Also using R-devel might help - the forking support in parallel has been made more robust against race conditions, but the changes are probably too substantial to port to 3.4.x. If you find how to cause a race condition using parallel/forking in R-devel, a report would be greatly appreciated.


On 02/11/2018 09:51 PM, T. Florian Jaeger wrote:
Dear Henrik,

thank you, for the quick reply. Bizarrely enough, the problem vanished when
I woke the computer from sleep (I had previously replicated the problem
after several restarts of both R and the MacOS).

I will follow-up if I can again replicate the problem.


On 2/10/18 4:39 PM, Henrik Bengtsson wrote:
A few quick comments:

* You mention R --vanilla, but make sure to try with
parallel::makeCluster(), so that you don't happen to pick up
snow::makeCluster() if 'snow' is attached and ahead of parallel on the
search() path.

* Try creating a single background worker, i.e. parallel::makeCluster(1L).

* Try with cl <- future::makeClusterPSOCK(1L, verbose = TRUE), which
gives the same thing, but it also show you some details on what it
does internally; that may give some clues where it stalls.


On Sat, Feb 10, 2018 at 12:11 PM, T. Florian Jaeger
<> wrote:
Hi all,

I can't get the functionality of the package parallel to work. Specifically,
makeCluster() hangs when I run it. I first noticed the problem when trying
to run Rstan with multiple cores and the traced it back to the core package
parallel. The following results in R hanging after the call to makeCluster.


# Calculate the number of cores
no_cores <- detectCores() - 1

# Initiate cluster
cl <- makeCluster(no_cores)

I'm running MacOS High Sierra 10.13.3 (17D47) on a MacbookPro 2017 laptop
with 4 cores.

platform       x86_64-apple-darwin15.6.0
arch           x86_64
os             darwin15.6.0
system         x86_64, darwin15.6.0
major          3
minor          4.3
year           2017
month          11
day            30
svn rev        73796
language       R
version.string R version 3.4.3 (2017-11-30)
nickname       Kite-Eating Tree

The problem replicates in R --vanilla

I've spent hours googling for solutions but can't find any reports of this
problem. Any help would be appreciated.


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