golang/go

x/net/trace: dependency on html/template inhibits dead code elimination

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#62,024 opened on Aug 14, 2023

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Description

Any use of reflect.Value.MethodByName() or reflect.Type.MethodByName() disables the DCE. The compiler assumes that these functions will look any method up, and cannot remove methods even if they are never called.

text/template and html/template are very notable offenders in this respect. They call MethodByName() on random strings extracted from template texts.

The package x/net/trace uses html/template, hence any user of x/net/trace compiles with DCE disabled. Worse yet, the package's init() references html/template which disables DCE even if x/net/trace is imported, but otherwise unused.

There is a very popular user of x/net/trace, namely google.golang.org/grpc. Essentially, this means that a lot of networked services in golang are compiled without DCE.

What did you expect to see?

I expect that a low-level library that is used by almost everyone does not pessimise the code generation by disabling the DCE. I'd avoid html/template altogether.

Contributor guide

Research direction
Investigate alternatives to html/template in x/net/trace that avoid calling reflect.MethodByName, such as using text/template with a restricted set of functions or writing a custom template parser. Also check how other projects like gRPC handle this.
Tech stack
go
Domain
backend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
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Active
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Clear
Prerequisites
Go
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
20