varnish: remove thread pool overrides, use built-in defaults by gquintard · Pull Request #1350 · MDA2AV/HttpArena

gquintard · 2026-08-27T21:42:19Z

Summary

thread_pool_max=10000/thread_pool_min=5000 (x2 pools = up to ~20k threads) is wildly oversized for the 64-logical-CPU cpuset the benchmark container runs on for CPU-bound synthetic responses. This strips the override to get a clean varnishd-defaults baseline before sweeping custom pool sizes.
Fixes a missing line-continuation after vsl_mask=none that made -s malloc,256m dead code, never reaching varnishd.

Test plan

Re-run baseline/pipelined/limited-conn benchmark profiles against this branch
Compare RPS and varnishstat thread/queue counters (MAIN.sess_queued, MAIN.threads_limited) against current main

thread_pool_max=10000/min=5000 (x2 pools = up to ~20k threads) is wildly oversized for a 64-logical-CPU container running CPU-bound synthetic responses. Strip it to get a clean varnishd-defaults baseline before sweeping custom pool sizes. Also fixes a missing line-continuation after vsl_mask=none that made -s malloc,256m dead code, never reaching varnishd. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

github-actions · 2026-08-27T21:42:33Z

👋 Heads up! This PR modifies the following frameworks:

varnish → @guillaume.quintard@varnish-software.com

gquintard · 2026-08-27T21:44:50Z

/benchmark -f varnish --save

github-actions · 2026-08-27T21:44:59Z

👋 Benchmark request received. A collaborator will review and approve the run.

github-actions · 2026-08-28T04:38:22Z

Benchmark Results

Framework: varnish | Test: all tests

Test	Conn	RPS	CPU	Mem	Δ RPS	Δ Mem
baseline	512	196,839	6497.5%	200MiB	-4.6%	-63.0%
baseline	4096	184,587	6341.9%	182MiB	-9.8%	-78.5%
pipelined	512	301,028	6532.3%	161MiB	-4.3%	-67.9%
pipelined	4096	293,014	6514.7%	297MiB	+3.3%	-77.7%
limited-conn	512	176,954	6421.4%	222MiB	+0.7%	-61.5%
limited-conn	4096	175,270	6507.5%	406MiB	-7.5%	-48.3%
baseline-h2	256	209,753	6377.8%	2.4GiB	-1.9%	-46.7%
baseline-h2	1024	204,798	6146.1%	2.5GiB	-0.7%	-47.9%
static-h2	256	152,265	6443.2%	1.9GiB	+0.5%	-13.6%
static-h2	1024	148,173	6377.2%	2.4GiB	+5.4%	-48.9%

Full log

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21. Stopping all clients.
9. Stopping all clients.
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46. Stopping all clients.

finished in 5.05s, 143696.40 req/s, 8.55GB/s
requests: 807981 total, 838905 started, 807981 done, 718482 succeeded, 89499 failed, 89499 errored, 0 timeout
status codes: 733615 2xx, 0 3xx, 0 4xx, 0 5xx
traffic: 42.77GB (45925187992) total, 124.94MB (131006022) headers (space savings 21.18%), 42.62GB (45757902539) data
                     min         max         mean         sd        +/- sd
time for request:     1.51ms       1.07s     67.22ms     36.92ms    95.97%
time for connect:     3.07ms       1.03s    352.07ms    335.51ms    68.85%
time to 1st byte:    10.35ms       1.06s    428.22ms    336.46ms    52.36%
req/s           :       0.00      594.40      290.35      117.98    64.94%
[info] CPU 6484.5% | Mem 2.6GiB

=== Best: 148173 req/s (CPU: 6377.2%, Mem: 2.4GiB) ===
[info] saved results/static-h2/1024/varnish.json
httparena-bench-varnish
httparena-bench-varnish
[info] skip: varnish does not subscribe to baseline-h2c
[info] skip: varnish does not subscribe to json-h2c
[info] skip: varnish does not subscribe to baseline-h3
[info] skip: varnish does not subscribe to static-h3
[info] skip: varnish does not subscribe to gateway-64
[info] skip: varnish does not subscribe to gateway-h3
[info] skip: varnish does not subscribe to production-stack
[info] skip: varnish does not subscribe to unary-grpc
[info] skip: varnish does not subscribe to unary-grpc-tls
[info] skip: varnish does not subscribe to echo-ws
[info] skip: varnish does not subscribe to echo-ws-pipeline
[info] skip: varnish does not subscribe to echo-ws-limited
[info] skip: varnish does not subscribe to latency-1m
[info] skip: varnish does not subscribe to async
[info] rebuilding site/data/*.json
[updated] /home/diogo/actions-runner/_work/HttpArena/HttpArena/site/data/frameworks.json
[updated] /home/diogo/actions-runner/_work/HttpArena/HttpArena/site/data/results/varnish.json - 10 new, 10 total
[updated] /home/diogo/actions-runner/_work/HttpArena/HttpArena/site/data/current.json
[info] done
[info] restoring loopback MTU to 65536

Explicit config replacing bare defaults: more pools to reduce cross-CCX lock/cache-line contention on the Threadripper's multi-CCX layout, sized well below the original 5000/10000 min/max but above varnishd's built-in defaults. Also fixes a missing line-continuation after vsl_mask=none that made -s malloc,256m dead code, never reaching varnishd. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

gquintard · 2026-08-31T22:43:48Z

/benchmark -f varnish --save

github-actions · 2026-08-31T22:43:55Z

👋 Benchmark request received. A collaborator will review and approve the run.

github-actions · 2026-08-31T22:44:13Z

⚠️ /benchmark --save cannot start: main has diverged and cannot be auto-merged into this branch. Please merge or rebase main manually, push, and re-run /benchmark --save.

MDA2AV · 2026-08-31T22:53:41Z

/benchmark -f varnish --save

github-actions · 2026-08-31T22:53:49Z

👋 Benchmark request received. A collaborator will review and approve the run.

github-actions · 2026-08-31T22:58:10Z

Benchmark Results

Framework: varnish | Test: all tests

Test	Conn	RPS	CPU	Mem	Δ RPS	Δ Mem
baseline	4096	182,392	6393.3%	792MiB	-10.9%	-6.3%
pipelined	4096	282,924	6534.3%	1.1GiB	-0.3%	-15.4%
limited-conn	4096	158,846	6254.2%	1.4GiB	-16.2%	+82.6%
baseline-h2	256	214,862	6340.3%	3.4GiB	+0.5%	-24.4%
baseline-h2	1024	204,833	6418.6%	3.6GiB	-0.7%	-25.0%
static-h2	256	155,275	6538.3%	2.4GiB	+2.5%	+9.1%
static-h2	1024	147,407	6595.6%	3.8GiB	+4.8%	-19.1%

Full log

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63. Stopping all clients.
23
. Stopping all clients.


20Stopped all clients for thread #14
25. Stopping all clients.
20
. Stopping all clients.

finished in 5.05s, 145803.00 req/s, 8.67GB/s
requests: 815608 total, 845758 started, 815608 done, 729015 succeeded, 86593 failed, 86593 errored, 0 timeout
status codes: 743535 2xx, 0 3xx, 0 4xx, 0 5xx
traffic: 43.37GB (46568705380) total, 126.29MB (132428389) headers (space savings 21.23%), 43.21GB (46399557127) data
                     min         max         mean         sd        +/- sd
time for request:     2.87ms       1.27s    100.88ms     41.10ms    84.78%
time for connect:     3.60ms       1.28s    429.76ms    381.54ms    51.86%
time to 1st byte:    13.78ms       1.33s    490.24ms    388.27ms    52.72%
req/s           :       0.00      624.82      229.72      112.11    70.90%
[info] CPU 6490.0% | Mem 4.0GiB

=== Best: 147407 req/s (CPU: 6595.6%, Mem: 3.8GiB) ===
[info] saved results/static-h2/1024/varnish.json
httparena-bench-varnish
httparena-bench-varnish
[info] skip: varnish does not subscribe to baseline-h2c
[info] skip: varnish does not subscribe to json-h2c
[info] skip: varnish does not subscribe to baseline-h3
[info] skip: varnish does not subscribe to static-h3
[info] skip: varnish does not subscribe to gateway-64
[info] skip: varnish does not subscribe to gateway-h3
[info] skip: varnish does not subscribe to production-stack
[info] skip: varnish does not subscribe to unary-grpc
[info] skip: varnish does not subscribe to unary-grpc-tls
[info] skip: varnish does not subscribe to echo-ws
[info] skip: varnish does not subscribe to echo-ws-pipeline
[info] skip: varnish does not subscribe to echo-ws-limited
[info] skip: varnish does not subscribe to latency-1m
[info] skip: varnish does not subscribe to latency-10k
[info] skip: varnish does not subscribe to async
[info] rebuilding site/data/*.json
[updated] /home/diogo/actions-runner/_work/HttpArena/HttpArena/site/data/frameworks.json
[updated] /home/diogo/actions-runner/_work/HttpArena/HttpArena/site/data/results/varnish.json - 7 new, 7 total
[updated] /home/diogo/actions-runner/_work/HttpArena/HttpArena/site/data/current.json
[info] done
[info] restoring loopback MTU to 65536

gquintard · 2026-09-01T14:46:47Z

this confirms that tweaking the thread pools doesn't do much, and is even harmful. Closing

gquintard requested review from Kaliumhexacyanoferrat and MDA2AV as code owners August 27, 2026 21:42

gquintard mentioned this pull request Aug 27, 2026

varnish: set thread_stats_rate=1000 #1351

Draft

2 tasks

Benchmark results: varnish [skip ci]

34c7563

gquintard marked this pull request as draft August 28, 2026 05:10

Merge branch 'main' into varnish-thread-tuning

01193b6

Benchmark results: varnish [skip ci]

c615ea9

gquintard closed this Sep 1, 2026

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varnish: remove thread pool overrides, use built-in defaults - #1350

varnish: remove thread pool overrides, use built-in defaults#1350
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