調試卡死程序

Question

我編寫了以下ETL工具，該工具從Mysql獲取數據，轉換為JSON並將其打印在屏幕上

package main

import (
    "bytes"
    "database/sql"
    "encoding/json"
    "fmt"
    "log"
    "strconv"
    "strings"
    "time"

    _ "github.com/go-sql-driver/mysql"
)

const dbformat = "2006-01-02 15:04:05"

type MysqlReceipt struct {
    Id               int
    Amount           sql.NullFloat64
    Cc_last4         sql.NullString
    Employee_id      sql.NullString
    Employee_name    sql.NullString
    Is_test          byte
    Menu_items       sql.NullString
    Payable          sql.NullFloat64
    Pos_type         sql.NullString
    Pos_version      sql.NullString
    Punchh_key       string
    Receipt_datetime sql.NullString
    Subtotal_amount  sql.NullFloat64
    Transaction_no   sql.NullString
    Business_id      int
    Location_id      int
    Created_at       string
    Updated_at       sql.NullString
    Revenue_code     sql.NullString
    Revenue_id       sql.NullString
    Status           sql.NullString
    Ipv4_addr        sql.NullString
}

type Menu_item struct {
    id, name, family, major_group, item_type string
    qty                                      int
    amount                                   float64
}

type BigReceipt struct {
    Id                       int
    Amount                   float64
    Cc_last4                 string
    Employee_id              string `json:",omitempty"`
    Employee_name            string `json:",omitempty"`
    Is_test                  byte
    Menu_item_name           string
    Menu_item_id             string
    Menu_item_amount         float64
    Menu_item_family         string
    Menu_item_major_group    string
    Menu_item_type           string
    Menu_item_qty            int
    Payable                  float64
    Pos_type                 string `json:",omitempty"`
    Pos_version              string `json:",omitempty"`
    Punchh_key               string
    Receipt_datetime         string
    Subtotal_amount          float64
    Transaction_no           string `json:",omitempty"`
    Business_id, Location_id int
    Created_at               time.Time
    Updated_at               time.Time `json:",omitempty"`
    Revenue_code             string    `json:",omitempty"`
    Revenue_id               string    `json:",omitempty"`
    Status                   string    `json:",omitempty"`
    Ipv4_addr                string    `json:",omitempty"`
    Stored_at                int64
}

func (m Menu_item) ValidItem() bool {
    if m.item_type == "M" || m.item_type == "D" {
        return true
    } else {
        return false
    }
}

func main() {
    db, err := sql.Open("mysql", "root:password@tcp(xxxxxxx.us-east-1.rds.amazonaws.com:3306)/db_name_goes_here")
    if err != nil {
        log.Fatal(err)
    }
    err = db.Ping()
    if err != nil {
        log.Fatal(err)
    }
    defer db.Close()
    rows, err := db.Query(`select id,amount,cc_last4,employee_id,employee_name,is_test,menu_items,payable,pos_type,
    pos_version,punchh_key,receipt_datetime,subtotal_amount,transaction_no,business_id,location_id,created_at,
    updated_at,revenue_code,revenue_id,status,ipv4_addr from receipts`)
    if err != nil {
        log.Fatal(err)
    }
    defer rows.Close()
    for rows.Next() {
        var mr MysqlReceipt
        err = rows.Scan(&mr.Id, &mr.Amount, &mr.Cc_last4, &mr.Employee_id, &mr.Employee_name, &mr.Is_test, &mr.Menu_items,
            &mr.Payable, &mr.Pos_type, &mr.Pos_version, &mr.Punchh_key, &mr.Receipt_datetime, &mr.Subtotal_amount, &mr.Transaction_no,
            &mr.Business_id, &mr.Location_id, &mr.Created_at, &mr.Updated_at, &mr.Revenue_code, &mr.Revenue_id, &mr.Status, &mr.Ipv4_addr)
        if err != nil {
            log.Fatal(err)
        }
        if !mr.Menu_items.Valid {
            continue
        }
        r := BigReceipt{Id: mr.Id,
            Amount:           mr.Amount.Float64,
            Cc_last4:         mr.Cc_last4.String,
            Employee_id:      mr.Employee_id.String,
            Employee_name:    mr.Employee_name.String,
            Is_test:          mr.Is_test,
            Payable:          mr.Payable.Float64,
            Pos_type:         mr.Pos_type.String,
            Pos_version:      mr.Pos_version.String,
            Punchh_key:       mr.Punchh_key,
            Receipt_datetime: mr.Receipt_datetime.String,
            Subtotal_amount:  mr.Subtotal_amount.Float64,
            Transaction_no:   mr.Transaction_no.String,
            Business_id:      mr.Business_id,
            Location_id:      mr.Location_id,
            Revenue_code:     mr.Revenue_code.String,
            Revenue_id:       mr.Revenue_id.String,
            Status:           mr.Status.String,
            Ipv4_addr:        mr.Ipv4_addr.String,
            Stored_at:        time.Now().Unix(),
        }
        r.Created_at = datetimeParse(mr.Created_at)
        if mr.Updated_at.Valid {
            r.Updated_at = datetimeParse(mr.Updated_at.String)
        }
        menuItems := strings.Split(mr.Menu_items.String, "^")
        items := parseMenuItems(menuItems)
        for _, v := range items {
            r.Menu_item_name = v.name
            r.Menu_item_id = v.id
            r.Menu_item_amount = v.amount
            r.Menu_item_family = v.family
            r.Menu_item_major_group = v.major_group
            r.Menu_item_type = v.item_type
            r.Menu_item_qty = v.qty
            b, err := json.Marshal(r)
            if err != nil {
                log.Fatal(err)
            }
            fmt.Println(r.Id)
            var out bytes.Buffer
            json.Compact(&out, b)
            fmt.Println(string(b))
        }
    }
    err = rows.Err()
    if err != nil {
        log.Fatal(err)
    }
}

func datetimeParse(dateStr string) time.Time {
    datetime, err := time.Parse(dbformat, dateStr)
    if err != nil {
        log.Fatal(err)
    }
    return datetime
}

func parseMenuItems(menuItems []string) []Menu_item {
    var items []Menu_item
    var item Menu_item
    for _, v := range menuItems {
        itemParts := strings.Split(v, "|")

        item.name = itemParts[0]
        item.qty, _ = strconv.Atoi(itemParts[1])
        item.amount, _ = strconv.ParseFloat(itemParts[2], 64)
        item.item_type = strings.ToUpper(itemParts[3])
        item.id = itemParts[4]
        item.family = itemParts[5]
        item.major_group = itemParts[6]
        if item.ValidItem() {
            items = append(items, item)
        } else {
            continue
        }
    }
    return items
}

現在，這對於測試數據庫可以正常工作，但是在具有數百萬行的生產數據庫中，它在獲取1,000行后卡住並停止在屏幕上打印。 我讓它整夜運轉。

早上，我發送了QUIT信號並獲得了以下堆棧跟蹤

SIGQUIT: quit
PC=0x5fecb m=0

goroutine 0 [idle]:
runtime.mach_semaphore_wait(0xe03, 0x0, 0x0, 0x0, 0x0, 0x407520, 0x52db9, 0xffffffffffffffff, 0x0, 0x7fff5fbff0fc, ...)
    /usr/local/Cellar/go/1.5/libexec/src/runtime/sys_darwin_amd64.s:407 +0xb
runtime.semasleep1(0xffffffffffffffff, 0x0)
    /usr/local/Cellar/go/1.5/libexec/src/runtime/os1_darwin.go:385 +0xe5
runtime.semasleep.func1()
    /usr/local/Cellar/go/1.5/libexec/src/runtime/os1_darwin.go:401 +0x29
runtime.systemstack(0x7fff5fbff100)
    /usr/local/Cellar/go/1.5/libexec/src/runtime/asm_amd64.s:278 +0xab
runtime.semasleep(0xffffffffffffffff, 0x0)
    /usr/local/Cellar/go/1.5/libexec/src/runtime/os1_darwin.go:402 +0x36
runtime.notesleep(0x407970)
    /usr/local/Cellar/go/1.5/libexec/src/runtime/lock_sema.go:169 +0x100
runtime.stopm()
    /usr/local/Cellar/go/1.5/libexec/src/runtime/proc1.go:1128 +0x112
runtime.findrunnable(0xc82001d500, 0x0)
    /usr/local/Cellar/go/1.5/libexec/src/runtime/proc1.go:1530 +0x69e
runtime.schedule()
    /usr/local/Cellar/go/1.5/libexec/src/runtime/proc1.go:1639 +0x267
runtime.park_m(0xc820000180)
    /usr/local/Cellar/go/1.5/libexec/src/runtime/proc1.go:1698 +0x18b
runtime.mcall(0x7fff5fbff280)
    /usr/local/Cellar/go/1.5/libexec/src/runtime/asm_amd64.s:204 +0x5b

goroutine 1 [IO wait]:
net.runtime_pollWait(0x7a1000, 0x72, 0xc82000a2d0)
    /usr/local/Cellar/go/1.5/libexec/src/runtime/netpoll.go:157 +0x60
net.(*pollDesc).Wait(0xc8200a4060, 0x72, 0x0, 0x0)
    /usr/local/Cellar/go/1.5/libexec/src/net/fd_poll_runtime.go:73 +0x3a
net.(*pollDesc).WaitRead(0xc8200a4060, 0x0, 0x0)
    /usr/local/Cellar/go/1.5/libexec/src/net/fd_poll_runtime.go:78 +0x36
net.(*netFD).Read(0xc8200a4000, 0xc820372077, 0x3f89, 0x3f89, 0x0, 0x760050, 0xc82000a2d0)
    /usr/local/Cellar/go/1.5/libexec/src/net/fd_unix.go:232 +0x23a
net.(*conn).Read(0xc8200a6000, 0xc820372077, 0x3f89, 0x3f89, 0x0, 0x0, 0x0)
    /usr/local/Cellar/go/1.5/libexec/src/net/net.go:172 +0xe4
github.com/go-sql-driver/mysql.(*buffer).fill(0xc820080080, 0x102, 0x0, 0x0)
    /Users/gaurish/golang/src/github.com/go-sql-driver/mysql/buffer.go:57 +0x2b5
github.com/go-sql-driver/mysql.(*buffer).readNext(0xc820080080, 0x102, 0x0, 0x0, 0x0, 0x0, 0x0)
    /Users/gaurish/golang/src/github.com/go-sql-driver/mysql/buffer.go:86 +0x55
github.com/go-sql-driver/mysql.(*mysqlConn).readPacket(0xc820080080, 0x0, 0x0, 0x0, 0x0, 0x0)
    /Users/gaurish/golang/src/github.com/go-sql-driver/mysql/packets.go:57 +0x47a
github.com/go-sql-driver/mysql.(*mysqlConn).readUntilEOF(0xc820080080, 0x0, 0x0)
    /Users/gaurish/golang/src/github.com/go-sql-driver/mysql/packets.go:698 +0x2d
github.com/go-sql-driver/mysql.(*mysqlRows).Close(0xc8200a0120, 0x0, 0x0)
    /Users/gaurish/golang/src/github.com/go-sql-driver/mysql/rows.go:67 +0x73
database/sql.(*Rows).Close(0xc8200aa060, 0x0, 0x0)
    /usr/local/Cellar/go/1.5/libexec/src/database/sql/sql.go:1710 +0x92
main.parseMenuItems(0xc82036e480, 0x44, 0x44, 0x0, 0x0, 0x0)
    /Users/gaurish/code/practice/mysql2json/mysql2json.go:186 +0x468
main.main()
    /Users/gaurish/code/practice/mysql2json/mysql2json.go:142 +0xf2e

goroutine 17 [syscall, locked to thread]:
runtime.goexit()
    /usr/local/Cellar/go/1.5/libexec/src/runtime/asm_amd64.s:1696 +0x1

goroutine 5 [chan receive]:
database/sql.(*DB).connectionOpener(0xc820088960)
    /usr/local/Cellar/go/1.5/libexec/src/database/sql/sql.go:634 +0x45
created by database/sql.Open
    /usr/local/Cellar/go/1.5/libexec/src/database/sql/sql.go:481 +0x336

rax    0xe
rbx    0xe03
rcx    0x7fff5fbff088
rdx    0x7fff5fbff100
rdi    0xe03
rsi    0x407520
rbp    0x407860
rsp    0x7fff5fbff088
r8     0x407860
r9     0x0
r10    0x0
r11    0x286
r12    0x2c
r13    0x4fc3ed4b8b0
r14    0x14059837c8b46200
r15    0x38
rip    0x5fecb
rflags 0x286
cs     0x7
fs     0x0
gs     0x0
exit status 2

此外，我嘗試通過注釋defer rows.Close()調用來進一步調試它。 現在大約1,000行之后，它不再返回停滯狀態，而是立即返回以下錯誤：

panic: runtime error: index out of range

goroutine 1 [running]:
main.parseMenuItems(0xc820366900, 0x44, 0x44, 0x0, 0x0, 0x0)
    /Users/gaurish/code/practice/mysql2json/mysql2json.go:186 +0x468
main.main()
    /Users/gaurish/code/practice/mysql2json/mysql2json.go:142 +0xf03

goroutine 17 [syscall, locked to thread]:
runtime.goexit()
    /usr/local/Cellar/go/1.5/libexec/src/runtime/asm_amd64.s:1696 +0x1

goroutine 5 [runnable]:
database/sql.(*DB).connectionOpener(0xc820088780)
    /usr/local/Cellar/go/1.5/libexec/src/database/sql/sql.go:634 +0x45
created by database/sql.Open
    /usr/local/Cellar/go/1.5/libexec/src/database/sql/sql.go:481 +0x336
exit status 2

問題：

1. 為什么在獲取1,000（appox）行后立即卡住？
2. 如何注釋掉defer rows.Close()避免立即陷入困境和恐慌？
3. 有沒有更好的方法來編寫此程序？

最后，如果以上任何這些都是愚蠢的問題或問題太長，我感到抱歉。 我是新來的，正在嘗試學習。

Answer 1

這是驅動程序的問題。 通過刪除延遲調用並檢查數組范圍來修復此問題。