Rstan stopped working with multiple cores

Summary:

I was using Rstan with multiple cores on my laptop and it worked just fine. It suddenly stopped working and now continues to be broken. I've restarted the computer, R, re-installed Rstan and its dependencies, but the error persists.

Description:

The code works fine if I set

options(mc.cores = 1)

but breaks for multiple cores, e.g.,

options(mc.cores = 2)
options(mc.cores = parallel::detectCores())

Reproducible Steps:

Please report steps to reproduce the issue. If it's not possible to reproduce, please include a description of how you discovered the issue.

If you have a reproducible example, please include it.

Current Output:

fit_gen_lognormal_shift_constrained <-

• stan(file = 'LogNormalShiftConstrained_ReadingTimes_stationary_gen.stan',

•    data = ReadingTimes_data,
  

•    chains = 4,
  

•    iter = 2000)
  

starting worker pid=841 on localhost:11528 at 14:13:31.618
Error in socketConnection(master, port = port, blocking = TRUE, open = "a+b", :
cannot open the connection
Calls: ... doTryCatch -> recvData -> makeSOCKmaster -> socketConnection
In addition: Warning message:
In socketConnection(master, port = port, blocking = TRUE, open = "a+b", :
localhost:11528 cannot be opened
Execution halted

Expected Output:

If applicable, the output you expected from RStan.

RStan Version:

rstan (Version 2.17.3, GitRev: 2e1f913d3ca3)

R Version:

platform x86_64-apple-darwin15.6.0
arch x86_64
os darwin15.6.0
system x86_64, darwin15.6.0
status
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

Operating System:

Mac OS 10.13.3 (17D47)

Start with the reported stan(...) call using options(mc.cores = 1), 2, and parallel::detectCores(), then compare the socketConnection error and worker startup output. Check the reported RStan 2.17.3, R 3.4.3, and macOS 10.13.3 environment; the issue is done when multi-core execution works while the single-core case remains working.