Mesecons Debug Collection

Throttles mesecons if the server is lagging, in particular when mesecons is causing the lag.

Overview

This mod can penalizes mesecons activity on a per-mapblock basis, which can help laggy or machine-heavy servers to be less laggy overall. Penalties are implemented as delays on various events.

Lag and per-mapblock mesecons usage are tracked over time, in order to calculate how much to penalize each mapblock, or whether to reduce the penalty.

The mod defines 3 regimes of lag, with different scales of penalties.

• If the server steps are not taking much longer than the time allotted for them, the "low penalty" regime will apply.
• If the server steps are taking too long on average, and mesecons usage isn't particularly high, the "medium penalty" regime will apply.
• If the server steps are taking too long on average and mesecons usage is high, or the server steps are taking much too long to execute, the "high penalty" regime will apply.

Each of these regimes has an associated "scale" and "offset". Every time the penalties are re-evaluated, they are changed according to this formula:

    new_penalty = old_penalty + (relative_load * penalty_scale) + penalty_offset

Here, relative_load is the ratio of how much time the current mapblock spends doing mesecons, to the mean time (spent doing mesecons) across all mapblocks currently running mesecons. This value is currently clamped between 0.1 and 10, to prevent certain edge cases from being penalized too rapidly. A value of 10 would mean that the mapblock under consideration is using 10x as much mesecons as the average mapblock.

Note that, depending on the values of penalty_scale and penalty_offset, the new penalty may be less than the old penalty. This is to allow penalties to reach equilibrium under a constant load, and to taper off over time if the usage in the mapblock declines, or the regime changes.

Settings

• penalty_clear_cooldown = 120 Seconds that a player has to wait between using the mesecons_clear_penalty command
• max_penalty = 120 Upper limit of the per-mapblock penalty
• penalty_mapblock_disabled = 110 Completely disable mesecons in a mapblock, if the penalty exceeds this value. Set above max_penalty to disable this feature.
• penalty_check_steps = 50 # of server steps between updating the penalties
• gc_interval = 61 Seconds after which data about unloaded mapblocks is removed from memory.
• hud_refresh_interval = 1 Seconds between updating the client's HUD
• moderate_lag_ratio = 3 Ratio between actual and expected length of a server step at which lag is considered "moderate"
• high_lag_ratio = 9 Ratio between actual and expected length of a server step at which lag is considered "high"
• high_load_threshold = 0.33 % of processing a server spends on mesecons at which the mescons load is considered "high".
• low_penalty_offset = -1 Offset of the penalty in the low-lag regime.
• low_penalty_scale = 0.1 Scale of the penalty in the low-lag regime. The default values ensure that nothing is penalized in the low-lag regime.
• medium_penalty_offset = -0.8 Offset of the penalty in the moderate-lag regime.
• medium_penalty_scale = 0.2 Scale of the penalty in the moderate-lag regime.
• high_penalty_offset = -0.5 Offset of the penalty in the high-lag regime.
• high_penalty_scale = 0.5 Scale of the penalty in the high-lag regime.

Privs

• mesecons_debug Allows execution of mesecon debug chatcommands

Commands

• /mesecons_clear_penalty Clears the penalty for the current mapblock. Users can only execute this every penalty_clear_cooldown seconds
• /mesecons_global_stats shows the mapblock with the most prominent usage of mesecons activity
• /mesecons_hud toggles the hud
• /mesecons_stats shows some mesecons stats for the current position

Admin Commands

All of these commands require the mesecons_debug privilege.

• /create_lag <microseconds> <chance> Artificially slow down the server by microseconds every chance server steps. Useful for debugging this mod.
• /mesecons_debug_get <setting> Inspect the current value of a setting.
• /mesecons_debug_set <setting> <value> Change a setting value. This does not save the value between reboots!
• /mesecons_disable Disables mesecons entirely
• /mesecons_enable Undoes the above command
• /mesecons_flush Flushes the mesecons action queue
• /mesecons_whitelist_add adds the current mapblock to the whitelist
• /mesecons_whitelist_get shows the list of whitelisted mapblocks
• /mesecons_whitelist_remove removes the current mapblock from the whitelist

Nodes

Mesecons Lagger

A node which can create n microseconds of lag once every chance server steps. Useful for debugging this mod.

Penalty Controller

Requires the digiline mod.

Can query the penalty and usage values of the mapblock it is placed in.

Example code to query it with the luacontroller:

if event.type == "program" then
  digiline_send("penalty_ctrl", "GET")
end

if event.type == "digiline" and event.channel == "penalty_ctrl" then
  --[[
  event.msg = {
    micros     = 0, -- micros_per_second
    avg_micros = 0, -- avg_micros_per_second
    penalty    = 0, -- in seconds
    whitelisted = false
  }
  --]]
end

License

• CODE:

  • MIT

• textures/penalty_controller_top.png

  • CC BY-SA 3.0 https://cheapiesystems.com/git/digistuff