'Gather' on tall array lasts forever

I am running R2017a on Windows 10, and using a tall array that was constructed off a Datastore object (that was, itself, constructed from tall arrays built on MATLAB matrices of doubles).

What really bugs me about the issue I'm having now is that all my code used to work fine. One day it simply started hanging when I tried to run it.

This is the block in question:

%load

tallTraindat = tall(datastore);

sz = size(tallTraindat);

sz = gather(sz);

numExamples = sz(1);

exampleLen = sz(2);

As you can see, this is about as vanilla as it gets. But the operation 'sz = gather(sz)' simply hangs forever. It never finishes or returns. My parallel pool has started properly, and the gather operation gets to the point where it prints 'Evaluation 100% complete'. But it goes nowhere from there. If I pause execution, I'm always taken to a point in RemoteSpdmExecutor, line 129 'obj.RemoteSpmdController.drainIO( false );'. This line apparently lasts forever.

Tearing my hair out over this one. If anyone even has a suspicion where to look for the source of this problem, I'd appreciate it. I'll try to respond quickly to requests for more info.

Answer 1

[Sharan Paramasivam Murugesan]

Validate your cluster profile. Refer to the documentation link for details: https://www.mathworks.com/help/distcomp/discover-clusters-and-use-cluster-profiles.html#brrzq8d-1

If the validation fails, then there is a problem with the installation and you have to contact our installation team for more help.

If the validation passes, then provide more details as to what changes happened in your machine (e.g., any OS update/MATLAB update) since it started hanging.