PUBLIC MARKS from night.kame with tag performance

Empirical studies have shown that human beings cannot normally perceive changes in numeric data (e.g. price movements) occurring more frequently than once every 200ms.

Consequently for applications that have a human as their primary user, a useful rule of thumb is that Stop-The-World (STW) pause of 200ms or under is usually of no concern. Some applications (e.g. streaming video) need lower GC jitter than this, but many GUI applications will not.

Voilà, pas la peine de tuer la machine à rafraichir trop souvent, 5Hz ça suffit.

After more research and swapping out modules, the bottleneck was narrowed down to the Sequelize ORM. A direct correlation was identified between the number of records and the throughput from the resource. By increasing the number of records in a table, it exponentially decreased the throughput of data when using Sequelize.

On comprend mieux pourquoi les révolutionnaires se concentrent sur le NoSQL : c'est qu'ils ont du mal avec le SQL :-)

Node.js wasn’t selected because it is easier to scale the team with a JVM base. Node.js isn’t developed enough to have standards and best practices, a large volume of well tested code. With Scala you can use all the Java code. There’s not a lot of knowledge of how to use it in a scalable way and they target 5ms response times, 4 9s HA, 40K requests per second and some at 400K requests per second. There’s a lot in the Java ecosystem they can leverage.

What!?

600 Tweets per second!?

...

Wow... I'm more than incredibly underwhelmed... I mean I kind of imagined Twitter had all these scalability problems to solve because they had thousands or maybe even hundred thousands of tweets per second.

Heureusement, les places de marché n'ont pas attendu Ruby pour être développées... (hop un lien pour donner un ordre de grandeur (note : mps = messages par seconde)