StressBotPlugin

Server stress testing plugin that spawns fake players with random equipment for performance testing

Server stress testing plugin that spawns configurable numbers of fake player bots with randomized equipment to test viewport performance, rendering systems, and server load under heavy player density.

File Location

GameServer/Data/Plugins/StressBotPlugin.xml

Dependencies

Depends On	Purpose
Item.xml	Equipment pool loaded from Item.xml to randomize bot equipment

Overview

StressBotPlugin creates "stress bots" - fake players that appear in the game world with fully randomized equipment and character classes. These bots are visible to real players and generate all the same viewport packets, rendering effects, and server processing as real players, making them ideal for:

• Testing server performance under high player density

• Stress testing viewport packet processing

• Testing client rendering performance with many players

• Validating equipment visual effects at scale

• Performance profiling under realistic load

GM Commands

All commands require GM authority level 32 or higher.

Command	Description
/stressbot spawn <map> <count>	Spawn specified number of bots on a map
/stressbot clear <map>	Remove all bots from specified map
/stressbot clearall	Remove all bots from all maps
/stressbot status	Display current bot counts per map
/stressbot reload	Reload configuration from XML

Command Examples

/stressbot spawn 0 100       - Spawn 100 bots in Lorencia
/stressbot spawn 2 50        - Spawn 50 bots in Devias
/stressbot clear 0           - Remove all bots from Lorencia
/stressbot clearall          - Remove all bots from all maps
/stressbot status            - Show current bot distribution

Configuration Attributes

Core Settings

Attribute	Type	Default	Description
Enabled	bool	false	Enable/disable the plugin. Set to true to activate stress testing features

Bot Limits

Attribute	Type	Default	Description
MaxBotsPerMap	int	200	Maximum number of bots allowed per map. Higher values create more concentrated stress. Limited by server memory (~50KB per bot)
MaxBotsTotal	int	500	Maximum total bots across all maps. Limited by server's summon object pool (1000 slots total, range 15000-15999, shared with player pets and guardians)

Bot Appearance

Attribute	Type	Default	Description
DefaultBotLevel	int	400	Level assigned to spawned bots. Affects visual appearance through armor glow effects and animations. Higher levels display more advanced visual effects
DefaultBotClass	int	1	Default character class when RandomizeClass="false". Values: 0=Dark Wizard, 1=Dark Knight, 2=Fairy Elf, 3=Magic Gladiator, 4=Dark Lord, 5=Summoner, 6=Rage Fighter
RandomizeClass	bool	true	If true, each bot receives a random class (0-6). Creates visual variety for more realistic testing scenarios

Equipment Settings

Attribute	Type	Default	Description
RandomizeEquipment	bool	true	If true, equips bots with random items from Item.xml. Tests equipment rendering, glow effects, and visual system performance
RandomizeWings	bool	true	If true, includes wings in equipment randomization. Wings have high-impact particle effects and should be tested separately
ItemLevel	int	13	Item level for equipped items (0-15). Higher levels = more visual effects (glow, particles). Level 13+ creates significant visual complexity
ItemOption	int	16	Additional option level (+4, +8, +12, +16). Value represents the actual bonus. Adds stat display effects and visual indicators
ItemExcellent	bool	true	Add excellent options to items. Excellent items have special glow effects and are the most visually intensive item type

Spawn Behavior

Attribute	Type	Default	Description
WalkableRetryCount	int	50	Number of random position attempts before fallback. Higher values = better spatial distribution but slower spawn time. 50 is typically sufficient for most maps

Important Behavior

Bot Spawning Algorithm: Bots attempt to spawn near the GM who issued the spawn command (within 15 tile radius). If no walkable position is found nearby, the system falls back to random map positions, and finally to the map center area (coordinates 100-156).

Memory Usage: Each bot consumes approximately 100KB+ of memory for OBJECTSTRUCT, inventory arrays (237 slots), InventoryMap, and equipment data. Spawning 1000 bots requires ~100MB+ RAM. Monitor server memory usage during testing.

Viewport Complexity: Viewport updates are O(n²) complexity. Each player sees all nearby players, so 100 bots in one area generates 10,000 viewport update calculations. Start with 50-100 bots and increase gradually.

Item Pool Loading: The plugin reads Item.xml on initialization and builds separate pools for regular equipment (slots 0-6) and wings (slot 7). Only items with valid slot assignments are included in randomization.

Bot Safety: Bots are configured with extremely high Life (30,000), Defense (32,000), and MagicDefense (32,000) to prevent death during testing. Bot death can cause server crashes as they don't have full player cleanup handlers.

Cleanup Required: Always use /stressbot clearall when finished testing. Leaving bots active consumes summon slots that would normally be available for players' pets and summons.

Common Map Numbers

Map ID	Map Name	Map ID	Map Name
0	Lorencia	30	Castle Siege
1	Dungeon	31	Land of Trials
2	Devias	33	Aida
3	Noria	34	Crywolf
4	Lost Tower	51	Elbeland
7	Atlans	56	Swamp of Calmness
8	Tarkan	57	Raklion
10	Icarus

Examples

Development Testing

<StressBotPlugin
    Enabled="true"
    MaxBotsPerMap="100"
    MaxBotsTotal="200"
    DefaultBotLevel="400"
    DefaultBotClass="1"
    RandomizeClass="true"
    RandomizeEquipment="true"
    RandomizeWings="true"
    ItemLevel="13"
    ItemOption="16"
    ItemExcellent="true"
    WalkableRetryCount="50"
>

Conservative settings for development testing. 100 bots per map, full equipment randomization for visual testing.

High Stress Test

Uniform Testing

Wings Only Test

Performance Testing Workflow

1. Baseline Test

/stressbot spawn 0 50

Start with 50 bots in Lorencia. Check server CPU, memory, and client FPS.

2. Incremental Load

/stressbot spawn 0 50    (50 total)
/stressbot spawn 0 50    (100 total)
/stressbot spawn 0 50    (150 total)

Incrementally add bots to find performance thresholds.

3. Multi-Map Distribution

/stressbot spawn 0 100   (Lorencia)
/stressbot spawn 2 100   (Devias)
/stressbot spawn 3 100   (Noria)

Test server performance with load distributed across multiple maps.

4. Status Monitoring

/stressbot status

Regularly check bot distribution and ensure limits aren't exceeded.

5. Cleanup

/stressbot clearall

Always clear bots when testing is complete to free server resources.

Common Issues

Issue: Bots fail to spawn (message shows "X failed")

Causes:

• Map has limited walkable space (increase WalkableRetryCount)

• Summon object pool exhausted (clear existing bots or reduce MaxBotsTotal)

• Invalid map number (check Map ID table)

Solution: Use /stressbot status to check current bot count, clear existing bots, or try a different map with more open space.

Issue: Server performance degrades severely

Causes:

• Too many bots in one viewport area (O(n²) packet processing)

• High ItemLevel/Excellent items creating excessive particle effects

• Client machine limitations (not server issue)

Solution: Reduce bot count, disable equipment randomization, or distribute bots across multiple maps. Monitor both server CPU and client FPS separately.

Issue: Bots disappear after server restart

Behavior: This is expected. Stress bots are not saved to the database. They exist only in server memory and are cleared on restart.

Solution: Re-spawn bots after restart using /stressbot spawn commands.

Issue: Cannot spawn more bots despite being under limits

Cause: Server's summon object pool is shared with player pets, guardians, and other summons. The pool has exactly 1000 slots (object indices 15000-15999 in normal servers, less in Castle Siege mode).

Solution: Clear existing bots (/stressbot clearall), or ask players to unsummon pets/guardians temporarily. Check active summon count with /stressbot status.

Tip: For viewport stress testing, spawn all bots in a small area (they spawn near the GM). For distributed load testing, teleport to different locations before each /stressbot spawn command.

Technical Details

Bot Properties

Stress bots are configured as follows:

• Type: OBJECT_BOTS (appears in viewport, minimal server processing)

• Life/Mana: 30,000 (prevents death)

• Defense: 32,000 (monsters cannot damage them)

• MagicDefense: 32,000 (magic attacks cannot damage them)

• Level: Configurable (affects visual appearance)

• Name: Bot##### where ##### is object index (e.g., "Bot15450")

• Inventory: Full inventory array allocated (237 slots including equipment, InventoryMap arrays)

• Movement: Stationary (no AI, no walking)

• Combat: Cannot attack, cannot be killed

Slot Assignment

Equipment slots match MU Online's standard layout:

Slot	Name	Slot	Name
0	Weapon (Right)	5	Gloves
1	Weapon (Left)	6	Boots
2	Helm	7	Wings
3	Armor	8	Pet
4	Pants

When RandomizeEquipment="true", slots 0-6 are filled with random items from the Item.xml pool that match each slot. Wings (slot 7) are only equipped if RandomizeWings="true".

Item Excellent Options

When ItemExcellent="true", bots receive 0x3F (all 6 excellent options):

• Excellent items display special glow effects

• This creates maximum visual complexity for stress testing

• Performance impact is significant with 100+ bots

Set to false for baseline testing without excellent effects.