ReactiveConf
1 HN recommender · recommended in 3 months, 2018–2019
33:23 · 2.9K views · Nov 20, 2017
Tom Dale explains the internals of the Glimmer VM, Ember's rendering engine, which compiles templates to opcodes. The talk includes a performance benchmark demo.
HN points to it for understanding Glimmer and Ember's view layer, and as a reference for opcode-compiled templates.
3 comments from Hacker News
Ember is the PostgreSQL of JavaScript frameworks. Similar to the way Postgres has deep roots that trace back to Ingres[1] in the days before SQL was a solidly established standard, Ember traces it roots back to SproutCore[2] in the JS framework pre-historic era of 2010. And the same way PostgreSQL was seen as a second-tier or only "historically significant" open source database, the PostgreSQL team just kept at it, toiling away year after year, steading churning out awesome code and excellent documentation, getting better and better with each release. Like clockwork. In the same way PostgreSQL is now, finally, enjoying more popularity and getting the recognition (long overdue in my opinion) for the awesome platform that it is, I expect that in time more developers will come around to appreciating Ember. The Ember leadership is definitely approaching the project and the processes around it like they intend to be not just relevant but pushing the boundaries for a long time to come. For one example this boundary pushing, you should not miss @tomdale's talk at ReactConf about GlimmerJS (the view layer extracted from EmberJS). It is, in my humble opinion, simultaneously mind-blowing and and inspiring.[3] [1] [LINK] [2] [LINK] [3] this video
This is a good development. Honestly one thing I very much think is a downside about React is the fact that your template is also JavaScript. Don't get me wrong this is incredibly powerful and can be very expressive, but it comes at a cost. That cost has the same cost as other JavaScript - it's blocking, cannot be paused and has all the possibilities of de-optimizations that might occur in the JIT. The Ember team faced a similar problem in the past and I find their solution to this problem quite intriguing, even in it's obscurity. Instead of compiling their templates to JavaScript they instead compile them to opcodes in a binary format which is executed by a virtual machine. This has several advantages. Since the template file is represented as an optimized binary the size of the file itself is incredibly small, excellent since templates can be a large part of your eventual code. Not only that but since the instructions are opcodes, this mean the VM can pause at a moment when the browser is too busy with other stuff. Since a large part of your templates is probably static and not prone to any changes the template file also indicates which parts of the instructions are dynamic and which are static. This allows the VM to generate a separate set of instructions just for subsequent updates, only updating those parts which are dynamic. Now I am not saying this is a silver bullet, it is however an interesting and fresh approach. In case you're interested in this check out the Glimm
Yes, the runtime needs to be JavaScript. It’s not obviously faster, but it’s been benchmarked to be faster. this video You can skip to 29:34 for the performance demo.