perf(recovery): optimize line reading in stack function

[1911860538]

Optimize stack function to avoid reading entire files when generating stack traces

• Introduce readNthLine function that reads only the specified line from a file
• Significantly improve performance based on micro-benchmarks:
  • ~33% faster execution (115,994 ns/op → 78,139 ns/op)
  • ~94% reduction in memory usage (178,962 B/op → 10,526 B/op)
  • ~47% increase in throughput (10,278 → 15,106 iterations)
  • ~7% reduction in allocations (30 → 28 allocs/op)
• Demonstrate real-world improvements with hey tool (100,000 panic requests, 100 concurrent connections):
  • ~31% faster total execution time (25.44s → 17.51s)
  • ~45% increase in requests/sec (3,930 → 5,711)
  • ~31% faster average response time (0.0247s → 0.0170s)
  • Improved latency distribution across all percentiles
• Improves efficiency by minimizing I/O operations, especially for large source files
• Maintains the same functionality while reducing resource consumption

[1911860538]

Below is stack benchmark comparison:

Before

goos: darwin
goarch: amd64
pkg: github.com/gin-gonic/gin
cpu: Intel(R) Core(TM) i7-8569U CPU @ 2.80GHz
BenchmarkStack
BenchmarkStack-8   	   10278	    115994 ns/op	  178962 B/op	      30 allocs/op
PASS

Process finished with the exit code 0

After

goos: darwin
goarch: amd64
pkg: github.com/gin-gonic/gin
cpu: Intel(R) Core(TM) i7-8569U CPU @ 2.80GHz
BenchmarkStack
BenchmarkStack-8   	   15106	     78139 ns/op	   10526 B/op	      28 allocs/op
PASS

Process finished with the exit code 0

[1911860538]

hey load test

recovery test code

package main

import (
	"log"
	"net/http"

	"github.com/gin-gonic/gin"
)

func main() {
	gin.SetMode(gin.ReleaseMode)

	r := gin.New()

	r.Use(gin.CustomRecoveryWithWriter(gin.DefaultErrorWriter, func(c *gin.Context, err any) {
		c.JSON(http.StatusInternalServerError, gin.H{
			"message": "internal error",
		})
	}))

	r.GET("/panic", func(c *gin.Context) {
		panic("trigger panic")
	})

	err := r.Run(":8080")
	if err != nil {
		log.Fatal(err)
	}
}

hey command

hey -n 100000 -c 100 http://localhost:8080/panic

benchmark results before optimization using hey

hey -n 100000 -c 100 http://localhost:8080/panic

Summary:
  Total:        25.4435 secs
  Slowest:      0.3380 secs
  Fastest:      0.0006 secs
  Average:      0.0247 secs
  Requests/sec: 3930.2828
  
  Total data:   2800000 bytes
  Size/request: 28 bytes

Response time histogram:
  0.001 [1]     |
  0.034 [70813] |■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
  0.068 [19266] |■■■■■■■■■■■
  0.102 [6610]  |■■■■
  0.136 [2197]  |■
  0.169 [747]   |
  0.203 [252]   |
  0.237 [75]    |
  0.271 [26]    |
  0.304 [8]     |
  0.338 [5]     |


Latency distribution:
  10% in 0.0013 secs
  25% in 0.0025 secs
  50% in 0.0063 secs
  75% in 0.0375 secs
  90% in 0.0678 secs
  95% in 0.0901 secs
  99% in 0.1391 secs

Details (average, fastest, slowest):
  DNS+dialup:   0.0000 secs, 0.0006 secs, 0.3380 secs
  DNS-lookup:   0.0000 secs, 0.0000 secs, 0.0087 secs
  req write:    0.0000 secs, 0.0000 secs, 0.0049 secs
  resp wait:    0.0246 secs, 0.0005 secs, 0.3380 secs
  resp read:    0.0000 secs, 0.0000 secs, 0.0101 secs

Status code distribution:
  [500] 100000 responses

benchmark results after optimization using hey

hey -n 100000 -c 100 http://localhost:8080/panic

Summary:
  Total:        17.5100 secs
  Slowest:      0.3669 secs
  Fastest:      0.0004 secs
  Average:      0.0170 secs
  Requests/sec: 5711.0322
  
  Total data:   2800000 bytes
  Size/request: 28 bytes

Response time histogram:
  0.000 [1]     |
  0.037 [81980] |■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
  0.074 [12141] |■■■■■■
  0.110 [3550]  |■■
  0.147 [1593]  |■
  0.184 [481]   |
  0.220 [172]   |
  0.257 [53]    |
  0.294 [20]    |
  0.330 [4]     |
  0.367 [5]     |


Latency distribution:
  10% in 0.0010 secs
  25% in 0.0017 secs
  50% in 0.0036 secs
  75% in 0.0091 secs
  90% in 0.0610 secs
  95% in 0.0795 secs
  99% in 0.1377 secs

Details (average, fastest, slowest):
  DNS+dialup:   0.0000 secs, 0.0004 secs, 0.3669 secs
  DNS-lookup:   0.0000 secs, 0.0000 secs, 0.0080 secs
  req write:    0.0000 secs, 0.0000 secs, 0.0056 secs
  resp wait:    0.0169 secs, 0.0004 secs, 0.3669 secs
  resp read:    0.0000 secs, 0.0000 secs, 0.0196 secs

Status code distribution:
  [500] 100000 responses

[codecov]

Codecov Report

❌ Patch coverage is 95.23810% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 98.92%. Comparing base (3dc1cd6) to head (1226362).
⚠️ Report is 225 commits behind head on master.

Files with missing lines	Patch %	Lines
recovery.go	95.23%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4466      +/-   ##
==========================================
- Coverage   99.21%   98.92%   -0.29%     
==========================================
  Files          42       44       +2     
  Lines        3182     2986     -196     
==========================================
- Hits         3157     2954     -203     
- Misses         17       20       +3     
- Partials        8       12       +4     

Flag	Coverage Δ
	?
--ldflags="-checklinkname=0" -tags sonic	98.85% <95.23%> (?)
-tags go_json	98.78% <95.23%> (?)
-tags nomsgpack	98.84% <95.23%> (?)
go-1.18	?
go-1.19	?
go-1.20	?
go-1.21	?
go-1.24	98.86% <95.23%> (?)
go-1.25	98.92% <95.23%> (?)
macos-latest	98.92% <95.23%> (-0.29%)	⬇️
ubuntu-latest	98.86% <95.23%> (-0.36%)	⬇️

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[1911860538]

Refs:

• perf(recover): replace bytes with strings in function for better performance #4252
• perf(recovery): optimize the log output of CustomRecoveryWithWriter #4258

[1911860538]

@appleboy Please help to review this.