jvm Archives - Tutorial Guruji

Is there any performance downsides to using the `-XX:+PerfDisableSharedMem` JVM flag?

Java March 25, 2021

From what I’ve read online, it sounds like a lot of people recommend setting the -XX:+PerfDisableSharedMem JVM flag to fix high GC pause latencies due to IO blocking when the garbage collector tries …

A simple Java HTTP server fails with ApacheBench but works fine on a browser

Java January 22, 2021

As part of a concurrency blog series, I was building the simplest HTTP server in different languages (Java, Kotlin, Rust, Go, JS, TS) and everything works fine for everything except Java/Kotlin, aka …

Is JVM smart enough?

Java January 5, 2021

I know that JVM will be smarter as the time goes on (optimize code, etc …). But how smarter can it be? Let’s consider some real scenario, that I often see. public static String toJson(final Object …

Java memory settings in a docker container

Java December 2, 2020

I have a Java application, based on Java8 OpenJDK. It’s running in a docker container which has a limit of 20GB. The -Xms and -Xmx settings of tomcat is set as follows: -Xms = 60% of the container …

SonarQube: Error: Could not create the Java Virtual Machine

Java November 16, 2020

I’m new to SonarQube, When i run “C:sonarqube-8.5.1.38104binwindows-x86-64StartSonar.bat”, i receives below error, –> Wrapper Started as Console Launching a JVM… Picked up …

How to preload used class when JVM starts?

Java October 26, 2020

I am developing a messaging system with Java that requires low latency processing (under 1 second). However, JVM takes warm-up time to process the first input data that causes latency increase (about …

JVM recursive class initialization implementation

Java October 21, 2020

Am studying JVM spec/internals, and would like to understand how circularly-referenced recursive class initialization is supposed to happen correctly. Looking at this example: class CA extends Object …

Where does the HotSpot JVM store interpreted bytecode?

Java July 7, 2020

I’ve been wondering where interpreted byte-code of methods are stored internally in the JVM (specifically HotSpot x64). I know that methods that are JIT-ed are stored and can be accessed in the Method …

Why does the JVM consider superinterfaces when resolving non-interface methods? (JVM 5.4.3.3)

Java April 23, 2020

The JVM spec (5.4.3.3) describes how method resolution is done for method refs. If it cannot find a method in a class or its superclasses, it tries to find the method in the superinterfaces. What is …

Is young generation still gets speed advantage if finalize() is guaranteed to be called when collecting?

Java November 7, 2019

Why garbage collection in young generation is fast depends on a fact: most objects in young generation die soon. So when a young generation collection happens, few objects which are still alive are …