4 ms·

Falsehoods programmers believe: - Sleep(1) sleeps for exactly 1 second. - Sleep(1) sleeps for approximately 1 second. - Sleep(1) sleeps for at least 1 second

by haiku2077 2y ago

Falsehoods programmers believe: - Sleep(1) sleeps for exactly 1 second. - Sleep(1) sleeps for approximately 1 second. - Sleep(1) sleeps for at least 1 second. - Sleep(1) sleeps for an unknown, but short amount of time. Certainly not weeks, months or years.

deleted 2y ago
[deleted]
teddyh 2y ago
More Falsehoods programmers believe about time: <https://gist.github.com/timvisee/fcda9bbdff88d45cc9061606b4b923ca https://gist.github.com/timvisee/fcda9bbdff88d45cc9061606b4b...>
Dylan16807 2y ago
"Approximately 1 second" is fine. You just have to keep in mind that other influences can block your program from running. Those other influences can trigger even if you don't sleep!
a1369209993 2y ago
> Sleep(1) sleeps for approximately 1 second. This is correct - Sleep(1) does sleep for approximately 1 second; the problem is you're confusing the 95% confidence interval (which might be as narrow as (999ms,1001ms) for some reasonable designs) with the absolute error bounds (which are (0ms,∞ms], and yes, the infinity end is inclusive).
- haiku2077 2y ago
  If your software is running on a VM, and that VM is suspended (e.g. for migration), the end of sleep could be minutes or months in future. This is surprisingly common when running on certain VM instance types on public cloud! Common enough that I've had to account for it in production code.
  - trifurcate 2y ago
    The confidence interval comment still applies for any production or client environment I've ever deployed code to. Unless you actually expect your environment to spend more than 5% of its time on average getting suspended and resumed. Maybe you work on some tooling that is scheduled to run right around migration time (for servers) or sleep/resume time (for clients).
    - haiku2077 2y ago
      Or you run at scale on a public cloud provider. We observe a few of these events per month.
NemoNobody 2y ago
Haha, this is one of the best comments I've read on HN

deleted 2y ago

[deleted]

teddyh 2y ago

More Falsehoods programmers believe about time: <https://gist.github.com/timvisee/fcda9bbdff88d45cc9061606b4b923ca https://gist.github.com/timvisee/fcda9bbdff88d45cc9061606b4b...>

Dylan16807 2y ago

"Approximately 1 second" is fine. You just have to keep in mind that other influences can block your program from running. Those other influences can trigger even if you don't sleep!

a1369209993 2y ago

> Sleep(1) sleeps for approximately 1 second. This is correct - Sleep(1) does sleep for approximately 1 second; the problem is you're confusing the 95% confidence interval (which might be as narrow as (999ms,1001ms) for some reasonable designs) with the absolute error bounds (which are (0ms,∞ms], and yes, the infinity end is inclusive).

haiku2077 2y ago
If your software is running on a VM, and that VM is suspended (e.g. for migration), the end of sleep could be minutes or months in future. This is surprisingly common when running on certain VM instance types on public cloud! Common enough that I've had to account for it in production code.
- trifurcate 2y ago
  The confidence interval comment still applies for any production or client environment I've ever deployed code to. Unless you actually expect your environment to spend more than 5% of its time on average getting suspended and resumed. Maybe you work on some tooling that is scheduled to run right around migration time (for servers) or sleep/resume time (for clients).
  - haiku2077 2y ago
    Or you run at scale on a public cloud provider. We observe a few of these events per month.

NemoNobody 2y ago

Haha, this is one of the best comments I've read on HN