setsnapshotDate is slow when MRAN servers are down

[ethanbsmith]

I am assuming that the online parameter is intended to work similarly to the way ScanForPackages does in the checkpoint function

this may be similar to #234

>system.time(setSnapshot(snapshotDate = "2018-05-30", online = F))
Using CRAN mirror at http://mran.microsoft.com/snapshot/2018-05-30
   user  system elapsed 
   0.00    0.00   21.25

Not your problem, but for reference, spinning up a cluster is now taking minutes with this in the code path

> system.time(makeCluster(detectCores(logical = FALSE)))
   user  system elapsed 
   0.02    0.00   87.44 

Faster than with online = T , but still very slow.

system.time(setSnapshot(snapshotDate = "2018-05-30", online = T))
Error in setSnapshot(snapshotDate = "2018-05-30", online = T) : 
  Invalid snapshot date.
Timing stopped at: 0 0 42.42

> sessionInfo()
R version 3.4.3 (2017-11-30)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 17134)

Matrix products: default

locale:
[1] LC_COLLATE=English_United States.1252  LC_CTYPE=English_United States.1252    LC_MONETARY=English_United States.1252 LC_NUMERIC=C                          
[5] LC_TIME=English_United States.1252    

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

other attached packages:
[1] RevoUtilsMath_10.0.1 RevoUtils_10.0.7     RevoMods_11.0.0      MicrosoftML_9.3.0    mrsdeploy_1.1.3      RevoScaleR_9.3.0     lattice_0.20-35      rpart_4.1-11         checkpoint_0.4.3    

loaded via a namespace (and not attached):
 [1] codetools_0.2-15       CompatibilityAPI_1.1.0 foreach_1.4.5          grid_3.4.3             R6_2.2.2               jsonlite_1.5           curl_3.1               iterators_1.0.9       
 [9] tools_3.4.3            compiler_3.4.3         rtvs_1.0.0.0           mrupdate_1.0.1        
> 

[sfweller]

Thanks for the report! I have been unable to repro the problem so far, but I am still working on a reproduce.

[ethanbsmith]

Timing now that MRAN servers are back up:

> system.time(setSnapshot(snapshotDate = "2018-05-30", online = T))
Using CRAN mirror at https://mran.microsoft.com/snapshot/2018-05-30
   user  system elapsed 
   0.19    0.01    0.96 

> system.time(setSnapshot(snapshotDate = "2018-05-30", online = F))
Using CRAN mirror at https://mran.microsoft.com/snapshot/2018-05-30
   user  system elapsed 
   0.15    0.01    0.64 

So were dealing with a difference of > 20 seconds if the MRAN servers are down and online = F

Also, from memory, #234 has some discussion about how to simulate network unavailability for testing

[vspinu]

For me checkpoint::checkpoint takes 30 sec and 16 secs with scanForPackages = FALSE. This interferes with my restart-R-as-needed workflow quite a bit.

[hongooi73]

In v1.0, checkpoint no longer queries the snapshot list as part of everyday functioning.