---
title: "Parallel Execution for Confidence Intervals"
author: "Justin Kamerman"
date: "`r Sys.Date()`"
output: rmarkdown::html_vignette
vignette: >
  %\VignetteIndexEntry{Parallel Execution for Confidence Intervals}
  %\VignetteEngine{knitr::rmarkdown}
  %\VignetteEncoding{UTF-8}
---
To leverage multicore processors to speed up calcualtion of confidence intervals, use the `parallel` package to create a cluster and attach the `qfasa.parallel.cluster ` option.

The cluster can be used for multiple invocations of `beta.meths.CI()` but should be shut down when work is complete to free up resources.



## Set Number of Cores
For maximum speedup, set the `qfasa.parallel.numcores` option to the total number of cores on your computer. The number of cores can be determined using the `detectCores()` function.

```{r, eval=TRUE}
parallel::detectCores()
```

## Create Cluster
```{r, eval=FALSE}
options(qfasa.parallel.numcores = 8)
options(qfasa.parallel.cluster = parallel::makeCluster(getOption('qfasa.parallel.numcores'),
                                                       type='FORK'))
#
# Note that if using windows, do not include type='FORK'.

```

## Confidence Intervals
No change is required to the `conf.meth()` call. The implementation will automatically detect the cluster and use it to parallelize the bootstrap iterations.

## Shut Down Cluster
```{r, eval=FALSE}
parallel::stopCluster(getOption('qfasa.parallel.cluster'))
```

## Portability
Parallel execution has been tested on Ubuntu Linux, AWS Linux, and MacOS platforms only.