perf: try to re-use timer when possible

[ronag]

No description provided.

[ronag]

root@467caf9088f0:/undici# node benchmarks/index.js 
http - no agent  x 3,824 ops/sec ±6.06% (75 runs sampled)
http - keepalive x 733 ops/sec ±1.18% (78 runs sampled)
http - keepalive - multiple sockets x 5,001 ops/sec ±1.05% (80 runs sampled)
undici - pipeline x 5,420 ops/sec ±3.56% (78 runs sampled)
undici - request x 6,117 ops/sec ±1.62% (83 runs sampled)
undici - pool - request - multiple sockets x 6,111 ops/sec ±1.09% (81 runs sampled)
undici - stream x 6,514 ops/sec ±1.42% (80 runs sampled)
undici - dispatch x 6,871 ops/sec ±0.71% (84 runs sampled)
undici - noop x 7,001 ops/sec ±0.69% (83 runs sampled)
root@467caf9088f0:/undici# git checkout reuse-timers
Branch reuse-timers set up to track remote branch reuse-timers from origin.
Switched to a new branch 'reuse-timers'
root@467caf9088f0:/undici# node benchmarks/index.js 
http - no agent  x 4,047 ops/sec ±4.75% (80 runs sampled)
http - keepalive x 757 ops/sec ±0.81% (77 runs sampled)
http - keepalive - multiple sockets x 4,952 ops/sec ±0.83% (83 runs sampled)
undici - pipeline x 5,605 ops/sec ±2.56% (81 runs sampled)
undici - request x 6,178 ops/sec ±1.46% (81 runs sampled)
undici - pool - request - multiple sockets x 6,138 ops/sec ±1.07% (82 runs sampled)
undici - stream x 6,500 ops/sec ±0.93% (83 runs sampled)
undici - dispatch x 6,894 ops/sec ±0.72% (82 runs sampled)
undici - noop x 7,038 ops/sec ±0.57% (83 runs sampled)
root@467caf9088f0:/undici# 

[codecov-io]

Codecov Report

Merging #729 (241be32) into main (f6f229b) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##              main      #729   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           24        24           
  Lines         1874      1886   +12     
=========================================
+ Hits          1874      1886   +12     

Impacted Files	Coverage Δ
lib/core/symbols.js	100.00% <ø> (ø)
lib/client.js	100.00% <100.00%> (ø)

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[ronag]

Interestingly enough the perf gain is negligable. Even though clinic flame blames setTimeout.

Not quite sure how think about this. @mcollina wdyt?

[mcollina]

lgtm

[mcollina]

How does the before/after flamegraph look like?

[ronag]

How does the before/after flamegraph look like?

What's the best way to share that?

[mcollina]

zip them and attach them to the issue

[ronag]

Posting clinic data soon. But now I think this PR makes sense regardless whether it improves perf or not.

[ronag]

Archive.zip

70439 main
68510 pr

@mcollina