In RStudio with R4.0.0, parallel::makePSOCKcluster("localhost") fails/hangs

ssp3nc3r · April 24, 2020, 8:44pm

my <- parallel::makePSOCKcluster("localhost") fails/hangs in RStudio but not in terminal/command-line R.

System Information:

RStudio Edition: (Desktop)
RStudio Version: 1.3.947
OS Version: Mac OSX Catalina
R Version: 4.0.0

sessionInfo()
R version 4.0.0 (2020-04-24)
Platform: x86_64-apple-darwin17.0 (64-bit)
Running under: macOS Catalina 10.15.4

Matrix products: default
BLAS: /System/Library/Frameworks/Accelerate.framework/Versions/A/Frameworks/vecLib.framework/Versions/A/libBLAS.dylib
LAPACK: /Library/Frameworks/R.framework/Versions/4.0/Resources/lib/libRlapack.dylib

locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

attached base packages:
[1] stats graphics grDevices utils datasets methods base

loaded via a namespace (and not attached):
[1] compiler_4.0.0 tools_4.0.0

Referred here from support.rstudio.com

ssp3nc3r · April 24, 2020, 9:53pm

Appears to be related to:

github.com/rstudio/rstudio

parallel::makeCluster() freezes RStudio on macOS with R 4.x

opened 01:20PM - 19 Apr 20 UTC

closed 06:31PM - 18 Mar 21 UTC

RLumSK

bug

### System details RStudio Edition : Desktop RStudio Version : 1.3.9…44 OS Version : macOS Catalina 10.15.4 R Version : R-devel (2020-04-18 r78249) ### Steps to reproduce the problem ```r cl <- parallel::makeCluster(1) ``` Same if the number of nodes is > 1. ### Describe the problem in detail I have got a (so far) unpublished R package using MC simulations that suddenly did not work anymore. Every time when I tried to start the simulation RStudio went to 100 % CPU load and did nothing anymore. Sometimes, in particular, during the first seconds, I could press the 'stop' button to shutdown the R process. If I waited too long, I had to kill the RStudio process. I narrowed down the problem to the single code line shown above. However, plain R (in the terminal or the R GUI) does work without any problem. I did run the following combinations: R version | R Studio (1.3.938) | R Studio (1.3.944) | R Studio (1.2.5042) ----------|-----------------|--------------------| -------------------| R-devel | FREEZE | FREEZE | FREEZE | FREEZE | R 4.0 RC | NA | FREEZE | FREEZE | R 3.6.3 | NA | OK | NA NA: not tested. My best guess is that this issue is related to [recent changes](https://developer.r-project.org/Blog/public/2020/03/17/socket-connections-update/) in 'parallel' Important (and again), it works in the R terminal and the normal R GUI, so, therefore, I believe that something needs to be modified in RStudio (I might be wrong though). Side note: If I used the RStudio check and build functionality where I also test examples, RStudio works fine. #### Update 2020-04-24 I realised that `FREEZE` is probably not correct, the default timeout for the connection between master and worker in `parallel::makeCluster()` is two minutes. If you wait the full time, R will throw the following error message : ``` > cl <- parallel::makeCluster(2) Error in makePSOCKcluster(names = spec, ...) : Cluster setup failed. 2 of 2 workers failed to connect. ``` ### Describe the behaviour you expected Calling ```r cl <- parallel::makeCluster(1) ``` does not freeze RStudio or fails with the mentioned error message. ### Update 2020-04-26, potential intermediate work-around Since I had to continue testing with R 4.X and I wanted to use *RStudio**, I played a little bit with the parameters, and (at least on my machine), I figured out the following: If I use the parameter `setup_timeout` and set it to < 1 s, it still works. Example: ```r cl <- parallel::makeCluster(10, setup_timeout = 0.5) ``` I tested up to 100 nodes, without any problem. Obviously this **is not** a fix, and it may be different on other machines (not to mention that one may want to have these longer timeouts). However, it may provide an intermediate solution until a fix can be provided. Values > 1 s consistently did not work for me, according to the manual entry for `parallel::makeCluster` the default is 2 min.  - [X] I have read the guide to submitting good bug reports at https://github.com/rstudio/rstudio/wiki/Writing-Good-Bug-Reports . - [X] I have installed the latest version of RStudio and confirmed that the issue still persists. - [ ] If I am reporting a RStudio crash, I have included a diagnostics report. https://support.rstudio.com/hc/en-us/articles/200321257-Running-a-Diagnostics-Report *Not applicable, it does not really crash.* - [X] I have done my best to include a minimal, self-contained set of instructions for consistently reproducing the issue.

system · May 15, 2020, 9:53pm

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