MCF Browser - Poor performance with larger files

[clincoln8]

The tool can currently handle up to 50 MB MCF files if local dcids do not need to be resolved. For unresolved MCF files, the limit is around 30 MB.

Every 30 seconds (only tested on Chrome) while loading in an mcf file, a popup appears stating that page is unresponsive. The user is prompted to 'Exit Page' or 'Wait'. This does not mean the application has crashed, it is just taking a long time to load the mcf file. Theoretically, waiting a long enough amount of time should load in the MCF, given local memory does not run out of space. For example, uploading the first 1,000,000 lines of this CovidMobility file from gs://resolved_mcf/CovidMobility/CovidMobility.mcf (resulting in 33MB) takes about 1.5minutes to load in which the user is prompted 3 times to choose between exiting and waiting. For a 100MB file, I waited about 17minutes for it to load, but it never loaded.

A related problem is that if the user navigates to another tab while a file is loading, the application is blank upon returning.

The tool would be significantly more useful if it could handle files up to 100 MB consistently. For now it can load up to 50MB within a reasonable amount of time.

I am not sure exactly how this problem can be solved. If the parsing can be done asynchronously or perhaps break the file into smaller sections and parse in parallel, that could speed it up.