parallel.Rmd

---
title: "Testing parallel"
output:
  html_document: 
    number_sections: yes
---

```{r loadLibs}
library(parallel)
```

See https://www.r-bloggers.com/how-to-go-parallel-in-r-basics-tips/

Set up cluster:
```{r parSetUp} 
# Calculate the number of cores
n_cores <- detectCores() - 1
 
# Initiate cluster
cl <- makeCluster(n_cores, type="FORK") # so all vars & envs go to and it also saves memomry space
```

Using `r n_cores` of the available `r detectCores()` cores.

Do something:

```{r runPar}
myList <- list(1:20)
parLapply(cl, myList,
          tryCatch({
            function(exponent)
              2^exponent
          }, error = function(e) return(paste0("The variable '",
                                               exponent, "'", 
                                               " caused the error: '", 
                                               e, "'"))
          )
)
```

Close the cluster:

```{r closeClus}
stopCluster(cl)
```