inst/examples/Sorts.R

In matloff/Rdsm: Parallel Threads Environment for R

# threads configuration: run
# rthreadsSetup(nThreads=2,
#    sharedVars=list(nextRowNum=c(1,1,3),m=c(10,100000000)))

setup <- function()  # run in "manager thread"
{
   # generate vectors to be sorted, of different sizes
   tmp <- c(30000000,70000000)
   set.seed(9999)
   nvals <- sample(tmp,10,replace=TRUE)  # 10 vectors to sort
   for (i in 1:10) {
      n <- nvals[i]
      m[i,1:(n+1)] <- c(n,runif(n))
   }
}

doSorts <- function()  # run in all threads, maybe with system.time()
{

   rowNum <- myGlobals$myID+1  # my first vector to sort

   while (rowNum <= nrow(m)) {
      # as illustration of parallel operation, see which threads execute
      # sorts on which rows
      print(rowNum)
      n <- m[rowNum,1]
      x <- m[rowNum,2:(n+1)]
      m[rowNum,2:(n+1)] <- sort(x)
      rowNum <- rthreadsAtomicInc('nextRowNum')
   }

   # rthreadsWaitDone()
   rthreadsBarrier()

}