Export results gives no feedback (and it can take a while if there are many results)

[smathot]

I just collected a large amount of data, that is, about 600 entries of 120 trials each, with many variables per trial. If I choose Export results → All in JATOS, nothing seems to happen for a long while (say 30 s). It does work, and in the end a merged data file is downloaded. But it would be better if there was some visual indication of JATOS working in the meanwhile to avoid people from thinking that JATOS has frozen.

[kristian-lange]

I agree completely, JATOS should indicate that it is downloading something or preparing a download, (similar to how JATOS handles study uploads).

Another related issue (#159) is that JATOS uses a lot of memory assembling the result data. It first loads all result data into memory and only then sends them to the client. This can lead lead to out-of-memory errors if the result data are big and/or numerous and the server has limited memory.

Both issues can be fixed together. Although right now JATOS has a feature-freeze until the ASSC conference is over, which will be in the end of June. Then it will be the first thing I will do.

[kristian-lange]

Added streaming of result data with chunked HTTP response and on the server side only one result is loaded from the DB at the time. This reduces memory consumption and prevents crashing the JVM.
Additionally JATOS UI gives feedback while downloading the results, so users wont get confused if it takes longer.
Will be part in next release (not sure yet if it's called 3.3.7 or 3.4).