When adding a task consisting of somewhere between 6-10k jobs, the server crashes. The total task description message size was 4.5MB, so it's possible this limit will be lower if your job descriptions are large.
There are 2 possible places that might have caused the excessive memory use:
1) XFire message processing
2) JobServer message parsing
Possible solutions:
- increase Java heap size
- investigate gzipping the task description message