Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Add support for lazy matchers #185

Merged
merged 1 commit into from
Feb 18, 2024
Merged

Conversation

masklinn
Copy link
Contributor

@masklinn masklinn commented Feb 13, 2024

Support is addef for lazy builtin matchers (with a separately compiled file), as well as loading json or yaml files using lazy matchers.

Lazy matchers are very much a tradeoff: they improve import speed, but slow down run speed, possibly dramatically.

Use them by default for the re2 parser, but not the basic parser: experimentally, on Python 3.11

  • importing the package itself takes ~36ms
  • importing the lazy matchers takes ~36ms (including the package, so ~0)
  • importing the eager matchers takes ~97ms

the eager matchers have a significant overhead, however running the bench on the sample file, they cause a runtime increase of 700~800ms on the basic parser bench, as that ends up instantiating every regex (likely due to match failures). Relatively this is not huge (~2.5%), but the tradeoff doesn't seem great, especially since the parser itself is initialized lazily.

The re2 parser does much better, only losing 20~30ms (~1%), this is likely because it only needs to compile a fraction of the regexes (156 out of 1162 as of regexes.yaml version 0.18), and possibly because it gets to avoid some of the most expensive to compile ones.

TODO:

  • test the lazy matchers
  • note the space overhead of the additional precompiled file (compression level 77% in wheel file, 27783 bytes stored, 123017 raw)
  • note the memory overhead of the additional precompiled file
    turns out the eagerly compiled regex likely consume a bunch of memory,
    • loading _matchers.py adds 760~780k to the process
    • loading _lazy.py adds 65~75k (depends on loading order, likely because the literal strings are shared), forcing all the regexes to be compiled increases memory use by ~800k so that tracks
      the literal strings are likely shared but the compiled regex definitely are not, could have a shared cache but the use case of loading multiple builtin sets in actual production seems unlikely

@masklinn masklinn force-pushed the lazy-matchers branch 2 times, most recently from 51d1d6f to bdc33fd Compare February 17, 2024 19:25
Add lazy builtin matchers (with a separately compiled file), as well
as loading json or yaml files using lazy matchers.

Lazy matchers are very much a tradeoff: they improve import speed (and
memory consumption until triggered), but slow down run speed, possibly
dramatically:

- importing the package itself takes ~36ms
- importing the lazy matchers takes ~36ms (including the package, so
  ~0) and ~70kB RSS
- importing the eager matchers takes ~97ms and ~780kB RSS
- triggering the instantiation of the lazy matchers adds ~800kB RSS
- running bench on the sample file using the lazy matcher has
  700~800ms overhead compared to the eager matchers

While the lazy matchers are less costly across the board until they're
used, benching the sample file causes the loading of *every* regex --
likely due to matching failures -- has a 700~800ms overhead over eager
matchers, and increases the RSS by ~800kB (on top of the original 70).

Thus lazy matchers are not a great default for the basic parser.
Though they might be a good opt-in if the user only ever uses one of
the domains (especially if it's not the devices one as that's by far
the largest).

With the re2 parser however, only 156 of the 1162 regexes get
evaluated, leading to a minor CPU overhead of 20~30ms (1% of bench
time) and a more reasonable memory overhead. Thus use the lazy matcher
fot the re2 parser.

On the more net-negative but relatively minor side of things, the
pregenerated lazy matchers file adds 120k to the on-disk requirements
of the library, and ~25k to the wheel archive. This is also what the
_regexes and _matchers precompiled files do. pyc files seem to be even
bigger (~130k) so the tradeoff is dubious even if they are slightly
faster.

Fixes ua-parser#171, fixes ua-parser#173
@masklinn masklinn enabled auto-merge (rebase) February 18, 2024 19:14
@masklinn masklinn merged commit 16c1324 into ua-parser:master Feb 18, 2024
29 checks passed
@masklinn masklinn deleted the lazy-matchers branch February 19, 2024 18:56
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
None yet
Projects
None yet
Development

Successfully merging this pull request may close these issues.

1 participant