[saurik]

It seems that there was good reason to challenge your numbers: you are using "concurrent users hitting my site" in a way that people in a website optimization context would not ever expect. This screenshot is talking about "concurrent visits", and has a figure for the average time that users were "engaged" (over 45 minutes). These are not performance measurements: they are the kinds of metrics you use to determine how interesting and sticky the content of your site is (along with things like your bounce rate and content flow).

In fact, this number (apparently a feature of Chartbeat) claims to be measuring "concurrent people sitting at a computer looking at pages from your site", not concurrent requests or "hits" to your webserver, or even concurrent HTTP connections (which may be idle for long periods of time). This number is almost entirely meaningless for the purposes of discussing your site's load. Imagine an HTML5 JavaScript game that took an entire day to play: with one request per second you may find yourself with tens of thousands of "concurrent visits".

[tahoecoder]

Knowing how many people are on your pages at any one time isn't a meaningless number. You're right in the sense that it's not a great way to assess quantitative site load. I just used that number in the blog to give a qualitative assessment of how many people were currently on my site.

Also, you are misunderstanding this chartbeat number. These 282 visitors weren't spread out over 45 minutes. These are real time users. Granted, some users are idle but most are interacting with the pages.

If this blog post were about the specifics of server load from a #1 HN post, I wouldn't even use the chartbeat figure. The post was about middleman + s3 + cloudfront. The chartbeat figure was more than enough to give readers a qualitative glance of how many people were looking at my site.

[saurik]

You had ~2250 visits that day (1440 minutes), each of which spent (on average) ~45 minutes looking at your website. Assuming only one concurrent visitor, you'd have had 1440/45 = 32 total visits. You actually had 2250/32 = ~70 times that number, so you averaged ~70 concurrent visits that day.

Due to expected fluctuations (day/night, when you posted to HN) there will be considerable real-time variation; it is easy to believe that you spiked up to 282 concurrent visitors at some point when people were heavily commenting on HN: however, the real question here is what the concurrent number of requests looked like.

Finally, yes: one way to look at these visitors is that they were "spread out over 45 minutes" (although that isn't how I'd describe it myself). If you asked "during any given 45 minute period, how many visits (on average) started during that period", we would be looking at 2250/(1440/45), or ~70 visits starting in that window.

[tahoecoder]

Creating a daily average of concurrent visits isn't relevant. Servers don't take an average of all the possible future hours of complete inactivity when they are serving up requests.

The post was only up at the top for a couple of hours before the server performance got so bad such that everyone started flagging it. My post then dropped off the front page and quickly went to page 4 or 5 due to the flagging.

I agree with you that the more interesting number would be the the concurrent number of requests.

[saurik]

> Servers don't take an average of all the possible future hours of complete inactivity when they are serving up requests.

I did that math to demonstrate that you are misunderstanding the relevancy of the Chartbeat number: that yes, if you look at the values "over 45 minutes" that is slightly weird, but entirely accurate, as it is not in any way unlikely that you had a spike four times your average during the day (that's why I had to calculate the average: to see if your maximum value was unexpected; I did the calculation of the average using the way of interpreting the chart which you believe is flawed, and it turns out that it is entirely consistent).

> The post was only up at the top for a couple of hours before the server performance got so bad such that everyone started flagging it.

Sure: your site was slow (I'm not questioning that your site was slow: tons of websites hit HN and then fall apart, it seems to be a daily occurrence), but I still don't know how you accomplished it with this small a number of users.