Hang after too many gl requests in Docker

From the tests documented starting at https://github.com/plotly/streambed/issues/9865#issuecomment-349995119:

When image-exporter is run as an imageserver in Docker, after a small number of gl requests (30-40), the image-exporter hangs completely. The request in progress times out, and the server won’t accept any more connections and must be restarted.

Two examples:

• If test/image-make_baseline.js is used to run gl*, it hangs at gl3d_chrisp-nan-1.json.
• If test/image-make_baseline.js is used to run gl3d*, it makes it past gl3d_chrisp-nan-1.json and hangs at gl3d_snowden_altered.json.

This means that the issue is unlikely to be specific to any one plot, but rather some resource becomes exhausted or something builds up to the point where image generation can’t proceed.

@etpinard @monfera FYI

[etpinard]

Oh I should mention. I tried running the gl image tests in docker without the ignore-gpu-blacklist flag yesterday:. Without that flag the gl images fail to generate.

[scjody]

@monfera @etpinard I’ve added some debugging stuff to the Docker container in #44.

• Xvfb runs with X errors sent to STDOUT (instead of being ignored), and auditing is turned on. This means it prints a message for every X connection and disconnection, which shows if Electron is connecting and disconnecting (spoiler alert: it isn’t).
• Xvfb’s screen dimensions have been doubled.
• I added a VNC server, window manager, and a wrapper script.

Usage:

• Build the image (docker build -f deployment/Dockerfile -t isdebug .), or grab it from quay.
• Run the image as container isdebug and expose the VNC and imageserver ports: docker rm -f isdebug ; docker run -p 9091:9091 -p 5900:5900 --name isdebug -ti isdebug
• From a second window, connect and run the VNC wrapper: docker exec -ti isdebug /vnc
• Connect to the VNC display localhost:0 using your favourite client, such as gvncviewer on Ubuntu or Chicken of the VNC on OS X.
• From a third window, run whatever tests are needed, such as (in the plotly.js repo): node test/image/make_baseline.js gl* (you’ll want to modify testContainerUrl in tasks/util/constants.js, like in https://github.com/plotly/plotly.js/tree/image-exporter-testing)

In my case the image exporter window where the work was occurring was in fluxbox tab 2. Some errors were printed during normal operation (at this point images were being generated successfully):

When the server hung, a different message was printed:

I have not had the chance to investigate the significance of either of these things.