ShadowDNS Startup Performance Benchmark¶

This document records how the --dry-run startup smoke test is run, along with sample output.

What Is `--dry-run`?¶

The --dry-run flag makes ShadowDNS execute the full loading process (parsing named.conf, reading all zone files, loading the GeoIP mmdb files), but exit and print a summary before starting the UDP/TCP listeners. It is suitable for:

Confirming the configuration file syntax is correct
Computing a memory baseline without affecting DNS service
A configuration validation step in CI/CD pipelines

Build Steps¶

# Run from the repo root
go build -o ./shadowdns ./cmd/shadowdns

Usage¶

./shadowdns \
    --named-conf /path/to/named.conf \
    --config     /path/to/shadowdns.yaml \
    --dry-run

On success it exits with code 0 and outputs:

level=INFO msg="dry-run: configuration loaded successfully" views=N zones=M

Automated Smoke Test Script¶

scripts/smoke.sh automates the following steps:

Build the binary
Copy testdata/integration/ to /tmp/shadowdns-smoke/, replacing TESTDATA_DIR_PLACEHOLDER
Generate test GeoIP mmdb files
Run --dry-run under /usr/bin/time, recording memory usage

./scripts/smoke.sh

Sample Output (2026-04-13, Apple Silicon, testdata/integration fixture)¶

Execution environment: macOS Darwin 24.6.0, Apple M-series, Go 1.25.6

time=2026-04-13T23:28:01.556+08:00 level=INFO msg="shadowdns starting" \
    named_conf=...named.conf config=...shadowdns.yaml listen=:53
time=2026-04-13T23:28:01.557+08:00 level=INFO msg="loaded GeoIP country database" \
    path=.../geoip/GeoLite2-Country.mmdb
time=2026-04-13T23:28:01.558+08:00 level=INFO msg="loaded GeoIP ASN database" \
    path=.../geoip/GeoLite2-ASN.mmdb
time=2026-04-13T23:28:01.558+08:00 level=INFO msg="dry-run: configuration loaded successfully" \
    views=2 zones=4
        0.31 real         0.00 user         0.01 sys
             8437760  maximum resident set size

Metric	Value
Load time (real)	0.31 s
Maximum RSS (maximum resident set size)	8,437,760 bytes (≈ 8.0 MB)
View count (views)	2
Loaded zone count (zones)	4

Notes¶

This fixture is tiny: only 2 views × 2 zones (1 root + 1 backup); memory is almost entirely consumed by the Go runtime.
Production-scale deployment estimate: based on the numbers in Context (3,600 root domains × 7 views, average zone size 10 KB), ShadowDNS is expected to load only root zones (no duplicate loading of backups), giving roughly 3,600 × 7 × 10 KB ≈ 252 MB plus the GeoIP mmdb files (about 60–80 MB), for a total of about 330–350 MB — roughly 45–50% savings compared with BIND's ~630 MB (including redundant backups).
Actual production memory must be measured with a production-scale configuration; --dry-run provides a baseline, and once actually listening, the Go runtime may grow slightly due to goroutine stacks and similar factors.
It is recommended to add a ./scripts/smoke.sh step in CI to ensure the configuration loads correctly after every merge.