I had high hopes for the Rstudio Cloud but became quite desperate that it doesn't run in cluster mode - which would be a major advantage over using a local machine.

Would be very very happy to receive any *concrete* advice how to solve this. Reducing the number of cores doesn't matter - any number leads to the same error.

.

The following caret::train code runs without problems on my MacBook Pro (MacOs Mojave):

```
system.time(
models.list <- algorithm_list %>%
map(function(algorithm_label) {
train(formula1
, method = algorithm_label
, data = if (is.null(try_first)) training.set else head(training.set, try_first)
, preProcess = c("center", "scale")
, trControl = training_configuration
)
}) %>%
setNames(algorithm_list)
) %>% print
```

The code is run on a cluster initiated by library(doParallel):

```
require(doParallel) # loads parallel library for makeCluster
cluster.new <- makeCluster(spec = if (!is.null(no_cores)) no_cores else { detectCores() - 1 },
type = "FORK",
outfile = "" # verbose
)
registerDoParallel(cluster.new)
```

The error - only in Rstudio Cloud - is:

```
Error in unserialize(socklist[[n]]) : error reading from connection
40.
unserialize(socklist[[n]])
39.
recvOneData.SOCKcluster(cl)
38.
recvOneData(cl)
37.
recvOneResult(cl)
36.
dynamicClusterApply(cl, fun, length(x), argfun)
35.
clusterApplyLB(cl, argsList, evalWrapper)
34.
e$fun(obj, substitute(ex), parent.frame(), e$data)
33.
foreach(iter = seq(along = resampleIndex), .combine = "c", .verbose = FALSE,
.export = export, .packages = "caret") %:% foreach(parm = 1L:nrow(info$loop),
.combine = "c", .verbose = FALSE, .export = export, .packages = "caret") %op%
{ ...
32.
nominalTrainWorkflow(x = x, y = y, wts = weights, info = trainInfo,
method = models, ppOpts = preProcess, ctrl = trControl, lev = classLevels,
...)
31.
train.default(x, y, weights = w, ...)
30.
train(x, y, weights = w, ...)
29.
train.formula(formula1, method = algorithm_label, data = if (is.null(try_first)) training.set else head(training.set,
try_first), preProcess = c("center", "scale"), trControl = training_configuration)
28.
train(formula1, method = algorithm_label, data = if (is.null(try_first)) training.set else head(training.set,
try_first), preProcess = c("center", "scale"), trControl = training_configuration)
27.
.f(.x[[i]], ...)
26.
map(., function(algorithm_label) {
train(formula1, method = algorithm_label, data = if (is.null(try_first))
training.set
else head(training.set, try_first), preProcess = c("center", ...
25.
function_list[[i]](value)
24.
freduce(value, `_function_list`)
23.
`_fseq`(`_lhs`)
22.
eval(quote(`_fseq`(`_lhs`)), env, env)
21.
eval(quote(`_fseq`(`_lhs`)), env, env)
20.
withVisible(eval(quote(`_fseq`(`_lhs`)), env, env))
19.
algorithm_list %>% map(function(algorithm_label) {
train(formula1, method = algorithm_label, data = if (is.null(try_first))
training.set
else head(training.set, try_first), preProcess = c("center", ...
18.
system.time(models.list <- algorithm_list %>% map(function(algorithm_label) {
train(formula1, method = algorithm_label, data = if (is.null(try_first))
training.set
else head(training.set, try_first), preProcess = c("center", ...
17.
eval(lhs, parent, parent)
16.
eval(lhs, parent, parent)
15.
system.time(models.list <- algorithm_list %>% map(function(algorithm_label) {
train(formula1, method = algorithm_label, data = if (is.null(try_first))
training.set
else head(training.set, try_first), preProcess = c("center", ...
14.
.f(target_label = .l[[1L]][[i]], features_set = .l[[2L]][[i]],
...)
13.
pmap(., train_model_permutations, data_set = dataset, algorithm_list = algorithm.list,
training_configuration = trainControl(method = "repeatedcv",
number = 10, repeats = CV.REPEATS), cv_repeats = CV.REPEATS,
try_first = TRY.FIRST)
12.
function_list[[k]](value)
11.
withVisible(function_list[[k]](value))
10.
freduce(value, `_function_list`)
9.
`_fseq`(`_lhs`)
8.
eval(quote(`_fseq`(`_lhs`)), env, env)
7.
eval(quote(`_fseq`(`_lhs`)), env, env)
6.
withVisible(eval(quote(`_fseq`(`_lhs`)), env, env))
5.
model.permutations.list %>% pmap(train_model_permutations, data_set = dataset,
algorithm_list = algorithm.list, training_configuration = trainControl(method = "repeatedcv",
number = 10, repeats = CV.REPEATS), cv_repeats = CV.REPEATS,
try_first = TRY.FIRST)
4.
system.time(result.permutations <- model.permutations.list %>%
pmap(train_model_permutations, data_set = dataset, algorithm_list = algorithm.list,
training_configuration = trainControl(method = "repeatedcv",
number = 10, repeats = CV.REPEATS), cv_repeats = CV.REPEATS, ...
3.
eval(lhs, parent, parent)
2.
eval(lhs, parent, parent)
1.
system.time(result.permutations <- model.permutations.list %>%
pmap(train_model_permutations, data_set = dataset, algorithm_list = algorithm.list,
training_configuration = trainControl(method = "repeatedcv",
number = 10, repeats = CV.REPEATS), cv_repeats = CV.REPEATS, ...
```