Skip to content
By using Twitter’s services you agree to our Cookies Use. We and our partners operate globally and use cookies, including for analytics, personalisation, and ads.

This is the legacy version of twitter.com. We will be shutting it down on June 1, 2020. Please switch to a supported browser, or disable the extension which masks your browser. You can see a list of supported browsers in our Help Center.

  • Home Home Home, current page.
  • About

Saved searches

  • Remove
  • In this conversation
    Verified accountProtected Tweets @
Suggested users
  • Verified accountProtected Tweets @
  • Verified accountProtected Tweets @
  • Language: English
    • Bahasa Indonesia
    • Bahasa Melayu
    • Català
    • Čeština
    • Dansk
    • Deutsch
    • English UK
    • Español
    • Filipino
    • Français
    • Hrvatski
    • Italiano
    • Magyar
    • Nederlands
    • Norsk
    • Polski
    • Português
    • Română
    • Slovenčina
    • Suomi
    • Svenska
    • Tiếng Việt
    • Türkçe
    • Ελληνικά
    • Български език
    • Русский
    • Српски
    • Українська мова
    • עִבְרִית
    • العربية
    • فارسی
    • मराठी
    • हिन्दी
    • বাংলা
    • ગુજરાતી
    • தமிழ்
    • ಕನ್ನಡ
    • ภาษาไทย
    • 한국어
    • 日本語
    • 简体中文
    • 繁體中文
  • Have an account? Log in
    Have an account?
    · Forgot password?

    New to Twitter?
    Sign up
colmmacc's profile
Colm MacCárthaigh
Colm MacCárthaigh
Colm MacCárthaigh
@colmmacc

Tweets

Colm MacCárthaigh

@colmmacc

AWS, Apache, Crypto, Irish Music, Haiku, Photography

Seattle
notesfromthesound.com
Joined April 2008

Tweets

  • © 2020 Twitter
  • About
  • Help Center
  • Terms
  • Privacy policy
  • Imprint
  • Cookies
  • Ads info
Dismiss
Previous
Next

Go to a person's profile

Saved searches

  • Remove
  • In this conversation
    Verified accountProtected Tweets @
Suggested users
  • Verified accountProtected Tweets @
  • Verified accountProtected Tweets @

Promote this Tweet

Block

  • Tweet with a location

    You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more

    Your lists

    Create a new list


    Under 100 characters, optional

    Privacy

    Copy link to Tweet

    Embed this Tweet

    Embed this Video

    Add this Tweet to your website by copying the code below. Learn more

    Add this video to your website by copying the code below. Learn more

    Hmm, there was a problem reaching the server.

    By embedding Twitter content in your website or app, you are agreeing to the Twitter Developer Agreement and Developer Policy.

    Preview

    Why you're seeing this ad

    Log in to Twitter

    · Forgot password?
    Don't have an account? Sign up »

    Sign up for Twitter

    Not on Twitter? Sign up, tune into the things you care about, and get updates as they happen.

    Sign up
    Have an account? Log in »

    Two-way (sending and receiving) short codes:

    Country Code For customers of
    United States 40404 (any)
    Canada 21212 (any)
    United Kingdom 86444 Vodafone, Orange, 3, O2
    Brazil 40404 Nextel, TIM
    Haiti 40404 Digicel, Voila
    Ireland 51210 Vodafone, O2
    India 53000 Bharti Airtel, Videocon, Reliance
    Indonesia 89887 AXIS, 3, Telkomsel, Indosat, XL Axiata
    Italy 4880804 Wind
    3424486444 Vodafone
    » See SMS short codes for other countries

    Confirmation

     

    Welcome home!

    This timeline is where you’ll spend most of your time, getting instant updates about what matters to you.

    Tweets not working for you?

    Hover over the profile pic and click the Following button to unfollow any account.

    Say a lot with a little

    When you see a Tweet you love, tap the heart — it lets the person who wrote it know you shared the love.

    Spread the word

    The fastest way to share someone else’s Tweet with your followers is with a Retweet. Tap the icon to send it instantly.

    Join the conversation

    Add your thoughts about any Tweet with a Reply. Find a topic you’re passionate about, and jump right in.

    Learn the latest

    Get instant insight into what people are talking about now.

    Get more of what you love

    Follow more accounts to get instant updates about topics you care about.

    Find what's happening

    See the latest conversations about any topic instantly.

    Never miss a Moment

    Catch up instantly on the best stories happening as they unfold.

    1. Andrew Certain‏ @tacertain 25 May 2019
      • Report Tweet
      • Report NetzDG Violation

      And we knew that we couldn't start off with an edict that no page could *ever* be served with more than 6s of latency. Instead, we thought about probabilities that a customer would have a bad session, which led us to set our SLAs at percentiles.

      1 reply 4 retweets 76 likes
      Show this thread
    2. Andrew Certain‏ @tacertain 25 May 2019
      • Report Tweet
      • Report NetzDG Violation

      If a session was 10 pages on average and we set our SLA to say that no more than 1 in 10,000 pages would have a bad latency, then we would know that no more than 1/1000 customers would have a bad session. In shorthand, the p99.99 of latency needed to be <6s.

      1 reply 10 retweets 121 likes
      Show this thread
    3. Andrew Certain‏ @tacertain 25 May 2019
      • Report Tweet
      • Report NetzDG Violation

      Armed with these graphs and this reasoning, I went to the VPs who owned the various web pages and argued that they needed to set these SLAs. In parallel, we (the perf engr) team built tools that made it really easy for developers to measure the latency of their pages.

      2 replies 6 retweets 78 likes
      Show this thread
    4. Andrew Certain‏ @tacertain 25 May 2019
      • Report Tweet
      • Report NetzDG Violation

      That system, called PMET, let developers put little "start" and "stop" indicators in their code and then our system would scrape the logs and store the latency histograms in a database. If their page wasn't hitting SLA, they could drill down and figure out why.

      3 replies 3 retweets 107 likes
      Show this thread
    5. Andrew Certain‏ @tacertain 25 May 2019
      • Report Tweet
      • Report NetzDG Violation

      @dwagner00 wrote the prototype service for collecting and aggregating the data, and I wrote a simple visualization tool (using Perl and gnuplot). The rest is history!

      2 replies 2 retweets 77 likes
      Show this thread
    6. Andrew Certain‏ @tacertain 25 May 2019
      • Report Tweet
      • Report NetzDG Violation

      All things considered, it's probably the most-impactful thing I have done in my 20 years at Amazon, and I did it in my first few years! That focus on high percentiles instead of averages has driven so much good behavior.

      2 replies 19 retweets 252 likes
      Show this thread
    7. Andrew Certain‏ @tacertain 25 May 2019
      • Report Tweet
      • Report NetzDG Violation

      When James Hamilton started in AWS, we were chatting about PMET. When he heard that I had been one of the creators, he told me that when he read the Dynamo paper, the thing that had the biggest impact on his thinking from the paper was that we were focused on percentile latency.

      1 reply 3 retweets 100 likes
      Show this thread
    8. Andrew Certain‏ @tacertain 25 May 2019
      • Report Tweet
      • Report NetzDG Violation

      If you work at Amazon, you can hear me talk about this in an old PoA talk. If you search broadcast for "andrew certain gems" it should be the only hit (it's the first ten minutes of that video). That's it!

      5 replies 1 retweet 134 likes
      Show this thread
    9. John O'Shea‏ @joshea 25 May 2019
      • Report Tweet
      • Report NetzDG Violation
      Replying to @tacertain

      I'll have to find and add that video to the monitoring bootcamp! One set of stats that PMET didn't & CloudWatch don't (yet) offer are 'trimmed mean' stats, wondering if you'd every considered them? Seems like they'd compliment percentiles for use cases like observing page latency

      1 reply 0 retweets 1 like
    10. Andrew Certain‏ @tacertain 25 May 2019
      • Report Tweet
      • Report NetzDG Violation
      Replying to @joshea

      I hadn't. I'm very self-taught when it comes to statistics, so didn't have many tools in my toolbox! 😁

      2 replies 0 retweets 0 likes
      Colm MacCárthaigh‏ @colmmacc 25 May 2019
      • Report Tweet
      • Report NetzDG Violation
      Replying to @tacertain @joshea

      Related: overstats are an under appreciated gem!

      2:58 PM - 25 May 2019 from Seattle, WA
      • 2 Likes
      • Cameron Yule Andrew Certain
      2 replies 0 retweets 2 likes
        1. New conversation
        2. Stuart Marshall‏ @StuartHMarshall 25 May 2019
          • Report Tweet
          • Report NetzDG Violation
          Replying to @colmmacc @tacertain @joshea

          What are overstats? (I tried googling for the term, but it's buried in overwatch results.)

          1 reply 0 retweets 0 likes
        3. Colm MacCárthaigh‏ @colmmacc 25 May 2019
          • Report Tweet
          • Report NetzDG Violation
          Replying to @StuartHMarshall @tacertain @joshea

          A simple count of the number of data points over a given value. Eg the 1ms overstat counts every data point over 1ms.

          0 replies 0 retweets 2 likes
        4. End of conversation
        1. New conversation
        2. Joe Magerramov‏ @_joemag_ 25 May 2019
          • Report Tweet
          • Report NetzDG Violation
          Replying to @colmmacc @tacertain @joshea

          They are, but I haven’t seen anybody implement them well. Presumably because they are computationally expensive for non hard coded values?

          1 reply 0 retweets 0 likes
        3. Marc Brooker‏ @MarcJBrooker 25 May 2019
          • Report Tweet
          • Report NetzDG Violation
          Replying to @_joemag @colmmacc and

          Calculating overstats using an exponentially bucketed histogram (with bounded error) isn't too hard. O(N) in the number of buckets.

          1 reply 0 retweets 0 likes
        4. 2 more replies

      Loading seems to be taking a while.

      Twitter may be over capacity or experiencing a momentary hiccup. Try again or visit Twitter Status for more information.

        Promoted Tweet

        false

        • © 2020 Twitter
        • About
        • Help Center
        • Terms
        • Privacy policy
        • Imprint
        • Cookies
        • Ads info