问题描述
我有一台运行 R 4.0.2 的 8 核 RHEL Linux 机器.
I have an 8-core RHEL Linux machine running R 4.0.2.
如果我向 R 询问内核数量，我可以确认有 8 个可用.
If I ask R for the number of cores, I can confirm that 8 are available.
> print(future::availableWorkers())
[1] "localhost" "localhost" "localhost" "localhost" "localhost" "localhost"
[7] "localhost" "localhost"
> print(parallel::detectCores())
[1] 8
但是，如果我运行这个简单的例子
However, if I run this simple example
f <- function(out=0) {
for (i in 1:1e10) out <- out + 1
}
output <- parallel::mclapply(1:8, f, mc.cores = 8)
my top 表示只使用了 1 个内核(因此每个 worker 使用该内核的 1/8，或整个机器的 1/64).
my top indicates that only 1 core is being used (so that each worker is using 1/8th of that core, or 1/64th of the entire machine).
%Cpu0 :100.0 us, 0.0 sy, 0.0 ni, 0.0 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
%Cpu1 : 0.0 us, 0.0 sy, 0.0 ni,100.0 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
%Cpu2 : 0.0 us, 0.0 sy, 0.0 ni,100.0 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
%Cpu3 : 2.0 us, 0.0 sy, 0.0 ni, 98.0 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
%Cpu4 : 0.0 us, 0.0 sy, 0.0 ni,100.0 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
%Cpu5 : 0.0 us, 0.0 sy, 0.0 ni,100.0 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
%Cpu6 : 0.0 us, 0.0 sy, 0.0 ni,100.0 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
%Cpu7 : 0.0 us, 0.0 sy, 0.0 ni,100.0 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
KiB Mem : 32684632 total, 28211076 free, 2409992 used, 2063564 buff/cache
KiB Swap: 16449532 total, 11475052 free, 4974480 used. 29213180 avail Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
3483 user 20 0 493716 57980 948 R 1.8 0.2 0:18.09 R
3479 user 20 0 493716 57980 948 R 1.5 0.2 0:18.09 R
3480 user 20 0 493716 57980 948 R 1.5 0.2 0:18.08 R
3481 user 20 0 493716 57980 948 R 1.5 0.2 0:18.09 R
3482 user 20 0 493716 57980 948 R 1.5 0.2 0:18.09 R
3484 user 20 0 493716 57980 948 R 1.5 0.2 0:18.09 R
3485 user 20 0 493716 57980 948 R 1.5 0.2 0:18.09 R
3486 user 20 0 493716 57980 948 R 1.5 0.2 0:18.09 R
有人知道这里会发生什么吗?另一个记录类似行为的 StackOverflow 问题是 这里.很明显，我以某种方式搞砸了安装.我按照 RHEL 7 的 这些安装说明进行操作.我猜有依赖性失踪，但我不知道在哪里看.如果有人对运行诊断等有任何想法，他们将不胜感激.
Does anyone know what might be going on here? Another StackOverflow question that documents similar behavior is here. It's clear that I messed up the install somehow. I followed these install instructions for RHEL 7. I'm guessing there is a dependency missing, but I have no idea where to look. If anyone has any ideas of diagnostics to run, etc., they would be most appreciated.
为了进一步了解，我的机器上还安装了 R 3.4.1，当我运行此代码时，一切正常.(我通过 yum 安装了那个版本.)
For further context, I have R 3.4.1 also installed on my machine, and when I run this code, everything works fine. (I installed that version through yum.)
我昨天还使用上面链接的相同说明安装了 R 4.0.3，但它遇到了同样的问题.
I also installed R 4.0.3 yesterday using the same instructions linked above, and it suffers from the same problem.
推荐答案
首次运行
system(sprintf("taskset -p 0xffffffff %d", Sys.getpid()))
那么你的简单例子
f <- function(out=0) { for (i in 1:1e10) out <- out + 1 }
output <- parallel::mclapply(1:8, f, mc.cores = 8)
适用于所有 8 个内核.
works on all 8 cores.
这篇关于R 只在 Linux 中的某个 CPU 上运行的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！