R CRAN code. Parallel execution - helper functions for the "multicore" library. Run jobs (expressions) in the background without blocking. Consider using "source.gist" http://cran.r-project.org/web/packages/source.gist/index.html

background.multicore.r

################
################ Parallel execution - helper functions for multicore library
################ Run jobs (expressions) in the background without blocking
################ 

library(multicore) #better to be loaded last of all libraries 

inpar<-function(name,expr){
#Runs named expression in parallel with main thread - non-blocking
 name<-deparse(substitute(name)) 
 vname<-paste(name,"tocollect",sep=".")
 print(paste(vname,Sys.time()))
 assign(vname, list(mcparallel(eval(expr),name)), envir=.GlobalEnv)
}


cpar<-function(name){
#Collects previously run expression if finished - non-blocking
 name<-deparse(substitute(name)) 
 vname<-paste(name,"tocollect",sep=".")
 vjob<-get(vname,envir=.GlobalEnv)[[1]]
 cres<-collect(vjob,wait=FALSE,timeout=1)
 print(paste("Obtained result:",!is.null(cres)))
 if (!is.null(cres)){
    while (!is.null(readChild(vjob$pid))){}
    assign(name,cres[[1]], envir=.GlobalEnv) 
 }
 print("Children left:")
 print(children()) 
}

kill.all.jobs<-function(){
    print(children())
    while(!is.null(readChildren())) TRUE;
    print("Children left:")
    print(children())
}

ex<-expression

##Example use
#inpar(testp, ex( mean(rnorm(1000)) ) )
#cpar(testp)
#testp
#inpar(testp2,ex({Sys.sleep(10); 1}))
#cpar(testp2)
#testp2
##Wait for background task completion...
#Sys.sleep(10)
#cpar(testp2)
#testp2