Using rslurm to clip rasters

Question

I have several thousand small glacier rasters (in rectangular shape) that need to be clipped to the glacier's extent. I have the glacier polygons stored in a large SpatialPolygonsDataFrame (matching in length and position).

I need parallel computing or else it would take forever, so I would like to use the rslurm package.

My code so far (using the for-loop provided here: https://gis.stackexchange.com/a/342955/145570)

library(rslurm)

fun_clip_rslurm <- function(filelocations, filenames, glaciers){
  for(i in 1:length(filelocations)){
    r = raster(filelocations[i]) # get the ith file name
    g = glaciers[i,] # get the i'th row of `glaciers`.
    r = crop(r, g) # crop
    writeRaster(r, file.path("/data/.../RGI60-13_crop/", filenames[i]))
  }
}

params <- list(filelocations, filenames, glaciers)
names(params) <- c("filelocations", "filenames", "glaciers")

slurm_call(fun_clip_rslurm, params, jobname = "my_crop",
           slurm_options = list(time="1-00:00:00", share =TRUE), 
           submit = TRUE)

If I run this, I get the following error message:

sbatch: error: Batch job submission failed: Invalid account or account/partition combination specified
$jobname
[1] "my_crop"

$nodes
[1] 1

attr(,"class")
[1] "slurm_job"

So now I have two questions:
Do I have to give rslurm some kind of permission to run the batch-script on the cluster?
And how can I specify the number of nodes on which to run the calculation?

Answer 1

Okay, I found out what the problem was.

First: slurm_callwas not the right function, slurm_applywas more to the point, because I needed more than just one function call. With slurm_applyI can easily specify the number of nodes and cpus per node.
Secondly, I was having some permission problems that had nothing do to with my code and IT fixed it.
Now my code looks the following and runs like a charm:

fun_clip_rslurm <- function(filelocation, filename, glacier_index){
    r = raster(filelocation) 
    r = projectRaster(r, crs=my_CRS) # global object
    g = glaciers[glacier_index,] 
    r = crop(r, g)
    writeRaster(r, file.path("/data/.../", filename), overwrite = TRUE)
}

params <- data.frame(filelocation = filelocations, filename = filenames, glacier_index = 1:length(filenames),
                     stringsAsFactors = FALSE)

results <-  slurm_apply(fun_clip_rslurm, params, jobname = "DEM_crop",
            add_objects = c("glaciers", "my_CRS"), # feed in the global objects
            cpus_per_node = 20, nodes = 2000,
            slurm_options = list(time="0-01:00:00"), 
            submit = TRUE)

cleanup_files(results, wait = TRUE)