demo/new_allgather.r

In RBigData/pbdMPI: R Interface to MPI for HPC Clusters (Programming with Big Data Project)

suppressMessages(library(pbdMPI, quietly = TRUE))

x <- 1L:10L

### New method.
pbdMPI:::api.comm.split.by.node()
t1 <- system.time({
  i <- 1
  repeat{
    y1 <- pbdMPI:::api.allgather.integer(x)
    i <- i + 1
    if(i > 1000) break
  }
})
comm.print(length(y1))
comm.print(t1)

### Org method.
t2 <- system.time({
  i <- 1
  repeat{
    y2 <- spmd.allgather.integer(x, integer(length(x) * spmd.comm.size()))
    i <- i + 1
    if(i > 1000) break
  }
})
comm.print(length(y2))
comm.print(t2)

comm.print(sum(y1 == y2))

finalize()