Unable to view logs through ui for certain derivations

[brendanhay]

Certain derivations (possibly with colourised output) cause the Web UI's Log tab to lock up using 100% CPU and in most cases prompt for the tab/process to be killed.

Example: https://hercules-ci.com/accounts/github/urbit/derivations/%2Fnix%2Fstore%2Fl4zbls1g6dip502x4vfwinicpk9k0y33-vim-8.2.1522.drv/log?via-job=5eb98f0a-a71e-43bc-9e2c-c191558fb9f7

Occurs in both Firefox 80.0.1 + Google Chrome (85.0.4183.102) on Linux.

[roberth]

This appears to be caused by particularly long logs. The log tab needs some optimization or special casing.
As a workaround in the meanwhile, you could nix-store -l /nix/store/... on the agent to get the log.