pprof-diff

Diff two Go heap profiles and see what grew, what shrank, and what disappeared. One command, plain text (plus optional JSON and HTML).

pprof-diff before.prof after.prof --top 20 --by leaf

pprof-diff
==========

Top regressions (bytes)
-----------------------
  1  main.leaky                                        +120.0 KiB bytes       +30 objs

Top improvements (bytes)
------------------------
(none)

Disappeared since before
------------------------
  1  runtime.mallocgc                                    -512 B bytes        -2 objs

New since before
----------------
  1  bufio.NewReaderSize                               +24.0 KiB bytes        +6 objs

Why this exists

go tool pprof -base=before after is the right tool for interactive investigation. pprof-diff is for when you want a fixed report: paste into a PR, gate CI on a text diff, or answer "what changed?" without opening the pprof TUI.

	pprof-diff	go tool pprof -base
Text diff report	yes	via top / export
JSON / static HTML / web viewer	yes	no
Flame graphs	no	yes
Single static binary	yes (D)	via Go install

Install

Requires DMD 2.111+ and DUB.

git clone https://github.com/1rhino2/pprof-diff.git
cd pprof-diff
dub build --build=release

Binary: .dub/pprof-diff.exe (path varies by platform) or run with dub run --.

Usage

pprof-diff before.prof after.prof [options]

Option	Default	Description
--top N	20	Max rows per section
--by stack	stack	Group by full stack, leaf, or rough type
--json path		Write machine-readable diff
--html path		Write single-page HTML table

Web viewer

Live demo: https://1rhino2.github.io/pprof-diff/

1. Run pprof-diff before.prof after.prof --json report.json
2. Open the site and choose Open diff.json, or use Load demo

The site only reads JSON produced by the CLI (no .prof upload in the browser).

Synthetic examples (repo)

dub run --config=gen-examples
dub run -- examples/before.prof examples/after.prof --top 10
dub run -- examples/before.prof examples/after.prof --html examples/report.html --json examples/diff.json

Real Go heap profiles

cd examples/go
go run leak.go
cd ../..
dub run -- examples/go/before.prof examples/go/after.prof --by leaf

From tests or production:

go test -memprofile=before.prof -run=YourBench .
# change code
go test -memprofile=after.prof -run=YourBench .
pprof-diff before.prof after.prof --top 30

Profiles must be pprof protobuf (gzip-compressed .prof from Go is supported).

How it works

1. Gunzip if the file starts with 1F 8B.
2. Decode the Profile message (subset of google/pprof; unknown fields skipped).
3. Pick inuse_objects / inuse_space columns when present.
4. Aggregate by stack key, diff before vs after, sort by byte delta.

See proto/profile.proto for the wire schema.

Development

.\build.ps1          # release build, tests, regenerate examples
dub run --config=golden-test

Limits

• Optimized for heap profiles (object count + bytes). CPU and other profile types are best-effort.
• Symbol quality depends on the profile (stripped binaries give weaker names).
• For deep dives, use go tool pprof.

License

MIT. See LICENSE.