporter issue

2015-09-07T22:50:00.000-07:00

Solution :

/etc/hosts file
add record
127.0.0.1 el-search

Error Log :

[2015-09-07 14:37:41,372][ERROR][marvel.agent.exporter ] [Archangel] could not connect to any configured elasticsearch instances: [[0:0:0:0:0:0:0:0]:9200]

[2015-09-07 14:30:24,693][WARN ][common.network ] failed to resolve local host, fallback to loopback
java.net.UnknownHostException: el-search: el-search: unknown error
at java.net.InetAddress.getLocalHost(InetAddress.java:1505)
at org.elasticsearch.common.network.NetworkUtils.<clinit>(NetworkUtils.java:55)
at org.elasticsearch.http.netty.NettyHttpServerTransport.<init>(NettyHttpServerTransport.java:165)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:422)
at org.elasticsearch.common.inject.DefaultConstructionProxyFactory$1.newInstance(DefaultConstructionProxyFactory.java:54)
at org.elasticsearch.common.inject.ConstructorInjector.construct(ConstructorInjector.java:86)
at org.elasticsearch.common.inject.ConstructorBindingImpl$Factory.get(ConstructorBindingImpl.java:98)
at org.elasticsearch.common.inject.FactoryProxy.get(FactoryProxy.java:52)
at org.elasticsearch.common.inject.ProviderToInternalFactoryAdapter$1.call(ProviderToInternalFactoryAdapter.java:45)
at org.elasticsearch.common.inject.InjectorImpl.callInContext(InjectorImpl.java:837)
at org.elasticsearch.common.inject.ProviderToInternalFactoryAdapter.get(ProviderToInternalFactoryAdapter.java:42)
at org.elasticsearch.common.inject.Scopes$1$1.get(Scopes.java:57)
at org.elasticsearch.common.inject.InternalFactoryToProviderAdapter.get(InternalFactoryToProviderAdapter.java:45)
at org.elasticsearch.common.inject.InjectorBuilder$1.call(InjectorBuilder.java:200)
at org.elasticsearch.common.inject.InjectorBuilder$1.call(InjectorBuilder.java:193)
at org.elasticsearch.common.inject.InjectorImpl.callInContext(InjectorImpl.java:830)
at org.elasticsearch.common.inject.InjectorBuilder.loadEagerSingletons(InjectorBuilder.java:193)
at org.elasticsearch.common.inject.InjectorBuilder.injectDynamically(InjectorBuilder.java:175)
at org.elasticsearch.common.inject.InjectorBuilder.build(InjectorBuilder.java:110)
at org.elasticsearch.common.inject.Guice.createInjector(Guice.java:93)
at org.elasticsearch.common.inject.Guice.createInjector(Guice.java:70)
at org.elasticsearch.common.inject.ModulesBuilder.createInjector(ModulesBuilder.java:59)
at org.elasticsearch.node.internal.InternalNode.<init>(InternalNode.java:210)
at org.elasticsearch.node.NodeBuilder.build(NodeBuilder.java:159)
at org.elasticsearch.bootstrap.Bootstrap.setup(Bootstrap.java:77)
at org.elasticsearch.bootstrap.Bootstrap.main(Bootstrap.java:245)
at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:32)
Caused by: java.net.UnknownHostException: el-search: unknown error
at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method)
at java.net.InetAddress$2.lookupAllHostAddr(InetAddress.java:928)
at java.net.InetAddress.getAddressesFromNameService(InetAddress.java:1323)
at java.net.InetAddress.getLocalHost(InetAddress.java:1500)

service monitorix start error

2015-09-07T22:15:00.002-07:00

Error Log

Starting monitorix: Can't locate HTTP/Server/Simple/CGI.pm in @INC (@INC contains: /usr/bin/lib /usr/lib/monitorix /usr/local/lib64/perl5 /usr/local/share/perl5 /usr/lib64/perl5/vendor_perl /usr/share/perl5/vendor_perl /usr/lib64/perl5 /usr/share/perl5 .) at /usr/lib/monitorix/HTTPServer.pm line 27.
BEGIN failed--compilation aborted at /usr/lib/monitorix/HTTPServer.pm line 27.
Compilation failed in require at /usr/bin/monitorix line 30.
BEGIN failed--compilation aborted at /usr/bin/monitorix line 30.

Solution

cp -r /usr/lib/perl5/vendor_perl/5.12.3/HTTP /usr/lib/monitorix/

is not a JMX compliant Standard MBean

2015-06-03T05:16:00.002-07:00

I got the fallowing exception and issue solved.

If your are using MBean , MBean Interface and Implementation should be in same package, Otherwise use MXBean.

javax.management.NotCompliantMBeanException: MBean class comlanka.rest.controller.DataManagerController does not implement DynamicMBean, and neither follows the Standard MBean conventions (javax.management.NotCompliantMBeanException: Class comlanka.rest.controller.DataManagerController is not a JMX compliant Standard MBean) nor the MXBean conventions (javax.management.NotCompliantMBeanException: comlanka.rest.controller.DataManagerController: Class comlanka.rest.controller.DataManagerController is not a JMX compliant MXBean)
at com.sun.jmx.mbeanserver.Introspector.checkCompliance(Introspector.java:176)
at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerMBean(DefaultMBeanServerInterceptor.java:317)
at com.sun.jmx.mbeanserver.JmxMBeanServer.registerMBean(JmxMBeanServer.java:522)
at comlanka.rest.controller.DataManagerController.registerMBean(DataManagerController.java:88)
at comlanka.rest.controller.DataManagerController.<init>(DataManagerController.java:76)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:408)
at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:147)
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:122)
at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:270)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1133)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1036)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:505)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:302)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:229)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:298)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:762)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:757)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:480)
at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:663)
at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:629)
at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:677)
at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:548)
at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:489)
at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:136)
at javax.servlet.GenericServlet.init(GenericServlet.java:158)
at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1231)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1144)
at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1031)
at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4913)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5200)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:725)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:701)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:717)
at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:940)
at org.apache.catalina.startup.HostConfig$DeployWar.run(HostConfig.java:1738)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)

Reference - https://blogs.oracle.com/jmxetc/entry/javax_management_standardmbean_when_and

Magnolia 5 project setup issue - Could not find artifact org.vaadin.addon

2013-06-23T12:10:00.000-07:00

I have try to build magnolia 5 project with maven option (An archetype to create a Magnolia project (a parent pom and a webapp ). and this project can not build due to fallowing error.

[ERROR] Failed to execute goal on project magnolia-webapp: Could not resolve dependencies for project magnolia-webapp:war:1.0-SNAPSHOT: The following artifacts could not be resolved: org.vaadin.addon:easyuploads:jar:7.0.0, org.vaadin.addons:refresher:jar:1.2.1.7, org.vaadin.addons:cssinject:jar:2.0.3, org.vaadin.addons:icepush:jar:0.5.3, org.vaadin.addons:gwt-graphics:jar:1.0.0, org.vaadin.addons:ckeditor-wrapper-for-vaadin:jar:7.8.3: Could not find artifact org.vaadin.addon:easyuploads:jar:7.0.0 in magnolia.nexus.public (http://nexus.magnolia-cms.com/content/groups/public/) -> [Help 1]

Solution - add fallowing vaadin addons respository to project pom.xml

<repository>
   <id>vaadin-addons</id>
   <url>http://maven.vaadin.com/vaadin-addons</url>

</repository>

sqlplus run all scripts in directory

2012-05-09T03:37:00.001-07:00

Get list of sql script.
ls *.sql > allsql.txt
Append '@' to every line.
sed s/^/@/ allsql.txt > allsql.sql
Now you can run all script.
@allsql.sql

How to Create fresh Database with setup data

2012-05-08T10:42:00.000-07:00

In agile software development process Database schema is changed time to time. Most of the enterprise software applications have 'system defined data sets' (Configurations, constants etc ) in the Database.In case of a new release, new client, testing etc. we need an empty Database structure with system defined data sets . This can be achieved by cleaning data-set, but sometimes this can be time consuming and error prone.

An empty Database structure can be created by modern DBMS. Setup data can also be exported from Database tables. Large applications may have complex relationships with tables and data extraction may be painful.

I have used Jailer (Database Subsetting Tool) to extract system defined data sets.

Jailer is a Database Subsetting and Browsing Tool. Exports consistent, referentially intact row-sets from relational databases (JDBC). Removes data w/o violating integrity. Generates DbUnit datasets, hierarchically structured XML and topologically sorted SQL-DML

Amazingly tool that is immensely useful (after some time spent on getting to know it properly).

SVN get revision number list for date period

2012-05-04T02:20:00.001-07:00

I need to get SVN revision numbers for particular date range , following steps has been done.

svn log -r {2012-05-01}:{2012-05-03} URL >> svn_log_r_2012_05_01_2012_05_03.txt
You will get all revisions for specified date range.
sed -n '/r[0-9]/p' svn_log_r_2012_05_01_2012_05_03.txt > out1.txt
Remove unwanted lines.
sed 's/$[^|]*$.*/\1/' out1.txt > out2.txt
Extract ‘r123’ pattern column.
sed 's/r/ /' out2.txt > revision_no_list.txt
Remove 'r' from file.

Resources - http://sed.sourceforge.net

Find duplicate line from file

2012-05-04T00:12:00.001-07:00

Finding duplicated lines can be done easily using regular expressions, Nowadays many text editors support regx.
Regx - ^(.*)(\r?\n\1)+$

This is my favorite editor IDEA community edition .

Software Engineering Tech Tips

About virtual thread in java

AWS amplify hugo App build specification amplify.yml

Easy site migration with hugo cms and netlify

ERROR running force:org:create: You do not have access to the [ScratchOrgInfo] object

git Update failed

How to find best java libraries for your need ?

kubernetes Tips for Java Developer

How to select GC for java application

Which garbage collection(GC) algorithm suite for the application

Available Collector in Oracle JDK

-XX:+UseSerialGC -XX:+UseParallelGC -XX:+UseG1GC -XX:+UseConcMarkSweepGC -XX:UseZGC

How to enable GC logs

Turning on GC Logging in Java 7 / 8

java -XX:+PrintGCDetails -XX:+PrintGCDateStamps - Xloggc: <file-path>

Turning on GC Logging in Java 9 and Up

java –Xlog:gc*:file=<file-path>:filecount=10,filesize=10M

Dynamically Turning on GC Logging in Java 9 and Up

jcmd <pid> VM.log what=gc output=<file-path>

How to analyze GC logs

hamcrest and junit java.lang.NoSuchFieldError: NONE

How to track java Exceptions in Tomcat Log

InteljIDEA find and replace with advance regular expression

What is the software license simply says ?

Angular 2 Typescript without node or npm

java typescript comparison

Angular2 bind data only if form is submitted

How to bind data only if form is submitted in Angular2

Angular 2 Training video and E book

create new github repository with existing repository without fork

Create a new git repo

Elasticsearch UnknownHostException and marvel.agent.exporter issue

service monitorix start error

is not a JMX compliant Standard MBean

Magnolia 5 project setup issue - Could not find artifact org.vaadin.addon

sqlplus run all scripts in directory

How to Create fresh Database with setup data

SVN get revision number list for date period

Find duplicate line from file

-XX:+UseSerialGC

-XX:+UseParallelGC

-XX:+UseG1GC

-XX:+UseConcMarkSweepGC

-XX:UseZGC

**java –Xlog:gc*:file=<file-path>:filecount=10,filesize=10M**