Knowledge Base

Articles tagged as memory

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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Control number of file handles created per Lucene Index

In the more recent Neo4j versions (3.4 onwards), the number of file handles opened by Neo4j may seem to increase compared with that in older versions. Native indexes require a…

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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 to configure off-heap transaction state

Commencing with Neo4j 3.5, it is possible to store some of transactions' data in off-heap memory. This can help to reduce GC pressure and/or prevent OOM crashes in a limited…

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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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Large Delete Transaction Best Practices in Neo4j

In order to achieve the best performance, and avoid negative effects on the rest of the system, consider these best practices when processing large deletes. Start by identifying which situation…

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Linux Out of Memory killer

The Out Of Memory Killer or OOM Killer is a process that the linux kernel employs when the system is critically low on memory. This situation occurs because the linux…

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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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Understanding memory consumption

So you have configured Neo4j to use 4GB of heap and 6GB of page cache and sat back relaxed, thinking the Java process would not go above 10GB in your…

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