commit: 9d98477ca922253e1db5ec213a188927385d25db
[log]
author: Tony Liao <tonyliaoss@google.com>
Tue Aug 25 07:03:34 2026 -0700
committer: Copybara-Service <copybara-worker@google.com>
Tue Aug 25 07:09:41 2026 -0700
tree: 6ae1d910793ae070fcd47fe48e1b0978a67b7311
parent: 7f86060aae572ca1aab356712d3d3a433e13565a [diff]

Optimize pure Python parse path for custom JSON enum names.

This implementation is similar to our Java idea in cl/949670944,
basically the idea is that we will have a local map (dictionary) that
will be populated the very first time we try to parse into an enum
field. The lifetime of this dictionary will be tied to the Parser
instance, similar to the Java implementation.

BENCHMARKS (baseline stats are recorded at cl/952170250):

Python:
```
[BENCHMARK] ParseJsonDefault:                med 10.06 us/op | p99 11.22 us/op | mean 10.10 ± 0.20 us/op
[BENCHMARK] ParseJsonCustom:                 med 20.33 us/op | p99 22.23 us/op | mean 20.40 ± 0.34 us/op
[BENCHMARK] ParseJsonUnknownIgnored:         med 24.21 us/op | p99 26.25 us/op | mean 24.31 ± 0.44 us/op
[BENCHMARK] ParseRepeatedJsonDefault:        med 1.94 us/item | p99 2.05 us/item | mean 1.95 ± 0.03 us/item
[BENCHMARK] ParseRepeatedJsonCustom:         med 2.26 us/item | p99 2.45 us/item | mean 2.27 ± 0.03 us/item
[BENCHMARK] ParseRepeatedJsonUnknownIgnored: med 5.31 us/item | p99 5.52 us/item | mean 5.32 ± 0.05 us/item
```

Cpp:
```
[BENCHMARK] ParseJsonDefault:                med 8.66 us/op | p99 9.21 us/op | mean 8.70 ± 0.13 us/op
[BENCHMARK] ParseJsonCustom:                 med 26.33 us/op | p99 29.71 us/op | mean 26.44 ± 0.69 us/op
[BENCHMARK] ParseJsonUnknownIgnored:         med 28.46 us/op | p99 31.80 us/op | mean 28.59 ± 0.67 us/op
[BENCHMARK] ParseRepeatedJsonDefault:        med 1.72 us/item | p99 2.19 us/item | mean 1.74 ± 0.06 us/item
[BENCHMARK] ParseRepeatedJsonCustom:         med 2.12 us/item | p99 2.38 us/item | mean 2.13 ± 0.04 us/item
[BENCHMARK] ParseRepeatedJsonUnknownIgnored: med 4.61 us/item | p99 4.92 us/item | mean 4.62 ± 0.07 us/item
```

UPB:
```
[BENCHMARK] ParseJsonDefault:                med 11.22 us/op | p99 12.29 us/op | mean 11.27 ± 0.21 us/op
[BENCHMARK] ParseJsonCustom:                 med 37.54 us/op | p99 39.25 us/op | mean 37.65 ± 0.46 us/op
[BENCHMARK] ParseJsonUnknownIgnored:         med 41.18 us/op | p99 48.45 us/op | mean 41.30 ± 0.89 us/op
[BENCHMARK] ParseRepeatedJsonDefault:        med 2.10 us/item | p99 2.19 us/item | mean 2.10 ± 0.02 us/item
[BENCHMARK] ParseRepeatedJsonCustom:         med 2.58 us/item | p99 2.73 us/item | mean 2.59 ± 0.03 us/item
[BENCHMARK] ParseRepeatedJsonUnknownIgnored: med 5.70 us/item | p99 5.90 us/item | mean 5.71 ± 0.04 us/item
```

Seeing these benchmarks, we can see a very noticeable improvement in
`ParseRepeatedJsonCustom` and `ParseRepeatedJsonUnknownIgnored` cases --
which correspond to the pathological cases that we are worried about.
Singular fields are taking longer to parse in our microbenchmark because
the cache that we've added is tied to each Parser instance and must be
re-instantiated across every `Parse` call.

PiperOrigin-RevId: 970528683

2 files changed

tree: 6ae1d910793ae070fcd47fe48e1b0978a67b7311

README.md

Protocol Buffers - Google's data interchange format

Overview

Protocol Buffers (a.k.a., protobuf) are Google's language-neutral, platform-neutral, extensible mechanism for serializing structured data. You can learn more about it in protobuf's documentation.

This README file contains protobuf installation instructions. To install protobuf, you need to install the protocol compiler (used to compile .proto files) and the protobuf runtime for your chosen programming language.

Working With Protobuf Source Code

Most users will find working from supported releases to be the easiest path.

If you choose to work from the head revision of the main branch your build will occasionally be broken by source-incompatible changes and insufficiently-tested (and therefore broken) behavior.

If you are using C++ or otherwise need to build protobuf from source as a part of your project, you should pin to a release commit on a release branch.

This is because even release branches can experience some instability in between release commits.

Bazel with Bzlmod

Protobuf supports Bzlmod with Bazel 8 +. Users should specify a dependency on protobuf in their MODULE.bazel file as follows.

bazel_dep(name = "protobuf", version = <VERSION>)

Users can optionally override the repo name, such as for compatibility with WORKSPACE.

bazel_dep(name = "protobuf", version = <VERSION>, repo_name = "com_google_protobuf")

Bazel with WORKSPACE

Users can also add the following to their legacy WORKSPACE file.

Note that with the release of 30.x there are a few more load statements to properly set up rules_java and rules_python.

http_archive(
    name = "com_google_protobuf",
    strip_prefix = "protobuf-VERSION",
    sha256 = ...,
    url = ...,
)

load("@com_google_protobuf//:protobuf_deps.bzl", "protobuf_deps")

protobuf_deps()

load("@rules_java//java:rules_java_deps.bzl", "rules_java_dependencies")

rules_java_dependencies()

load("@rules_java//java:repositories.bzl", "rules_java_toolchains")

rules_java_toolchains()

load("@rules_python//python:repositories.bzl", "py_repositories")

py_repositories()

Protobuf Compiler Installation

The protobuf compiler is written in C++. If you are using C++, please follow the C++ Installation Instructions to install protoc along with the C++ runtime.

For non-C++ users, the simplest way to install the protocol compiler is to download a pre-built binary from our GitHub release page.

In the downloads section of each release, you can find pre-built binaries in zip packages: protoc-$VERSION-$PLATFORM.zip. It contains the protoc binary as well as a set of standard .proto files distributed along with protobuf.

If you are looking for an old version that is not available in the release page, check out the Maven repository.

These pre-built binaries are only provided for released versions. If you want to use the github main version at HEAD, or you need to modify protobuf code, or you are using C++, it's recommended to build your own protoc binary from source.

If you would like to build protoc binary from source, see the C++ Installation Instructions.

Protobuf Runtime Installation

Protobuf supports several different programming languages. For each programming language, you can find instructions in the corresponding source directory about how to install protobuf runtime for that specific language:

Language	Source
C++ (include C++ runtime and protoc)	src
Java	java
Python	python
Objective-C	objectivec
C#	csharp
Ruby	ruby
Go	protocolbuffers/protobuf-go
PHP	php
Dart	dart-lang/protobuf
JavaScript	protocolbuffers/protobuf-javascript

Quick Start

The best way to learn how to use protobuf is to follow the tutorials in our developer guide.

If you want to learn from code examples, take a look at the examples in the examples directory.

Documentation

The complete documentation is available at the Protocol Buffers doc site.

Support Policy

Read about our version support policy to stay current on support timeframes for the language libraries.

Developer Community

To be alerted to upcoming changes in Protocol Buffers and connect with protobuf developers and users, join the Google Group.