Knowledge Base

Articles tagged as jvm

Retired: Changing your Garbage Collection Method to G1

When to Use G1: By default, Neo4j versions 2.2 and earlier use Concurrent Mark and Sweep (CMS) for garbage collection. Customers with large heaps or who are seeing unacceptable garbage…

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Enabling GC Logging

What is Garbage collection and why enabling it? A garbage collection event is a complete pause of the java application (ie: neo4j-server). It can be identified in the debug.log as…

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Getting a JVM heap dump

This document provides the process of creating a heap-dump on a java machine to investigate potential memory leaks. Although a heap dump will be auto generated when OutOfMemoryError is thrown…

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How do I enable Java Flight Recorder and view the Results

Java Flight Recorder can be used to capture low level Java properties and run-time data about Java processes, for example Neo4j. Per https://docs.oracle.com/javase/8/docs/technotes/guides/troubleshoot/tooldescr002.html To enable the Java Flight Recorder the…

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How to estimate initial memory configuration

The initial and eventual memory configuration parameters can be a moving target, based on how your store changes in size and how your workload increases or changes over time. This…

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Long GC Pauses caused by application code calling System.gc()

When investigating the cause of long garbage collection cycles, it is often useful to enable GC logging. You can do so by following the product documentation. Once this is enabled,…

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Recommendations for recovery upon Out Of Memory error

It is possible to configure the JVM (Java Virtual Machine) such that upon encountering an OOM (Out-Of-Memory) error it will force an exception and crash or simply shut down the…

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