Loop and child query activities that need initializing with meta info, do so by serializing that info from the master.
There was an assumption that that info. was not dynamic apart from in the case of some disk based input activities.
Even then, the initialization process was not well defined.
In the case seen here a keyed join had a dynamic filename and was dependent on onStart being called. It hand't and it caused the thor master to crash.
In other cases found, the activity could be initialized once but not reinitialized.
Original description of problem:
We have a complex LOOP script that runs successfully on Roxie and HThor, but is failing on Thor with the following error:
"Failed to receive reply from thor"
This gives the IP address of the Thor Master.
We've been unable to generate a concise, simple script to reproduce this error for troubleshooting.
However, we've heard that LOOP had problems like this in early HPCC versions, on Thor, even when the same logic worked fine on Roxie and Hthor.