spark in FTB StoneBlock 4

spark is a performance profiler for Minecraft clients, servers and proxies. If your world is lagging, this is the tool that helps you find out why. It doesn't add blocks, items or machines, so there's nothing to craft or build with it.^[1]

This pack (version 1.21.0) ships spark 1.10.124 as the NeoForge jar. It has been in the pack since 1.0.0 or earlier.^[2]

What it does

• CPU Profiler: diagnoses performance issues like lag, low tick rate and high CPU usage. It is lightweight, needs no setup, and running it for just about 30 seconds is enough to give useful results.^[1]
• Memory Inspection: tools for diagnosing memory issues, including a heap summary, a full heap dump and garbage collection monitoring.^[1]
• Server Health Reporting: tracks TPS, tick durations, CPU usage, memory usage and disk usage. It can also report whenever a single tick runs longer than a threshold you set.^[1]

Where the quest book mentions it

spark doesn't have a quest of its own. It shows up in the "Welcome!" chapter, the first of 22 chapters in the book. That chapter has 4 quests, and the one that mentions spark, a quest in "Welcome!", has no title and is the last of the four. It is a list of handy commands, and the spark entry is /spark tps, which checks the server's TPS so you can see whether your world is lagging.^[3]

spark is a performance profiler for Minecraft clients, servers and proxies. In this pack you use it through chat commands, and the pack's quest book points you to the first one right at the start.^[1][3]

The quest book covers it in the first chapter, "Welcome!", in the quest a quest in "Welcome!". That quest lists the handy chat commands, and one of them is a spark command.^[3]

Your first steps

1. Open chat and type /spark tps. It checks the server's TPS, so you can see whether your world is lagging.^[3]
2. If the TPS looks bad, run spark's profiler to find out why. Running it for about 30 seconds is enough to give useful insights into problem areas.^[1]
3. Look up spark's own documentation for the exact profiler commands and options. The pack's config file header points to it as well.^[1][4]

What the pack sets

The pack's spark config is backgroundProfiler, which is set to true. That is the only option the pack's config file sets besides its header text.^[4]

Same as in the All the Mods 10: To the Sky 2.0.4 guide

spark works differently from most mods you'll meet in a modpack. It's a performance profiler for Minecraft clients, servers and proxies, so this section covers how its diagnostic tools work, not machines, power or automation.^[1]

It's made up of three separate components: a CPU profiler, memory inspection tools and server health reporting. Install it by adding the jar to the mods directory.^[1]

CPU profiler

The profiler is for diagnosing performance problems such as lag, low tick rate and high CPU usage. It works by sampling statistical data about system activity and building a call graph from it. That graph is then shown in an online viewer, where you can analyse it as a simple tree structure. The viewer can also apply deobfuscation mappings.^[1]

The project page describes the profiler like this:^[1]

• Lightweight: it can be run in production with minimal impact.^[1]
• Easy to use: no configuration or setup is necessary, you just install it.^[1]
• Quick: running for about 30 seconds is enough to give useful insight into problem areas.^[1]
• Customisable: you can target specific threads, sample at a specific interval, or record only "laggy" periods.^[1]

Profiler engines

There are two profiler engines. The first uses native AsyncGetCallTrace and perf_events through async-profiler, and it's only available on Linux x86_64 systems. The second uses the built-in Java ThreadMXBean, an improved version of the WarmRoast profiler by sk89q.^[1]

Memory inspection

For memory problems, spark includes three tools:^[1]

• Heap Summary: a basic snapshot of the server's memory. It shows memory usage and instance counts for each class in the JVM's heap. It's not meant to replace proper memory analysis tools.^[1]
• Heap Dump: a full HPROF snapshot of the JVM's heap, optionally compressed. You can inspect it with conventional analysis tools.^[1]
• GC Monitoring: watches garbage collection activity so you can relate it to server hangs and see how long collections take and how much memory they free. You can also observe how often young and old generation collections happen and how long they last, which helps you pick GC tuning flags.^[1]

Server health reporting

spark can report metrics that summarise the overall health of the server:^[1]

• TPS: ticks per second, with the /tps command giving a more accurate figure.^[1]
• Tick durations: how long each tick takes (min, max and average).^[1]
• CPU usage: how much CPU the server process uses, and how much the overall system uses.^[1]
• Memory usage: how much memory the process is using.^[1]
• Disk usage: how much disk space is free or in use on the system.^[1]

Besides tick rate averages, spark can monitor individual ticks and send a report whenever a single tick's duration goes over a set threshold. That helps you spot trends and the nature of a performance problem relative to other system or game events.^[1]

spark doesn't have tiers or a progression ladder in this pack. You don't unlock it, upgrade it or gate it behind other machines. The pack's quest book only touches it through one command.^[3]

That command is in the very first chapter of the quest book, "Welcome!" (chapter 1 of 22). The untitled quest a quest in "Welcome!" there is a checkmark quest that lists useful commands: /home, /back, /spawn and /spark tps. So you meet spark on day one, right alongside the basic teleport commands.^[3]

I can't confirm anything beyond that command from the pack's quests, so there are no tiers or crafting steps to cover for spark.^[3]

Spark only shows up in one place in the pack's quest book: the opening "Welcome!" chapter, which is chapter 1 of 22 and has 4 quests. The other three quests in it cover creating and joining a team, reporting bugs, and an overview of the pack. None of them mention spark.^[3]

The commands quest

The quest that mentions spark is a quest in "Welcome!", which the book gives no title of its own. It is the last of the four quests in the chapter. Its only task is a checkmark, so there is nothing to craft or hand in.^[3]

The quest text is a short list of useful commands. The spark one is /spark tps, which checks the server's TPS. The quest says it is useful for seeing whether your world is lagging.^[3]

The same quest also lists /home, /back and /spawn. It notes that the lobby is very important in this pack.^[3]

The Mekanism chapter, which sits in the "Forgotten Technology" group, has no spark content. This is the only quest involving the mod.^[5]

Same as in the All the Mods - Gravitas 4.0 guide

spark is a performance profiler, and this pack ships it with almost nothing configured. The whole config file has just one real setting, so there isn't much to tweak.^[1][6]

Background profiler

The one option that matters is backgroundProfiler. This pack sets it to true.^[6]

spark's profiler is described as lightweight enough to run in production with minimal impact, so leaving it on fits how the mod is meant to be used.^[1]

Unverified The sources don't say what spark's default for backgroundProfiler is, so we can't confirm whether the pack changed it. They also don't say exactly what the option does beyond its name.

The header entry

The file also contains _header. It's only a note pointing you to spark's configuration documentation, and it doesn't change any behavior.^[6]

FTB StoneBlock 4 1.21.0 ships with spark 1.10.124, using the NeoForge build of the mod. spark has been in the pack since FTB StoneBlock 4 1.0.0 or earlier, so it isn't a recent addition.^[2]

spark 1.10.124

This is a backport release. The build was manually uploaded to bring some bug fixes to the popular 1.21.1 version of Minecraft. It carries the latest spark for Minecraft 1.21.4 over to Modrinth. The full list of changes is on spark's own changelog page.^[7]

Unverified No pack changelog entries for spark were available, so changes to the mod between individual StoneBlock 4 releases can't be confirmed here.