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WTF Connection pools

java-interview-questions-answers

Let’s talk about connection pools. I claim that: Default settings of most popular connection pools are poor! For you, it means: Go review your connection pool settings. You might have a problem if you rely on default settings. You may have memory leaks and unresponsive application (even if load is not high at all). Below I will show some of ...

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Using Java Flight Recorder with OpenJDK 11

Java Flight Recorder (JFR) used to be a commercial add-on of the Oracle JDK. As it’s been open sourced recently along with Java Mission Control, everyone using OpenJDK 11 can now troubleshoot their Java apps with this excellent tool for free of charge. JFR, being a proprietary solution formerly, might be lesser known for those relying on previous versions of ...

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Exploring the Spline Data Tracker and Visualization tool for Apache Spark (Part 2)

In part 1 we have learned how to test data lineage info collection with Spline from a Spark shell. The same can be done in any Scala or Java Spark application. The same dependencies for the Spark shell need to be registered in your build tool of choice (Maven, Gradle or sbt): groupId: za.co.absa.spline artifactId: spline-core version: 0.3.5 groupId: za.co.absa.spline artifactId: spline-persistence-mongo ...

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Dropping Raw String Literals from JDK 12

It has been proposed that raw string literals (preview) be dropped from JDK 12 (which enters Rampdown Phase One on December 13). Brian Goetz has written a detailed description of the motivations for dropping this preview feature (JEP 326). There is also discussion on this on the Java subreddit. In the post “JSR 386 (Java SE 12) JEP Propose to ...

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What’s the case for your API?

java-interview-questions-answers

Disclaimer: In pure REST, API’s are opaque and the URL should be whatever what was sent as a link in the response to a previous request. But, I’m not talking pure REST, I’m talking more pragmatic APIs which involve some concepts from REST and as well as general API best practices. When writing an API, it starts simple. You identify the ...

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Build a Basic App with Spring Boot and JPA using PostgreSQL

spring-interview-questions-answers

“I love writing authentication and authorization code.” ~ No Java Developer Ever. Tired of building the same login screens over and over? Try the Okta API for hosted authentication, authorization, and multi-factor auth. Every non-trivial application needs a way to save and update data: a resource server that is accessible via HTTP. Generally, this data must be secured. Java is ...

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Java Security Animated

Overview Java security has been inherently a complex topic ever since the introduction of the security sandbox model in JDK 1.2 and the evolution of security APIs provided by the JDK. A similar issue is observed with the concurrency utilities and a tool called Java Concurrent Animated has been developed in order to lower the entry barrier towards these utilities ...

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Reactive Spring Webflux with AWS DynamoDB

spring-interview-questions-answers

AWS has released AWS SDK for Java version 2, the SDK now supports non-blocking IO for the API calls of different AWS services. In this post I will be exploring using the DynamoDB API’s of the AWS SDK 2.x and using Spring Webflux stack to expose a reactive endpoint – this way the application is reactive end to end and presumably ...

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