Datasets with large number of files failed to Re-index v6.4

[bikramj]

What steps does it take to reproduce the issue?
We recently upgraded to v6.4 and Re-indexing got stuck 3-4 times on 2 different datasets which are really huge. We run re-index on a separate server which is not part of Production workload. While re-indexing was stuck Payara server got stuck too and app was unavailable. It ran for hours and 1 time Payara server crashed and restarted with OutofMemory error and other time Payara server did not come back after crash.
I had to manually set indextime of these 2 datasets in DB to proceed with Re-index of other datasets. Last time on 6.2 upgrade it took a while to re-index but we did not run into issue with frozen server.

First dataset has 1057 files with size 321G on disk
Second dataset 2872 files with 84G size

• When does this issue occur?
  while Re-indexing bug datasets

• Which page(s) does it occurs on?

• What happens?
  Payara server hangs and stop responding

• To whom does it occur (all users, curators, superusers)?
  All users

• What did you expect to happen?
  Complete the re-indexing

Which version of Dataverse are you using?
6.4