Skip to main content

front end - How to see Monitor temporary cell with ParallelSubmit?


I have a function to load large files into a "HSQL(Standalone)" database for processing that uses Monitor to update the interface on the progress and status of the upload.


loadBigFile[t_Integer?Positive, steps_Integer?Positive] :=
 Module[{stepProgress = 0},
  Monitor[
   While[stepProgress < steps,

    (* Read batch and load to db *)
    Pause[t];
    stepProgress += 1
    ],
   Column[{StringRiffle[ToString /@ {stepProgress, steps}, " of "],
     ProgressIndicator[stepProgress, {0, steps}]},
    Alignment -> Center]
   ];
  stepProgress
  ]


loadBigFile is just to demonstrate the issue.


loadBigFile[1, 10]
(* 10 *)

enter image description here


This process takes 30+ minutes to load each file. I would like to concurrently load these files to reduce the wait time by using ParallelSubmit.


k = LaunchKernels[2];
DistributeDefinitions[loadBigFile];
{f1, f2} = {ParallelSubmit[loadBigFile[1, 5]], ParallelSubmit[loadBigFile[1, 9]]}


enter image description here


When I execute WaitAll the EvaluationObjects do run concurrently. However, instead of a monitor temporary cell for each of them I get a front end error from each kernel they are running on.


WaitAll[{f1, f2}]
CloseKernels[k];

enter image description here


(* {5, 9} *)



FrontEndObject::notavail: A front end is not available; certain operations require a front end.



How do I get the monitor temporary cells to show in the notebook for each EvaluationObject running? Or is there another method I should use for concurrent execution with Monitor?



Answer



From the link in the comment above I have devised a solution included here for ParallelSubmit specific searches.


Monitor can not be used so I make a progress function that will assist with the visual status update.


progress[current_, total_] :=
 Column[{StringRiffle[ToString /@ {current, total}, " of "],
   ProgressIndicator[current, {0, total}]},
  Alignment -> Center]


I use a status Association to hold the status updates as it makes the code more readable than using a list as with other solutions. The loadBigFile function has to change slightly.


loadBigFile[t_Integer?Positive, steps_Integer?Positive] :=
 Module[{stepProgress = 0},
  status[[Key[$KernelID]]] = <|
    "File" -> "File " <> ToString@RandomInteger[100],
    "Monitor" -> progress[stepProgress, steps]
    |>;
  While[stepProgress < steps,
   (* Read batch and load to db *)

   Pause[t];
   stepProgress += 1;

   (* Update status *)
   status[[Key[$KernelID], "Monitor"]] = progress[stepProgress, steps];
   ];

  status[[Key[$KernelID], "File"]] = status[[Key[$KernelID], "File"]] <> " done.";
  stepProgress
  ]


The Keys of the Association are the $KernelID and each has a "File" and "Monitor" key. loadBigFile updates these as it progresses.


k = LaunchKernels[2];

status = Association @@ 
     ParallelTable[$KernelID -> <|"File" -> "", "Monitor" -> ""|>, {i, $KernelCount}]
(* <|43 -> <|"File" -> "", "Monitor" -> ""|>, 42 -> <|"File" -> "", "Monitor" -> ""|>|> *)

Distribute the definitions and variables


DistributeDefinitions[progress, loadBigFile];

SetSharedVariable[status];

ParallelSubmit the jobs.


{f1, f2} = {ParallelSubmit[loadBigFile[1, 5]], ParallelSubmit[loadBigFile[1, 9]]}

enter image description here


PrintTemporary with Dynamic is used instead of Monitor. This accesses the status association to display.


PrintTemporary[
  Dynamic[Row[
    Riffle[Column[#, Alignment -> Center] & /@ 

      Query[Values, Values]@Select[#"Monitor" =!= "" &]@status, Spacer[5]]]]];
WaitAll[{f1, f2}]

enter image description here


Both have status displayed and updated concurrently.


Clean up.


UnsetShared[progress, loadBigFile, status];
CloseKernels[k];

Hope this helps.



Comments

Post a Comment

Popular posts from this blog

functions - Get leading series expansion term?

Given a function f[x] , I would like to have a function leadingSeries that returns just the leading term in the series around x=0 . For example: leadingSeries[(1/x + 2)/(4 + 1/x^2 + x)] x and leadingSeries[(1/x + 2 + (1 - 1/x^3)/4)/(4 + x)] -(1/(16 x^3)) Is there such a function in Mathematica? Or maybe one can implement it efficiently? EDIT I finally went with the following implementation, based on Carl Woll 's answer: lds[ex_,x_]:=( (ex/.x->(x+O[x]^2))/.SeriesData[U_,Z_,L_List,Mi_,Ma_,De_]:>SeriesData[U,Z,{L[[1]]},Mi,Mi+1,De]//Quiet//Normal) The advantage is, that this one also properly works with functions whose leading term is a constant: lds[Exp[x],x] 1 Answer Update 1 Updated to eliminate SeriesData and to not return additional terms Perhaps you could use: leadingSeries[expr_, x_] := Normal[expr /. x->(x+O[x]^2) /. a_List :> Take[a, 1]] Then for your examples: leadingSeries[(1/x + 2)/(4 + 1/x^2 + x), x] leadingSeries[Exp[x], x] leadingSeries[(1/x + 2 + (1 - 1/x...
Post a Comment
Read more

mathematical optimization - Minimizing using indices, error: Part::pkspec1: The expression cannot be used as a part specification

I want to use Minimize where the variables to minimize are indices pointing into an array. Here a MWE that hopefully shows what my problem is. vars = u@# & /@ Range[3]; cons = Flatten@ { Table[(u[j] != #) & /@ vars[[j + 1 ;; -1]], {j, 1, 3 - 1}], 1 vec1 = {1, 2, 3}; vec2 = {1, 2, 3}; Minimize[{Total@((vec1[[#]] - vec2[[u[#]]])^2 & /@ Range[1, 3]), cons}, vars, Integers] The error I get: Part::pkspec1: The expression u[1] cannot be used as a part specification. >> Answer Ok, it seems that one can get around Mathematica trying to evaluate vec2[[u[1]]] too early by using the function Indexed[vec2,u[1]] . The working MWE would then look like the following: vars = u@# & /@ Range[3]; cons = Flatten@{ Table[(u[j] != #) & /@ vars[[j + 1 ;; -1]], {j, 1, 3 - 1}], 1 vec1 = {1, 2, 3}; vec2 = {1, 2, 3}; NMinimize[ {Total@((vec1[[#]] - Indexed[vec2, u[#]])^2 & /@ R...
Post a Comment
Read more

What is and isn't a valid variable specification for Manipulate?

I have an expression whose terms have arguments (representing subscripts), like this: myExpr = A[0] + V[1,T] I would like to put it inside a Manipulate to see its value as I move around the parameters. (The goal is eventually to plot it wrt one of the variables inside.) However, Mathematica complains when I set V[1,T] as a manipulated variable: Manipulate[Evaluate[myExpr], {A[0], 0, 1}, {V[1, T], 0, 1}] (*Manipulate::vsform: Manipulate argument {V[1,T],0,1} does not have the correct form for a variable specification. >> *) As a workaround, if I get rid of the symbol T inside the argument, it works fine: Manipulate[ Evaluate[myExpr /. T -> 15], {A[0], 0, 1}, {V[1, 15], 0, 1}] Why this behavior? Can anyone point me to the documentation that says what counts as a valid variable? And is there a way to get Manpiulate to accept an expression with a symbolic argument as a variable? Investigations I've done so far: I tried using variableQ from this answer , but it says V[1...
Post a Comment
Read more