add threading to datahub's export #1254
Description
Current Implementation and Limitations
When you click on export in the datahub it starts to assemble your file in the current window (without giving you any UI feedback). If you leave the page and navigate elsewhere in ODC t the export dies. Exporting can take several minutes so the current implement isn't sufficient.
Associated Application Components
Client, Server
Proposed Solution
You need to use threading for downloads. At the very least, I would use at least 1 thread that manages export. You can also use several threads to assemble very large datasets if you want and create a bunch of temporary files and then merge them at the end if you want to speed things up (but you probably would want to have some logic to decide how many threads you need according to what is being asked for / how many records exist).
You also need to add some visual feedback to the user that the exporting process has begun and that a download popup will appear when the data is ready.
Estimated Difficulty
Medium
Priority
High