Could we run the npm install when the tests runs? So during the current test, we prepare/install what's needed for the next test

This is the path I tested in this spike. I created a test Jenkins agent (integration-agent-docker-9999) with the same setup as we have in CI to be able to make sure I get reliable metrics out of it. I tried running the change alone on the server and with two other jobs running (quibble-with-gated-extensions-selenium-php83) at the same time on the same machine. The other two jobs runned in a loop on the server trying to simulate full load. I wanted to see if the change would impact the performance of the tests. I also picked four runs from Jenkins as a reference (52638, 52640, 52648, 52651).

Results

Summary

• prepare/install cuts the browser stage by 128 s (30 %) with the job alone and by 167 s (29 %) with three jobs on the agent. The build itself by 130 s and 169 s.
• The tests are not slower with a background install, in total or per project, in either scenario.
• The background install takes longer (214 s against 155 s alone, 371 s against 203 s under load) because it runs with nice 19 next to 7 wdio instances per job. It still finishes before its tests are due except for a few short suites, which is the 40 to 60 s the stage keeps above the test sum.
• I also did a test running 1 wdio test at a time (by mistake) not setting CI=true (wdio at one instance, tests 1.7x slower than production) and that gave the same saving in seconds: 128 s alone, 170 s under load.

Change #1335750 had a related patch set uploaded (by Phedenskog; author: Phedenskog):

[integration/quibble@master] Run the next npm install during the browser tests

https://gerrit.wikimedia.org/r/1335750

Change #1337439 had a related patch set uploaded (by Phedenskog; author: Phedenskog):

[integration/config@master] jjb: Overlap npm install with the gated browser tests

https://gerrit.wikimedia.org/r/1337439

Change #1335750 merged by jenkins-bot:

[integration/quibble@master] Run the next npm install during the browser tests

https://gerrit.wikimedia.org/r/1335750

Change #1337439 merged by jenkins-bot:

[integration/config@master] jjb: Overlap npm install with the gated browser tests

https://gerrit.wikimedia.org/r/1337439

Mentioned in SAL (#wikimedia-releng) [2026-09-09T09:42:15Z] <phedenskog> jjb: update quibble-with-gated-extensions-selenium-php83 to run npm install ahead of the browser tests T436376

I deployed this today. I can see that its faster but its hard to see yet how large the in is, probably smaller than I measured on the test agent. Let me check tomorrow when we have more data.