he hash can't be printed otherwise. It's a deep tree and just print'ing it would just give the top level keys...

I meant avoid the use of dump just temporarily to see if it is the cause of the memory growth.

If avoiding it fixed the immediate problem, then you could look for another way of recursively printing deep data structures that didn't suffer the same problem. Maybe Data::Dumper, or Data::Dump::Streamer or even rmap with a little logic of your own.

But first you need to track down the source of the problem. You could equally just comment out the print altogether.

Is %datahash shared?

What's in the hash doesn't matter.

There is no logic I know of for using local rather than my in threads.

Without sight of the full program (stick it on your scratchpad and /msg me if you don't want to post it), or a cut down but working version that demonstrates the same symptoms, it's really impossible to offer much in the way of help.