Concurrent reading from cell is not supported?

[listen-lavender]

Description

Steps to reproduce the issue:

1. an Excel file with many picture cell
2. need concurrent reading from cell
3. check by go run -race

Test Excel
test_import_goods.xlsx

Test Code

package main

import (
  "strconv"
  "sync"

  "github.com/360EntSecGroup-Skylar/excelize/v2"
)

var tableIndex = map[int]string{
  1: "A", 2: "B", 3: "C", 4: "D", 5: "E",
  6: "F", 7: "G", 8: "H", 9: "I", 10: "J",
  11: "K", 12: "L", 13: "M", 14: "N", 15: "O",
  16: "P", 17: "Q", 18: "R", 19: "S", 20: "T",
  21: "U", 22: "V", 23: "W", 24: "X", 25: "Y", 26: "Z",
}

// 检查导入文件
func main() {
  localFile := "test_import_goods.xlsx"
  f, err := excelize.OpenFile(localFile)
  if err != nil {
    println("UploadGoods", "excelize open error", err.Error())
    return
  }

  var (
    sheet string
  )

  sheets := f.GetSheetList()
  if len(sheets) > 0 {
    sheet = sheets[0]
  } else {
    println("UploadGoods", "no sheet")
    return
  }

  var wg sync.WaitGroup

  sheetRows := getSheetRows(f, sheet) //行数量
  sheetCols := getSheetCols(f, sheet) //列数量

  // time.Sleep(time.Second * 3600)
  for i := 0; i < sheetRows; i++ {
    if i < 2 {
      continue
    }
    for j := 0; j < sheetCols; j++ {
      if j < 9 {
        continue
      }
      wg.Add(1)
      go func(i int, j int) {
        defer func() {
          if r := recover(); r != nil {
            println("ImportCheckImpl error")
          }
        }()
        defer wg.Done()
        if _, _, err := f.GetPicture(sheet, tableIndex[j+1]+strconv.Itoa(i+1)); err != nil {
          println("GetPicture", err.Error())
        }
      }(i, j)
    }
  }
  wg.Wait()
}

//读取行数
func getSheetRows(f *excelize.File, sheet string) int {
  i := 0
  rows, err := f.Rows(sheet)
  if err != nil {
    println("getSheetCols f.Rows", "excelize open error", err.Error())
    return i
  }
  for rows.Next() {
    //读取每行的数据
    cols, err := rows.Columns()
    if err != nil {
      println("getSheetCols rows.Columns()", "row", i, "get columns error", err.Error())
      continue
    }
    cData := ""
    for _, c := range cols {
      cData = cData + c
    }
    if cData == "" { //判断下一行是否为空数据(存在表格显示没有数据但是能读取出空数据的情况)
      break
    }
    i = i + 1
    continue
  }
  return i
}

//读取列数
func getSheetCols(f *excelize.File, sheet string) int {
  i := 0
  cols, err := f.Cols(sheet)
  if err != nil {
    println("getSheetCols f.Rows", "excelize open error", err.Error())
    return i
  }
  for cols.Next() {
    //读取每行的数据
    // cols, err := rcols.Columns()
    cols, err := cols.Rows()
    if err != nil {
      println("getSheetCols rows.Columns()", "row", i, "get columns error", err.Error())
      continue
    }
    cData := ""
    for _, c := range cols {
      cData = cData + c
    }
    if cData == "" { //判断下一行是否为空数据(存在表格显示没有数据但是能读取出空数据的情况)
      break
    }
    i = i + 1
    continue
  }
  return i
}

Describe the results you received:

Describe the results you expected:

Output of go version:

go version go1.14.4 darwin/amd64

Excelize version or commit ID:

excelize/v2@v2.3.1

Output of Error message:

==================
WARNING: DATA RACE
Write at 0x00c000519b90 by goroutine 28:
  runtime.mapassign_faststr()
      /usr/local/Cellar/go/1.14/src/runtime/map_faststr.go:202 +0x0
  github.com/360EntSecGroup-Skylar/excelize/v2.(*File).drawingParser()
      /usr/local/Cellar/go/1.14/selfcode/pkg/mod/github.com/360!ent!sec!group-!skylar/excelize/v2@v2.3.1/drawing.go:1165 +0xcf2
  github.com/360EntSecGroup-Skylar/excelize/v2.(*File).getPicture()
      /usr/local/Cellar/go/1.14/selfcode/pkg/mod/github.com/360!ent!sec!group-!skylar/excelize/v2@v2.3.1/picture.go:513 +0x6d
  github.com/360EntSecGroup-Skylar/excelize/v2.(*File).GetPicture()
      /usr/local/Cellar/go/1.14/selfcode/pkg/mod/github.com/360!ent!sec!group-!skylar/excelize/v2@v2.3.1/picture.go:478 +0x35b
  main.main.func1()
      /Users/lavenderuni/workspace/yunzujia/go/src/code.clouderwork.com/clouderwork/ycd_goods/test/test_import_goods.go:154 +0x20c

Previous read at 0x00c000519b90 by goroutine 29:
  runtime.mapaccess1_faststr()
      /usr/local/Cellar/go/1.14/src/runtime/map_faststr.go:12 +0x0
  github.com/360EntSecGroup-Skylar/excelize/v2.(*File).drawingParser()
      /usr/local/Cellar/go/1.14/selfcode/pkg/mod/github.com/360!ent!sec!group-!skylar/excelize/v2@v2.3.1/drawing.go:1141 +0x9c
  github.com/360EntSecGroup-Skylar/excelize/v2.(*File).getPicture()
      /usr/local/Cellar/go/1.14/selfcode/pkg/mod/github.com/360!ent!sec!group-!skylar/excelize/v2@v2.3.1/picture.go:513 +0x6d
  github.com/360EntSecGroup-Skylar/excelize/v2.(*File).GetPicture()
      /usr/local/Cellar/go/1.14/selfcode/pkg/mod/github.com/360!ent!sec!group-!skylar/excelize/v2@v2.3.1/picture.go:478 +0x35b
  main.main.func1()
      /Users/lavenderuni/workspace/yunzujia/go/src/code.clouderwork.com/clouderwork/ycd_goods/test/test_import_goods.go:154 +0x20c

Goroutine 28 (running) created at:
  main.main()
      /Users/lavenderuni/workspace/yunzujia/go/src/code.clouderwork.com/clouderwork/ycd_goods/test/test_import_goods.go:144 +0xa51

Goroutine 29 (running) created at:
  main.main()
      /Users/lavenderuni/workspace/yunzujia/go/src/code.clouderwork.com/clouderwork/ycd_goods/test/test_import_goods.go:144 +0xa51
==================
==================
WARNING: DATA RACE
Read at 0x00c000a10340 by goroutine 31:
  github.com/360EntSecGroup-Skylar/excelize/v2.(*File).getSheetRelationshipsTargetByID()
      /usr/local/Cellar/go/1.14/selfcode/pkg/mod/github.com/360!ent!sec!group-!skylar/excelize/v2@v2.3.1/picture.go:429 +0x20b
  github.com/360EntSecGroup-Skylar/excelize/v2.(*File).GetPicture()
      /usr/local/Cellar/go/1.14/selfcode/pkg/mod/github.com/360!ent!sec!group-!skylar/excelize/v2@v2.3.1/picture.go:469 +0x191
  main.main.func1()
      /Users/lavenderuni/workspace/yunzujia/go/src/code.clouderwork.com/clouderwork/ycd_goods/test/test_import_goods.go:154 +0x20c

Previous write at 0x00c000a10340 by goroutine 28:
  reflect.typedmemmove()
      /usr/local/Cellar/go/1.14/src/runtime/mbarrier.go:177 +0x0
  reflect.Value.Set()
      /usr/local/Cellar/go/1.14/src/reflect/value.go:1534 +0xfb
  reflect.Append()
      /usr/local/Cellar/go/1.14/src/reflect/value.go:2028 +0x151
  encoding/xml.(*Decoder).unmarshal()
      /usr/local/Cellar/go/1.14/src/encoding/xml/read.go:398 +0x3552
  encoding/xml.(*Decoder).unmarshalPath()
      /usr/local/Cellar/go/1.14/src/encoding/xml/read.go:690 +0x90c
  encoding/xml.(*Decoder).unmarshal()
      /usr/local/Cellar/go/1.14/src/encoding/xml/read.go:524 +0x16a7
  encoding/xml.(*Decoder).DecodeElement()
      /usr/local/Cellar/go/1.14/src/encoding/xml/read.go:151 +0x11e
  encoding/xml.(*Decoder).Decode()
      /usr/local/Cellar/go/1.14/src/encoding/xml/read.go:139 +0x438
  github.com/360EntSecGroup-Skylar/excelize/v2.(*File).relsReader()
      /usr/local/Cellar/go/1.14/selfcode/pkg/mod/github.com/360!ent!sec!group-!skylar/excelize/v2@v2.3.1/sheet.go:1617 +0x44d
  github.com/360EntSecGroup-Skylar/excelize/v2.(*File).getSheetRelationshipsTargetByID()
      /usr/local/Cellar/go/1.14/selfcode/pkg/mod/github.com/360!ent!sec!group-!skylar/excelize/v2@v2.3.1/picture.go:425 +0x19e
  github.com/360EntSecGroup-Skylar/excelize/v2.(*File).GetPicture()
      /usr/local/Cellar/go/1.14/selfcode/pkg/mod/github.com/360!ent!sec!group-!skylar/excelize/v2@v2.3.1/picture.go:469 +0x191
  main.main.func1()
      /Users/lavenderuni/workspace/yunzujia/go/src/code.clouderwork.com/clouderwork/ycd_goods/test/test_import_goods.go:154 +0x20c

Goroutine 31 (running) created at:
  main.main()
      /Users/lavenderuni/workspace/yunzujia/go/src/code.clouderwork.com/clouderwork/ycd_goods/test/test_import_goods.go:144 +0xa51

Goroutine 28 (running) created at:
  main.main()
      /Users/lavenderuni/workspace/yunzujia/go/src/code.clouderwork.com/clouderwork/ycd_goods/test/test_import_goods.go:144 +0xa51
==================
==================
WARNING: DATA RACE
Read at 0x00c00071e178 by goroutine 89:
  github.com/360EntSecGroup-Skylar/excelize/v2.(*File).drawingParser()
      /usr/local/Cellar/go/1.14/selfcode/pkg/mod/github.com/360!ent!sec!group-!skylar/excelize/v2@v2.3.1/drawing.go:1168 +0xdae
  github.com/360EntSecGroup-Skylar/excelize/v2.(*File).getPicture()
      /usr/local/Cellar/go/1.14/selfcode/pkg/mod/github.com/360!ent!sec!group-!skylar/excelize/v2@v2.3.1/picture.go:513 +0x6d
  github.com/360EntSecGroup-Skylar/excelize/v2.(*File).GetPicture()
      /usr/local/Cellar/go/1.14/selfcode/pkg/mod/github.com/360!ent!sec!group-!skylar/excelize/v2@v2.3.1/picture.go:478 +0x35b
  main.main.func1()
      /Users/lavenderuni/workspace/yunzujia/go/src/code.clouderwork.com/clouderwork/ycd_goods/test/test_import_goods.go:154 +0x20c

Previous write at 0x00c00071e178 by goroutine 33:
  [failed to restore the stack]

Goroutine 89 (running) created at:
  main.main()
      /Users/lavenderuni/workspace/yunzujia/go/src/code.clouderwork.com/clouderwork/ycd_goods/test/test_import_goods.go:144 +0xa51

Goroutine 33 (running) created at:
  main.main()
      /Users/lavenderuni/workspace/yunzujia/go/src/code.clouderwork.com/clouderwork/ycd_goods/test/test_import_goods.go:144 +0xa51
==================

Environment details (OS, Microsoft Excel™ version, physical, etc.):

[xuri]

Thanks for your issue, currently, this library doesn't support reading data concurrently.

[listen-lavender]

@xuri is it possible to be supported? is it be supported on the way?

[listen-lavender]

@xuri I want to fork a private repository for the concurrent reading feature. And if i can ignore writing scenario, is it easy to realize my goal? can you help me with any good prompt?

[xuri]

Use sync.Map instead of the map in the File struct and make all struct reader concurrency safe.

[listen-lavender]

@xuri many thanks

[listen-lavender]

@xuri Okay, my concurrent reading problem is solved by this issue. I wonder if it is easy to support concurrent writing. If use sync.Map instead of the unsafe map, then concurrent writing can be realized. I would like to contribute this project with a pull request in my spare time.

And this is my temporary solution for concurrent reading.

package excelize

import "sync"

const (
	real_delete = false
)

type RWMapRelationships struct {
	relationships map[string]*xlsxRelationships
	rwl           sync.RWMutex
}

func NewRWMapRelationships() *RWMapRelationships {
	return &RWMapRelationships{
		relationships: make(map[string]*xlsxRelationships),
	}
}

func (rwmap *RWMapRelationships) GetSet(key string, extract func(string) *xlsxRelationships) *xlsxRelationships {
	rwmap.rwl.RLock()
	val := rwmap.relationships[key]
	rwmap.rwl.RUnlock()
	if val != nil {
		return val
	}
	rwmap.rwl.Lock()
	val = rwmap.relationships[key]
	if val == nil {
		if extract != nil {
			val = extract(key)
			rwmap.relationships[key] = val
		}
	}
	rwmap.rwl.Unlock()
	return val
}

func (rwmap *RWMapRelationships) Get(key string) *xlsxRelationships {
	rwmap.rwl.RLock()
	val := rwmap.relationships[key]
	rwmap.rwl.RUnlock()
	return val
}

func (rwmap *RWMapRelationships) Set(key string, val *xlsxRelationships) {
	rwmap.rwl.Lock()
	rwmap.relationships[key] = val
	rwmap.rwl.Unlock()
}

func (rwmap *RWMapRelationships) Delete(key string) {
	rwmap.rwl.Lock()
	if !real_delete {
		rwmap.relationships[key] = nil
	} else {
		delete(rwmap.relationships, key)
	}
	rwmap.rwl.Unlock()
}

func (rwmap *RWMapRelationships) Shadow() map[string]*xlsxRelationships {
	rwmap.rwl.RLock()
	s := make(map[string]*xlsxRelationships, len(rwmap.relationships))
	for key, val := range rwmap.relationships {
		s[key] = val
	}
	rwmap.rwl.RUnlock()
	return s
}

type RWMapDrawings struct {
	drawings map[string]*xlsxWsDr
	rwl      sync.RWMutex
}

func NewRWMapDrawings() *RWMapDrawings {
	return &RWMapDrawings{
		drawings: make(map[string]*xlsxWsDr),
	}
}

func (rwmap *RWMapDrawings) GetSet(key string, extract func(string) *xlsxWsDr) *xlsxWsDr {
	rwmap.rwl.RLock()
	val := rwmap.drawings[key]
	rwmap.rwl.RUnlock()
	if val != nil {
		return val
	}
	rwmap.rwl.Lock()
	val = rwmap.drawings[key]
	if val == nil {
		if extract != nil {
			val = extract(key)
			rwmap.drawings[key] = val
		}
	}
	rwmap.rwl.Unlock()
	return val
}

func (rwmap *RWMapDrawings) Get(key string) *xlsxWsDr {
	rwmap.rwl.RLock()
	val := rwmap.drawings[key]
	rwmap.rwl.RUnlock()
	return val
}

func (rwmap *RWMapDrawings) Set(key string, val *xlsxWsDr) {
	rwmap.rwl.Lock()
	rwmap.drawings[key] = val
	rwmap.rwl.Unlock()
}

func (rwmap *RWMapDrawings) Delete(key string) {
	rwmap.rwl.Lock()
	if !real_delete {
		rwmap.drawings[key] = nil
	} else {
		delete(rwmap.drawings, key)
	}
	rwmap.rwl.Unlock()
}

func (rwmap *RWMapDrawings) Shadow() map[string]*xlsxWsDr {
	rwmap.rwl.RLock()
	s := make(map[string]*xlsxWsDr, len(rwmap.drawings))
	for key, val := range rwmap.drawings {
		s[key] = val
	}
	rwmap.rwl.RUnlock()
	return s
}

[xuri]

I have added concurrency get cell picture support, please try to upgrade the master branch code, and this feature will be released in the next version.