spark is a performance profiling plugin based on sk89q's WarmRoast profiler
spark is made up of a number of components, each detailed separately below.
| CPU Profiler | Memory Inspection | Server Health Reporting |
|---|---|---|
| Diagnose performance issues with your server. | Diagnose memory issues with your server. | Keep track of your servers overall health. |
spark's CPU profiler is an improved version of the popular WarmRoast profiler by sk89q. It can be used to diagnose performance issues ("lag", low tick rate, etc).
It is:
- Lightweight - can be ran on production servers with minimal impact.
- Easy to use - no configuration or setup necessary, just install the plugin.
- 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.
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
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.
For a comparison between spark, WarmRoast, Minecraft timings and other profiles, see this page on the spark wiki.
spark is a fork of WarmRoast, which is licensed under the GNU General Public License.
Therefore, spark is also licensed under the GNU General Public License.