how to parallelize the sending of data to the database

Question

I have a large csv file. I read the file every 10000 lines then send these lines to a database, it takes a lot of time. What I would like to test is to parallelize. I implemented this code but nothing happens, there are no errors.

library(parallel); library(doParallel); library(RMySQL);  

con <- dbConnect(MySQL(), host = host, user = user, password = password, dbname = database)

path <- "file.csv"
col_names <- colnames(read.csv(path, header = T, nrows = 1))
offsets <- seq(0, file.info(path)$size / 2, by = batch_size) # length(offsets) = 335363
batch_size <- 10000

cl <- makeCluster(detectCores())
registerDoParallel(cl)
foreach(i = 1:length(offsets), .packages = c("DBI")) %dopar% {
  header <- if(i > 1) F else T
  setb <- read.csv(path, skip = offsets[i], nrows = batch_size, 
                   header = header)
  colnames(setb) <- col_names
  dbWriteTable(con, "table1", setb, append = TRUE)
}

stopCluster(cl); dbDisconnect(con)