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Its amazing how after working so many years on Javascript, I still get some of the basic concepts wrong. The concept in question is Event loop and Call Stack. To get it refreshed, here is the teaser. What is the output of the below snippet. function printHello() { console.log("Hello"); } function blockFor1Sec() { let arr = []; for (let i = 0; i < 100000; ++i) { arr.push(i); } } setTimeout(printHello, 0); blockFor1Sec(); console.log("Me first!");...

In a complex multi data center Kafka deployments, it is also important to estimate no. of partition each thread will be handling per compute. It is very important parameter to tune. For example, if you are seeing high lag and less CPU usage, it could be because a single thread is handling too much partitions and it might be advisable to increase the no. of threads per compute. Let me take a hypothetical example of...

Multithreading / Concurrency have always been the favorite topic of mine. It gives me a pure joy to extract most out of a machine by loading the CPU with work just like a master exploiting its slaves :) Unfortunately, these days due to distributed nature of computing, most of the time in a machine is spent waiting on I/O (either from database, API’s etc.) and our CPU just sits idle most of the time. Kafka...

I wrote this article Debugging SSL Issues in Java almost 4 years ago. I am writing again a new post on the same topic because I faced the same issue and that article didn’t help me. So I’ll list my new learnings in this post and it will be to the point. Use -Djavax.net.debug=all to command line When using Java program, you can add -Djavax.net.debug=all to the command line to produce debug output of the...

Recently, It got me thinking why do lambda functions require final variables after all. This is not a requirement in Kotlin. For example, this code runs fine in kotlin fun main(args: Array<String>) { var index = 5 val list = mutableListOf<Int>() list.add(5) list.forEach(Consumer { o: Int -> index = 10 println(o * index) }) } Whereas a similar function in Java will give error public static void main(String[] args) { Integer index = 5; List<Integer>...

Recently, there has been a new trend of smaller keyboards because they consume lesser real estate. These come in various form factors such as Tenkeyless (TKL), 60%, 65%, 80%, 96% keyboards. 100% - These are our regular full size keyboards. This one is my older and the best in this category Das Keyboard Professional 65% - These do not have function keys and neither the numpad. This one is Ducky one 2 SF TKL or...

In order to make our application, highly available and fault tolerant, I have been researching a lot on best disaster recovery strategy for Kafka. In earlier relational systems, such as MySQL or Oracle, it was standard to have an active-passive cluster where in the application does reads and writes to a primary cluster. This primary cluster is asynchronously replicated to a secondary cluster. The application falls back to the secondary cluster incase the primary cluster...

Continuing article on Kotlin for Java Developers, Let’s continue the differences: Inheritance Singletons when instead of switch Mutable variables inside lambda With keyword Inheritance Classes are final by default. We have to use open keyword to tell compiler to indicate that class is extensible Singletons In Kotlin, singletons can be simply defined using object keyword object CompanyCommunications { val currentYear = Year.now().value fun getTagLine() = "Our company rocks" fun getCopyrihtLine() = "Copyright"; } Static keyword...

Continuing article on Kotlin for Java Developers, Let’s continue the differences: Access Modifiers Defining Classes and Constructors Multiple constructors Generate Getters and Setters Data classes Extension Functions Access Modifiers Default top level visibility is public whereas its package private in java There is no restriction to have class names and filenames so its possible to declare multiple public classes in single Kotlin file There is something called private class in Kotlin which means only classes...

I have been learning Kotlin in my free time and I must say I have been glued to it since then due to its conciseness and addressing some of the issues which are there in Java. Hence, In this part I post, we will look at differences between Kotlin and Java from the programmer’s perspective. We will cover the runtime aspects and interoperability in the later posts. Equality differences No checked exceptions Wrapper classes Traditional...