调试卡住的Go程序

huangapple
go评论78阅读模式
英文:

Debugging stuck go programs

问题

以下是翻译好的内容：

我编写了以下的ETL工具，它从Mysql中获取数据，转换为JSON并在屏幕上打印出来。

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
}

现在，在测试数据库中它工作得很好，但在生产数据库中，当有数百万行数据时，它在获取了大约1,000行数据后就会停止打印在屏幕上。我让它运行了一整晚。

早上，我发送了QUIT信号，并得到了以下的堆栈跟踪：

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

此外，我尝试通过注释掉defer rows.Close()来进一步调试它。现在，在获取了大约1,000行数据后，它不再停止，而是立即返回以下错误：

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：

  1. 为什么在获取了大约1,000行数据后就会立即停止？
  2. 为什么注释掉defer rows.Close()后不再停止，而是立即引发错误？
  3. 有没有更好的方法来编写这个程序？

最后，如果上述问题中有任何愚蠢的问题或问题太长，请原谅。我是Go的新手，正在努力学习。

英文:

I wrote the following ETL tool which gets data from Mysql, convert into JSON & print it on the screen

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
}

Now, This works fine for test database but in production database where there are millions of rows, it gets stuck after fetching 1,000 rows & stops printing on screen. I left it running for the night.

In morning,
I sent it QUIT signal & got the following stack trace

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

Further, I tried debugging it further by commenting out the defer rows.Close() call. now after 1,000 rows or so, instead of stalling, it immediately returns the following error:

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

Questions:

  1. Why does it get stuck immediately after fetching 1,000(appox) rows?
  2. How does commenting out defer rows.Close() stops from getting stuck & panics immediately?
  3. Is there is a better way to write this program?

Lastly, I am sorry if any of the above these are stupid questions or question is too long. I am new to Go & trying to learn.

答案1

得分: 0

这是一个驱动程序的问题。通过移除延迟调用并检查数组边界来修复它。

英文:

This was a issue with the driver. Fixed it by removing the defer call & checking the array bounds.

huangapple
  • 本文由 发表于 2015年9月20日 13:44:19
  • 转载请务必保留本文链接：https://go.coder-hub.com/32676227.html
  • debugging
  • go
  • json
  • mysql
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