Diagnosing Minecraft Server Lag Using Spark
Lag can ruin the player experience on your Minecraft server. Whether it’s a consistent delay or sudden spikes, diagnosing the cause is crucial for a smooth gaming environment. Spark, a performance profiling plugin, provides powerful tools to identify and resolve lag issues. This guide explains how to use Spark to diagnose lag spikes.

Understanding Lag Spikes
Lag spikes occur when one or a few game ticks take significantly longer than average to execute. They might: 

 

 

 Happen frequently (e.g., once every 20 ticks). 

 Occur rarely (e.g., once every minute). 

 Be tied to specific player actions or server events. 

 

 

 Lag spikes can be challenging to diagnose because typical profiling averages out the data, masking the spikes. However, Spark offers tools like /spark tickmonitor and /spark profiler to pinpoint these issues effectively.

Installing Spark
If you’re running PaperMC for 1.21 or later, Spark is already built in , and you do not need to install it separately. For all other server types or older versions, you’ll need to install Spark manually. 

 Installing Spark on Non-PaperMC Servers 

 

 

 

 Download Spark 

 

 Visit the Spark Website . 

 Download the latest version of Spark for your server type (e.g., .jar file for Paper, Spigot, or Bukkit). 

 

 

 

 Place Spark in Your Server’s Plugins Folder 

 

 Upload the downloaded spark-x.x.x.jar file to the /plugins folder of your server directory. 

 

 

 

 Restart the Server 

 

 Restart your Minecraft server to load the Spark plugin. 

 

 

 

 Verify the Installation 

 

 Once the server is running, use the /spark command in the server console or chat to verify the installation.

 

 

 Run: 

 /spark 

You should see Spark’s command list and version details.

Use /spark tickmonitor to Detect Lag Spikes
What Does  /spark tickmonitor Do? 

 This command tracks tick execution time and highlights spikes by comparing individual ticks against the server’s average tick duration. 

 How to Use It 

 

 

 

 Enable Monitoring Run: 

 /spark tickmonitor 

 

 By default, Spark will report ticks that take 100% longer than the average. 

 

 

 Set a Custom Threshold You can use an absolute tick duration threshold. For example: 

 /spark tickmonitor --threshold-tick 50 

 

 This will report any tick exceeding 50 milliseconds. 

 

 

 Observe Gameplay 

 

 Wait for a lag spike to occur. 

 Note the in-game effects during the spike and correlate them with the monitoring output in chat. 

 

 

 

 Adjust Sensitivity if Needed If no spikes are detected, lower the threshold: 

 /spark tickmonitor --threshold-tick 70 

 

 

 

 

 Example 

 If a WorldEdit action creates a spike, you might see ticks reported with over 1000% increases in duration.

Profile Laggy Ticks Using /spark profiler
What Does /spark profiler Do? 

 The /spark profiler command captures detailed performance data. With the --only-ticks-over option, you can filter the profile to include only laggy ticks. 

 How to Use It 

 

 

 

 Choose a Threshold Use the tick duration from Step 1 as a reference. For example, if laggy ticks exceed 150 milliseconds: 

 /spark profiler --only-ticks-over 150 

 

 

 

 Run the Profiler 

 

 The profiler will start recording, but only for ticks exceeding the threshold. 

 Let it run long enough to capture lag events. 

 

 

 

 Stop the Profiler Use: 

 /spark profiler stop 

 

 

 

 Inspect the Results Open the profiling report and analyze the data. The laggy ticks will stand out, making it easier to identify the cause. 

 

 

 

 Example 

 In the profiler output, you might see a high percentage of time spent on a plugin, mod, or player action. This helps isolate the problem.

Common Causes of Lag Spikes
Heavy Plugin Tasks 

 

 Plugins like WorldEdit, if used on large areas, can cause spikes. 

 Identify such plugins in the profiler and adjust their usage or settings. 

 

 

 

 Inefficient Mods or Data Packs 

 

 Look for mods causing high execution times. 

 Update or replace inefficient mods. 

 

 

 

 Resource Overload 

 

 Large numbers of entities or block updates can cause spikes. 

 Use tools like /kill @e[type=!player] carefully to manage entities. 

 

 

 

 

 Conclusion 

 Using Spark’s tools, you can efficiently diagnose and address lag spikes on your Minecraft server. The combination of /spark tickmonitor for detection and /spark profiler for detailed analysis ensures you can pinpoint and resolve performance issues quickly. 

 For further assistance or advanced optimization, consult the Spark documentation . 

 

 Additional Help 

 If you encounter any issues or need further assistance, open a support ticket via the Billing Area . Our support team is ready to assist you.