1
我写了下面的ETL工具，它从MySQL中获取数据，转换成JSON &打印在屏幕调试坚持走程序
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:[email protected](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
}
现在开始，这工作正常，测试数据库，但在生产数据库，在那里有数百万行，在获取1,000行后卡住&停止在屏幕上打印。我让它跑了一晚。
在早晨， 我把它QUIT信号&得到了下面的堆栈跟踪
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
而且，我试图通过注释掉defer rows.Close()调用进一步调试它。现在经过1000行左右，而不是拖延，它会立即返回以下错误：
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
问题：
- 它为什么会得到立即取1000（appox）行后卡住？
- 如何评论出
defer rows.Close()停止卡住&立即恐慌？ - 有没有更好的方法来编写这个程序？
最后，我很抱歉，如果上述任何这些都是愚蠢的问题或问题太长。我是新手，想去学。
第二个错误似乎是因为数据库中的菜单项没有第六个''''-separated元素，所以'itemParts [5]'失败。您可以在使用硬编码索引访问它之前检查'itemParts'的长度。不知道悬挂。 – twotwotwo
'rows.Close（）'中的挂起看起来有点像[这个MySQL驱动程序错误]（https://github.com/go-sql-driver/mysql/issues/285），但我不确定。 – twotwotwo