如何正确实现R语言中的定时等待以规避每小时下载限制

I once saw an R example for a 10-second code wait:

period <- 10 ## minimum time (in seconds) that the loop should run for
tm <- Sys.time() ## starting date & time
while (difftime(Sys.time(), tm, units = "secs")[[1]] < period)

Now I need to pause my program for one hour because of hourly download limits. I tried writing this code:

period <- 60
tm <- Sys.time() ## starting date & time
while (difftime(Sys.time(), tm, units = "minutes")[[1]] < period)

But I don't think this approach is correct. Can anyone help me find a proper implementation method?

Hey there, let's sort this out for you!

First off, your current loop approach isn't ideal—it's what's called a "busy wait," meaning it's constantly checking the time and eating up unnecessary CPU resources. R actually has a built-in function made exactly for pausing execution cleanly: Sys.sleep().

The Simple, Efficient Solution #

If all you need is to pause the program for one hour, just use this one line:

# Pause for 1 full hour (3600 seconds total)
Sys.sleep(3600)

Sys.sleep() takes a number of seconds as its argument, so we calculate 60 minutes × 60 seconds = 3600. This puts your program to sleep without wasting any processing power while waiting.

Why Your Original Approach Falls Short #

Right now, your while loop doesn't have any code inside it—without a body (like a NULL or small sleep), it could even run infinitely. Even if you added something, the loop would still be spinning non-stop checking the time, which is totally unnecessary when Sys.sleep() handles this task perfectly.

If You Must Use a Time-Check Loop (Not Recommended) #

If you have a specific reason to use a time-based loop (like needing to run small tasks while waiting), at least add a short sleep inside the loop to cut down on CPU usage:

period <- 3600  # 1 hour in seconds
tm <- Sys.time()
while (difftime(Sys.time(), tm, units = "secs")[[1]] < period) {
  Sys.sleep(1)  # Wait 1 second between time checks to save CPU
}

But again, the Sys.sleep(3600) method is the standard best practice here.

内容的提问来源于stack exchange，提问作者Tom