53-error-handling.md

Error Handling

The errorhandling option specifies how failed tasks should be evaluated. By default, the error handling is 'stop' to ensure users' can have reproducible results. If a combine function is assigned, it must be able to handle error objects.

Error Handling Type	Description
stop	The execution of the foreach will stop if an error occurs
pass	The error object of the task is included the results
remove	The result of a failed task will not be returned

# Remove R error objects from the results
res <- foreach::foreach(i = 1:4, .errorhandling = "remove") %dopar% {
  if (i == 2 || i == 4) {
    randomObject
  }
  
  mean(1:3)
}

#> res
#[[1]]
#[1] 2
#
#[[2]]
#[1] 2

# Passing R error objects into the results 
res <- foreach::foreach(i = 1:4, .errorhandling = "pass") %dopar% {
  if (i == 2|| i == 4) {
    randomObject
  }
  
  sum(i, 1)
}

#> res
#[[1]]
#[1] 2
#
#[[2]]
#<simpleError in eval(expr, envir, enclos): object 'randomObject' not found>
#
#[[3]]
#[1] 4
#
#[[4]]
#<simpleError in eval(expr, envir, enclos): object 'randomObject' not found>