Use frozen string literals

[technicalpickles]

I've been using memory_profiler on an extremely slow Rails system spec, and was surprised to see net/http came up in it. This particular test does an absolute ton of HTTP requests though.

I was looking through this code, and realized there's a lot of string literals used in some of the hot code paths, but frozen_string_literal had been explicitly set to false. There was only a few small changes after turning frozen_string_literal on to get the suite passing.

I tested my app against this, and it shaved off some 23s, from 2m15s to 1m52s 😱

I'll post before/after of the memory_profiler reports shortly.

[technicalpickles]

Below is the relevant bits from a memory_profiler report. The tl;dr:

• total allocated
  • memory: 10% reduction
  • objects: 7% reduction

Before

Total allocated: 5_363_399_946 bytes (45_328_676 objects)
Total retained: 180_774_831 bytes (1_244_196 objects)

allocated memory by file

96815592 /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/header.rb

allocated objects by file

1675464 /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/header.rb
330298 /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/response.rb
268506 /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/generic_request.rb

Allocated String Report

322618  "-"
 54114  /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/header.rb:486

318394  " "
 16247  /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/response.rb:175


187484  ""
 27071  /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/response.rb:173

154335  ", "
 55180  /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/header.rb:218
 54114  /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/header.rb:479

148148  "\n"
 21659  /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/response.rb:173

121761  "Content-Type"
 19476  /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/header.rb:713
 19476  /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/header.rb:728
  5411  /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/response.rb:180
  5409  /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/header.rb:486

 92393  "\r\n"
 43334  /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/header.rb:270
 27058  /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/header.rb:192
  5412  /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/generic_request.rb:329
  5412  /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/generic_request.rb:333
  5412  /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/response.rb:173


 82734  "content-type"
 38952  /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/header.rb:217
  5412  /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/header.rb:273
  5411  /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/header.rb:254
  5409  /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/generic_request.rb:38
  5409  /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/header.rb:195
  5409  /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/header.rb:456

 80881  "Content-Length"
  5412  /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/response.rb:180
  5410  /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/header.rb:609
  5410  /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/header.rb:610
  4329  /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/header.rb:486

 71402  ";"
 19476  /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/header.rb:713
 19476  /Users/josh.nichols/.rbenv/versions/3.2.2/lib/ruby/3.2.0/net/http/header.rb:728

After

Total allocated: 4_795_299_370 bytes (42_124_716 objects)
Total retained: 169_143_871 bytes (1_109_228 objects)

allocated memory by file

68355240 /Users/josh.nichols/workspace/net-http/lib/net/http/header.rb

allocated objects by file

1038079 /Users/josh.nichols/workspace/net-http/lib/net/http/header.rb
191421 /Users/josh.nichols/workspace/net-http/lib/net/http/response.rb

Allocated String Report

168326  "-"
        (nothing from net-http)

320917  " "
        (nothing from net-http)

138990  ""
  4251  /Users/josh.nichols/workspace/net-http/lib/net/http/response.rb:173


154335  ", "
        (nothing from net-http)

128933  "\n"
        (nothing from net-http)

 42489  "Content-Type"
  4250  /Users/josh.nichols/workspace/net-http/lib/net/http/response.rb:180
  4248  /Users/josh.nichols/workspace/net-http/lib/net/http/header.rb:494


     0  "\r\n"
        (nothing from net-http)

 65232  "content-type"
 30660  /Users/josh.nichols/workspace/net-http/lib/net/http/header.rb:225
  4251  /Users/josh.nichols/workspace/net-http/lib/net/http/header.rb:281
  4250  /Users/josh.nichols/workspace/net-http/lib/net/http/header.rb:262
  4248  /Users/josh.nichols/workspace/net-http/lib/net/http/generic_request.rb:42
  4248  /Users/josh.nichols/workspace/net-http/lib/net/http/header.rb:203
  4248  /Users/josh.nichols/workspace/net-http/lib/net/http/header.rb:464

 37507  "Content-Length"
  4251  /Users/josh.nichols/workspace/net-http/lib/net/http/response.rb:180
  3417  /Users/josh.nichols/workspace/net-http/lib/net/http/header.rb:494


     0  ";"
        (nothing from net-http)

[yuki24]

Thank you!

[natematykiewicz]

Thanks for marking me as a co-author @technicalpickles!