GUI takes a while to load

[iche033]

Environment

• OS Version: 24.04
• Source or binary build?
  source build, all jetty branches

Description

• Expected behavior: Gazebo GUI takes reasonable amount of time to startup
• Actual behavior: GUI can take >1min to load and show the world in the 3D window

One observation is that the server (and the physics system) loads fast (~ a few seconds) but the GUI (GuiRunner) takes a while to process the initial state. The rendering also take a while to load and create all the mesh (which is expected but could be improved)

Some rough numbers from my machine (Intel Core i7-6800K CPU @ 3.40GHz, 32GB RAM):

• server (physics): ~10 seconds
• client (gui + rendering): 1 min

Steps to reproduce

1. gz sim -v 4 jetty.sdf

[iche033]

Found the root cause of the issue to be model sdf deserialization. There is a ticket upstream in sdformat: gazebosim/sdformat#1478

This is also affecting sim when the Play button is pressed. When changing from paused to play state, the GUI makes a WorldControlState request that sends a copy of its ECM to the server. The server then calls SetState which goes through all components and deserialize them.