Hi,
I really try to understand why working with parallel package, code seems to
be slower using inside a function... for example :
# data
don <- lapply(1:150, function(x){data.frame(a = rnorm(100000), b =
rnorm(100000))})
# inline test
t0 <- Sys.time()
require(parallel)
cl <- makeCluster(4)
res <- parLapplyLB(cl, don, function(x){1})
stopCluster(cl)
Sys.time()-t0 # 3.5 sec, each thread up to 90 Mo
# using function
parF <- function(data){
require(parallel)
cl <- makeCluster(4)
result <- parLapply(cl, data, function(x){1})
stopCluster(cl)
}
system.time(res2 <- parF(don)) # 9.5 sec, each thread up to 320 Mo ...!
It's seems that, using inside a function :
- is 3x slower...
- more data is loaded into each thread...!
Thanks.
--
Benoit Thieurmel +33 6 69 04 06 11 10 place de la Madeleine - 75008 Paris
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