The Ktistec executable is now ~24.7% smaller and build times are 28% faster.

I've been blogging about optimizations here, here, and here. This is the summary of the final outcome, with links to commits for the curious. I have one more post planned with a summary of my thoughts.

Here's my approach. Use nm to dump the symbols in a release build executable and then look for things that seem redundant. The first change and associated post below is a great example of what I mean—my original implementation led to the specialization of the #== method for every pairwise combination of model classes even though the result of the comparison was just false.

This might seem like a strange approach if you come from a compiled language where you mostly write all of the code yourself or invoke generics explicitly, but Crystal takes your code and does that for you. And it's not always obvious up front (to me, at least) what the final cost will be.

I've include counts of the lines added/removed because the point of this whole post is to say if you measure first and then optimize, a small change can have a big impact.

Here are the changes:

• Specialize model #==. (+7 -5)
  I talked about this here but didn't have the commit to link to. This change results in a large reduction in executable size on regular builds (~4.0%) and a small difference on release builds (~0.2%).
• Remove conversion to Hash. (+2 -2)
  This commit eliminates specialization of methods like __for_internal_use_only that get passed both named tuples and hashes by going all in with named tuples. It also eliminates instantiations of the Hash generic type itself for these cases. Reduces executable size by ~2.2%.
• Eliminate duplicate code in the executable. (+3 -3)
  This small change reduces the size of the executable by a further ~0.4% by eliminating redundant definitions of __for_internal_use_only entirely.
• Make InstanceMethods instance methods. (+1 -5)
  This was a goofy design I picked up somewhere. It's unnecessary. Changing this saves ~0.2% on release build executable size.
• Move the code for digging through JSON-LD. (+246 -281)
  It looks like a lot of lines of code changed here, but the large numbers are the result of moving code line-by-line from an included module to a utility class. Invoking these as methods on the utility class rather than as instance methods on each including class reduces the executable size by ~0.5%.
• Use map from base ActivityPub model classes. (+10 -2)
  map is a class method defined on each ActivityPub base model class. Each definition maps JSON-LD to a hash that is used to instantiate the class. Class methods defined on a base class are available on subclasses, as well. Calling the method on the subclass results in a copy of the method. This change reduces the executable size by ~5.8%.
• Move map into helper. (+104 -88)
  The map method does not depend on class/instance state. This change ensures that the mapping code is not duplicated even if a subclass's map method is accidentally again called. It looks like a lot of changes but this commit is mostly reorganization. It reduces executable size by ~0.4%.
• Replace classes with aliases. (+62 -148)
  Implementing ActivityPub's vocabulary with discrete model classes is expensive because every model class comes with machinery for type-specific CRUD operations. Enumerate aliases on each base model class (e.g. a "Service" is an "Actor"). This change reduces executable size by ~16.9%.

I'm off to optimize some queries now...

#ktistec #crystallang

Specialize model `#==`. · toddsundsted/ktistec@aeb3466

Being explicit makes a large reduction in executable size on regular builds (~4.0%) and a small difference on release builds (~0.2%).

^GitHub

Todd Sundsted

2025-01-02 13:31:33

After I release a new version of ktistec, I build the server commit-by-commit to see which commits increase the server executable size and build time the most. I do this because I’ve learned that small implementation details (inlined code, small methods, using blocks) can have large impacts on these numbers.

Here's the output:
Commit Size Time
======== ========== ======= ===== =======
248850b1 36426264 10.3
47268073 36425688 -0.00% 10.5 +1.60%
344de272 36425688 +0.00% 10.8 +3.24%
ef561f52 36425944 +0.00% 10.8 -0.08%
8ae2cbd4 36429128 +0.01% 10.8 -0.01%
3e425f3b 36429128 +0.00% 10.8 +0.22%
1487d903 36427704 -0.00% 11.0 +1.42%
935c9ceb 36427016 -0.00% 11.0 +0.14%
de37dc6a 36427016 +0.00% 10.9 -0.97%
a660a326 36427016 +0.00% 10.8 -1.12%
ff3d990e 36427016 +0.00% 10.8 +0.54%
5724a58d 36523192 +0.26% 11.0 +1.78%
7b5057d4 36523640 +0.00% 11.0 -0.44%
30ca6a3f 36541352 +0.05% 11.6 +5.73%
e2327eea 36671592 +0.36% 11.0 -5.36%
ad0d76eb 36671592 +0.00% 10.9 -0.48%
d388e74f 36671592 +0.00% 11.4 +4.59%
dacea7ad 36671592 +0.00% 11.0 -3.76%
03d5dfd8 36671592 +0.00% 10.8 -1.63%
79d9d89f 36671576 -0.00% 11.0 +1.82%
b65d292f 36792376 +0.33% 11.1 +0.95%
0ef53365 36808904 +0.04% 11.6 +4.88%
b3766e7b 36808904 +0.00% 11.1 -4.50%
56ba79ce 36825416 +0.04% 11.1 -0.50%
4824df58 36825736 +0.00% 11.1 +0.31%
c4705143 36837544 +0.03% 11.1 -0.03%
e3d37ef7 36837768 +0.00% 11.5 +3.52%
4509fa0d 36837768 +0.00% 11.0 -3.83%
0ff9237b 36837768 +0.00% 11.0 -0.55%
Overall, the server executable size increased by about 1.1% and the build time increased by about 6.8%. Maybe that's not too bad for a major feature, but let's dig in.

It's nice to see that three commits account for almost all of the increase in server executable size:

• 5724a58d Add `language` to `Object`.
  2 files +19 loc
• e2327eea Render `contentMap` on ActivityPub objects.
  2 files +17 -1 loc
• b65d292f Add translation actions to the objects controller.
  1 file +35 loc

But, compare 5724a58d to 8ae2cbd4 (Add `language` to `Account`). It added +22 loc but didn't increase the server executable size as much.

In any case, I'll look at e2327eea first. I'd like to understand why this relatively small change adds 130,240 bytes to the server executable size!

The follow ups are here and here and here.

#ktistec #crystallang

GitHub - toddsundsted/ktistec: Single user ActivityPub (www.w3.org/TR/activitypub/) server.

Single user ActivityPub (https://www.w3.org/TR/activitypub/) server. - toddsundsted/ktistec

^GitHub