If large files are getting created in a tmp directory all the time, or some of the time, it is because users execute long running reports that cause these files to get created in the temp directory. Even Query-based reporting, or QBR, can cause this to happen. However, this is by design. Generally speaking, Birt will clean up after itself.
It is only an issue once these large files start filling up the drive and the server runs out of space. Two known causes when these temp files do -not- get auto deleted:
1)a report hangs and never completes, then there is a chance that its temporary files won't be cleaned up
2)if users are running custom reports, the issue of temp files not getting cleaned up automatically can, definitely, occur, here is why:
"What causes these temp files to get created?
Normally, when users encounter this issue, it is due to long running custom reports (that are executed against a very large number of records).
....One option is to remove the inefficient custom reports from Maximo application to prevent this situation in the future. In addition, users will need to redesign these reports to make them more efficient and less data intensive"
Users can also redirect the temporary files to a different directory if they wish(if the current drive is insufficient and it runs out of disk space). That is described here:
This links to the feature guide for additional detail on the mxe.report.birt.tempfolder parameter as well as a java.io.tmpdir parameter the the user can set to force temporary files to a location of their choosing. This won't stop the creation of those files(as it is by design), but it gives the user some control over where they are created, and specify a larger drive for the files to be redirected to.
Lastly, these files can also be deleted, once Maximo stops writing to them, so that they do not fill up the disk space.