spark in All the Mods 11

spark is a performance profiler for Minecraft clients, servers and proxies. If your world lags, your tick rate drops or your RAM disappears, this is the tool that helps you find out why. It is a diagnostic tool and adds no blocks or items to play with.^[1]

The pack ships spark 1.10.173 as the NeoForge build. It has been in the pack since All the Mods 11 0.0.1 or earlier.^[2]

What spark does

spark is made up of three separate components: a CPU profiler, memory inspection and server health reporting.^[1]

• CPU profiler: diagnoses performance issues such as lag, low tick rate and high CPU usage. It is lightweight, needs no setup, and running it for about 30 seconds is enough to give useful insights. It samples system activity, builds a call graph from the data and shows it in an online viewer.^[1]
• Memory inspection: a heap summary for a basic snapshot of memory, a heap dump for a full snapshot you can open in conventional analysis tools, and garbage collection monitoring so you can relate GC activity to hangs.^[1]
• Server health reporting: tracks TPS, tick durations, CPU usage, memory usage and disk usage. It can also monitor individual ticks and send a report whenever a single tick takes longer than a threshold you choose.^[1]

The profiler has two engines. One uses native AsyncGetCallTrace and perf_events through async-profiler, and only works on Linux x86_64 systems. The other is the built-in Java ThreadMXBean engine.^[1]

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

spark is different from most mods you'll meet in this pack: there's nothing to craft and no machine to place. It's a performance profiler for Minecraft clients, servers and proxies, so it helps you find out why the game is lagging.^[1]

The mod page says spark needs no configuration or setup, you just install it. That makes your first steps more about knowing what it can do than building anything.^[1]

What you can do with it

1. Start with the CPU profiler when you notice lag, a low tick rate or high CPU usage. Those are the problems it's meant to diagnose.^[1]
2. Let the profiler run for about 30 seconds. The mod page says that's enough to give useful insight into the problem areas.^[1]
3. Read the results as a call graph. spark samples what the system is doing, builds the graph from that, and shows it in an online viewer for you to analyse.^[1]
4. Check overall health. spark can report TPS, tick durations (min, max and average), CPU usage, memory usage and disk usage.^[1]
5. If you suspect a memory problem, use the memory tools: a heap summary, a full heap dump, and garbage collection monitoring.^[1]

The mod page also mentions a /tps command for checking ticks per second more accurately. It is the only command named in the sources I have.^[1]

Unverified This section describes spark as its project page does. The sources I have show no pack-specific changes, extra commands or permission settings for spark in this pack, so check in-game before relying on any of those.

Same as in the All the Mods 10 8.1 guide

Here's the thing about spark: it isn't a tech or machine mod. There are no machines, multiblocks, power networks, fluid pipes or item automation to set up. It's a performance profiler for Minecraft clients, servers and proxies, so "core mechanics" here means the diagnostic tools it gives you.^[1]

The sources also don't list any items or crafting recipes for it, so you won't be crafting anything with this mod.^[1]

The three components

• CPU Profiler: diagnoses performance issues such as lag, low tick rate and high CPU usage.^[1]
• Memory Inspection: diagnoses memory issues.^[1]
• Server Health Reporting: keeps track of overall server health.^[1]

How the CPU profiler works

The profiler samples statistical data about system activity and builds 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]

It's described as lightweight enough to run in production with minimal impact. Running it for just about 30 seconds is enough to give useful insight into problem areas. You can also tune it to target specific threads, sample at a specific interval, or record only "laggy" periods.^[1]

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

Memory tools

• Heap Summary: a basic snapshot of the JVM's heap, showing memory usage and instance counts for each class. It isn't meant to replace proper memory analysis tools.^[1]
• Heap Dump: a full HPROF snapshot of the server's memory, optionally compressed, which you can open in conventional analysis tools.^[1]
• GC Monitoring: watches garbage collection activity so you can relate it to server hangs, see how long collections take and how much memory they free, and compare young and old generation collections to help choose GC tuning flags.^[1]

Server health reporting

spark can report TPS (ticks per second, to a more accurate degree than the /tps command), tick durations (min, max and average), CPU usage for the server process and the overall system, memory usage, and disk usage.^[1]

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

Configuration in this pack

The pack sets backgroundProfiler to false in its spark config file. The file's header _header points to spark's own configuration documentation.^[3]

Unverified What the backgroundProfiler option does in detail isn't explained in the available sources, so check spark's official configuration documentation before relying on it.

Same as in the All the Mods 10 8.1 guide

Good news: spark is a simple one to configure. It's a performance profiler for clients, servers and proxies, and the project describes its CPU profiler as needing no configuration or setup, so you can just install it and go. This pack's config file is tiny.^[1][3]

What the pack sets

• backgroundProfiler is set to false in this pack. It is the only setting in the file.^[3]
• _header is just a text note at the top of the file that points to spark's configuration documentation. It doesn't change any behavior.^[3]

This pack, All the Mods 11 0.8.0-beta, ships spark 1.10.173 (the NeoForge jar). spark has been in the pack since All the Mods 11 0.0.1 or earlier, so it's one of the long-standing inclusions.^[2]

Recent spark releases

• 1.10.173: the latest version of spark for Minecraft 26.2. This is the version in the current pack.^[2][4]
• 1.10.172: the latest version of spark for Minecraft 26.1.^[5]

The mod's changelog entries for both releases only say that they bring the latest spark build for that Minecraft version, and point to the full changelog on the spark website. They don't list individual fixes or features, so I can't tell you what changed inside these builds.^[4][5]

There are also no pack changelog entries for spark available, so I can't say when the pack moved between spark versions beyond the current one.^[2]