ParallelTable: How to see which cells finished calculating?

Question

I have a code to generate a table with a computationally very expensive function f[x,y]. I run the code on a cloud server, that is, from the command line without graphical output. I found a way to print to the terminal the parameters x and y before a cell is computed. However, unfortunately, I now see that my code got stuck computing one of many cells and just by knowing which cells were started I don't know which of those have actually finished successfully (and, in particular, which ones have not).

Here is my code so far:

tab = Block[{counter},
   SetSharedVariable[counter];
   ParallelTable[
    counter++;
    Print[{counter, (arg[[1]]), 10^21 (arg[[2]])}];
    {arg[[1]], arg[[2]], f[arg[[1]], arg[[2]]]}, {arg, 
     Tuples[{Range[0, 2, 0.1], Range[0, 4, 0.1]}]}, 
    Method -> "FinestGrained"]];

I assume that there is no way for me to recover the already computed cells. But at least I want to be smarter next time and print some information once the cell finished computing. I am aware that I could add this command at the end of the function f. But is there also a way to include this kind of progress indicator in the ParallelTable body?

Answer 1

I found the solution to this issue myself: Storing the result temporarily in a variable, then printing the message, and then setting the array element to the value of the variable:

f[x_, y_] := Block[{}, Pause[2]; Return[x + y]];
tab = Block[{counter = 0, result},
   SetSharedVariable[counter];
   ParallelTable[counter++;
    Print[{counter, arg[[1]], arg[[2]]}];
    {arg[[1]], arg[[2]], result = f[arg[[1]], arg[[2]]]; 
     Print["done with ", {counter, arg[[1]], arg[[2]], result}]; 
     result}, {arg, Tuples[{Range[0, 2, 1], Range[0, 4, 1]}]}, 
    Method -> "FinestGrained"]];