Recent On WhiteBoard Talks

• Security List and Route Table in OCI
  Security Lists and Route Tables are both essential components of Oracle Cloud Infrastructure (OCI) networking, but they serve different purposes: Lets consider we have a Virtual Cloud Network (VCN) in Oracle Cloud Infrastructure (OCI) with two subnets: Subnet Direction Protocol Port(s) Source Destination Description Subnet A Ingress TCP 80, 443… Read More »Security List and Route Table in OCI
• How to Increase Replication Factor for a Kafka topic
  Have you noticed that some topics in your Kafka cluster have a suboptimal replication factor? This could be due to initial setup, low traffic, or the product being in its early stages. As your data grows, it’s important to ensure durability and scalability of your Kafka cluster. Our aim is… Read More »How to Increase Replication Factor for a Kafka topic
• How to reload .bash_profile from the command line
  Just sharing few commands to load a .bash_profile without exiting from terminal or command line
• Inheritance hierarchies in Jackson
  We will look at how class hierarchies in Jackson works.  We will take an example of building a Notification Service Pojo to demonstrate this. Below is the package/class diagram for this.
• Kafka Interview Questions
  Here is a list of top Kafka interview question based on my exposure to Apache Kafka Kafka Basics What is Apache Kafka What are topics and partitions  What are various components of Kafka What is a consumer group What is an offset What are the different ways to commit an… Read More »Kafka Interview Questions
• Gradle download sources and javadoc in eclipse or Intellij or Idea
  For different workspace sources and javadoc from maven repo can be download as follows: Eclipse For IntelliJ & Android Studio To apply and run plugins: References
• Finding Ulimit of Process and a User
  ulimit is a shell command to control the resources available to a bash shell and all the programs that are started from this shell. We can get and set  the ulimit of a process or a user  Ulimit of a process  Ulimit of a process can be found by doing cat… Read More »Finding Ulimit of Process and a User
• Import SSL Certificates in trust store
  First download certificate in java file Import it using keytool command Java Trust store location : <JRE_HOME>/lib/security/cacerts
• Java SSL PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
  Sometime back I got below error while connecting to SSL secured site in java. I was using java 8 update 60. Why this error comes and how to resolve it. We will see that. PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target Before getting… Read More »Java SSL PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
• Graceful shutdown of java process inside docker container
  Recently faced an issue where the docker stop was not calling a shutdown hook was not working correctly. The same application when run as a spring boot applicaiton or jar without docker invokes the shutdownhook.   During debugging found that the boot app inside the container is not geting SIGTERM when docker stop command… Read More »Graceful shutdown of java process inside docker container
• How to push as different user in github
  Remove all existing keys Generate ssh key for the current user which wants to commit to github add the ssh key for new user Initialise the new Repository  Add the remote url ( here note that we are not using https url) Add user name and email to git config… Read More »How to push as different user in github
• Hands on with ansible: Elastic Search
  Requirement: Update log4j2.properties on all elastic search servers, restart them and check if logs are being rolled and purged over or not. Use Case 1: Take backup of existing log4j2.properties if exists Update log4j2.properties of all the elastic search data and master nodes Restart elastic search server playbook : log4j-update.yml Use… Read More »Hands on with ansible: Elastic Search
• Exception stack trace suppressed after same exception many times + Java
  Sometimes, we have seen in logs same exception occurs continuously and you get full stacktrace of that exception. But after some time, you just get only exception message not full stack trace. The reason for this is below from java doc.   The compiler in the server VM now provides… Read More »Exception stack trace suppressed after same exception many times + Java
• Sort process by their memory usage (LINUX)
• Maximum Number Of Threads (Linux/MacOS) + OutOfMemory unable to create new native thread
  We create threads in application to improve performance. So, how many maximum threads can we create?? You might wondering we can create threads as much as memory is available in system. So If you try running below program, what is the output you are going to get?? So, only 2029… Read More »Maximum Number Of Threads (Linux/MacOS) + OutOfMemory unable to create new native thread