spark

Mod

by Iucko

spark is a performance profiler for Minecraft clients, servers and proxies.

Type

Mod

CurseForge Downloads

209,740,934

CurseForge ID

361579

Modrinth Downloads

21,804,888

Modrinth ID

l6YH9Als

Last Updated

Sep 12, 2026

Description

spark is a performance profiler for Minecraft clients, servers and proxies.

(The version here on CurseForge is for Fabric/Forge/NeoForge only!)

Useful Links

Website - browse the project homepage
Documentation - read documentation and usage guides
Downloads - latest plugin/mod downloads

BisectHosting

spark is proudly sponsored by BisectHosting.

BisectHosting are Minecraft server hosting experts, ready to help you create and host your very own server! They are a trusted and well-established hosting provider in the community, and provide an outstanding level of service that we are happy to recommend. There is a special 25% off discount available for spark users - click the link above to create your server today.

What does it do?

spark is made up of a number of components, each detailed separately below.

⚡ CPU Profiler

spark's profiler can be used to diagnose performance issues: "lag", low tick rate, high CPU usage, etc.

It is:

Lightweight - can be ran in production with minimal impact.
Easy to use - no configuration or setup necessary, just install the plugin/mod.
Quick to produce results - running for just ~30 seconds is enough to produce useful insights into problematic areas for performance.
Customisable - can be tuned to target specific threads, sample at a specific interval, record only "laggy" periods, etc
Highly readable - simple tree structure lends itself to easy analysis and interpretation. The viewer can also apply deobfuscation mappings.

It works by sampling statistical data about the servers activity, and constructing a call graph based on this data. The call graph is then displayed in an online viewer for further analysis by the user.

⚡ Memory Inspection

spark includes a number of tools which are useful for diagnosing memory issues with a server.

Heap Summary - take & analyse a basic snapshot of the servers memory

A simple view of the JVM's heap, see memory usage and instance counts for each class
Not intended to be a full replacement of proper memory analysis tools. (see below)

Heap Dump - take a full (HPROF) snapshot of the servers memory

Dumps (& optionally compresses) a full snapshot of JVM's heap.
This snapshot can then be inspected using conventional analysis tools.

GC Monitoring - monitor garbage collection activity on the server

Allows the user to relate GC activity to game server hangs, and easily see how long they are taking & how much memory is being free'd.
Observe frequency/duration of young/old generation garbage collections to inform which GC tuning flags to use

⚡ Server Health Reporting

spark can report a number of metrics summarising the servers overall health.

These metrics include:

TPS - ticks per second, to a more accurate degree indicated by the /tps command
Tick Durations - how long each tick is taking (min, max and average)
CPU Usage - how much of the CPU is being used by the server process, and by the overall system
Memory Usage - how much memory is being used by the process
Disk Usage - how much disk space is free/being used by the system

As well as providing tick rate averages, spark can also monitor individual ticks - sending a report whenever a single tick's duration exceeds a certain threshold. This can be used to identify trends and the nature of performance issues, relative to other system or game events.