求大神runtime error: invalid memory address or nil pointer dereference

database/sql.(Stmt).Exec(0x0, 0x0, 0x0, 0x0, 0x7efe6b4862a8, 0xc4201ce600, 0x0, 0xc42017e555) /usr/local/go/src/database/sql/sql.go:2253 +0x65 main.mpp(0x7a7fe0, 0xc4203421c0, 0xc420332500) /root/golang_mysql_proxy_pool/pool.go:151 +0x12e1 stmt, _ := dbx.Prepare(query) res, _ := stmt.Exec() `dbx.Prepare(query)`返回的error要检查下，不要忽略函数返回的error，哪怕你认为这个error不可能发生

空指针 但不知道在哪里 贴代码 

package main import ( "database/sql" "fmt" _ "github.com/go-sql-driver/mysql" _ "github.com/lib/pq" _ "github.com/ziutek/mymysql/godrv" "log" "net/http" // "strings" "encoding/json" // "os" "regexp" "runtime" "strconv" "time" ) // /** var config = readConfig() // fmt.Println(config) // var max_pool = strconv.ParseInt(string(config["max_pool_size"]), 10, 0) // **/ var MAX_POOL_SIZE = 10 var MySQLPool chan *sql.DB func getPool() *sql.DB { config := readConfig() parallel_num, _ := strconv.ParseInt(config["parallel_num"], 10, 0) runtime.GOMAXPROCS(int(parallel_num)) dbAdapter := config["db_adapter"] dbhost := config["dbhost"] dbport := config["dbport"] dbuser := config["dbuser"] dbpwd := config["dbpwd"] dbname := config["dbname"] // fmt.Println(config) // fmt.Println(config["bind"]) if MySQLPool == nil { MySQLPool = make(chan *sql.DB, MAX_POOL_SIZE) } if len(MySQLPool) == 0 { //if no DB conn, we make the pool max_pool, _ := strconv.ParseInt(config["max_pool_size"], 10, 0) // fmt.Println(max_pool) go func() { for i := 0; i < int(max_pool); i++ { fmt.Println("crean DB conn....") // mysqlc, err := sql.Open("mymysql", "tcp:127.0.0.1:3306*test/root/") if dbAdapter == "mysql" { //mysql conn mysqlc, err := sql.Open("mymysql", "tcp:"+dbhost+":"+dbport+"*"+dbname+"/"+dbuser+"/"+dbpwd) if err != nil { panic(err) } putPool(mysqlc) } else if dbAdapter == "pgsql" { //pgsql conn // mysqlc, err := sql.Open("postgres", "user=postgres_user password=password host=172.16.2.29 dbname=my_postgres_db sslmode=disable") postgrec, err := sql.Open("postgres", "user="+dbuser+" password="+dbpwd+" host="+dbhost+" port="+dbport+" dbname="+dbname+" sslmode=disable") if err != nil { panic(err) } putPool(postgrec) } } }() } return <-MySQLPool //parallel return DB conn use pool } func putPool(conn *sql.DB) { // fmt.Println("crean DB conn....") if MySQLPool == nil { MySQLPool = make(chan *sql.DB, MAX_POOL_SIZE) } if len(MySQLPool) == MAX_POOL_SIZE { conn.Close() return } MySQLPool <- conn } func mpp(w http.ResponseWriter, r *http.Request) { if r.Method == "POST" { /** * the json return back * code 0 is for success * 1 is for wrong query * 2 is for wrong get data * status success or fail * rows query data **/ var back = make(map[string]interface{}) //return json back["code"] = 0 back["status"] = "success" back["rows"] = "" var errCode = 0 uukey := r.FormValue("uukey") if uukey != config["uukey"] { back["code"] = 3 back["status"] = "fail" // log.Fatal("uukey not the same") errCode = 1 } cache := r.FormValue("cache") //cache enable ccKey := r.FormValue("cache_key") //cache key ccTime := r.FormValue("cctime") //cache time if errCode == 0 { //check secure uukey query := r.FormValue("query") fmt.Println("query is: ", query) // os.Exit(3) //get cache info if query == "cc_info" { //get all cache info // ccInfo() cc_info := ccInfo() fmt.Fprintf(w, cc_info) return } else if config["cache"] == "1" && query == "cc_get" { //get cache by key // ccGet(ccKey) fmt.Fprintf(w, ccGet(ccKey)) return } //get DB data dbx := getPool() //get the DB conn from pool when we want to use //regular check sql insert/update/delete querySelect := 1 matchedI, _ := regexp.MatchString("insert.*", query) matchedD, _ := regexp.MatchString("delete.*", query) matchedU, _ := regexp.MatchString("update.*", query) // fmt.Println("regular query: ", matched) //if not select query if matchedI || matchedD || matchedU { // fmt.Println("not select query") stmt, _ := dbx.Prepare(query) res, _ := stmt.Exec() // fmt.Println("res: ", res) // return res.RowsAffected() affect, _ := res.RowsAffected() // fmt.Println("affect: ", affect) back["rows"] = int(affect) // back["rows"] = 1 querySelect = 0 // return } else { // var rows interface{} // rows, errQuery := dbx.Query(query) rows, errQuery := dbx.Query(query) // rows, affRows, errQuery := dbx.Query(query) // fmt.Println("rows: ", rows) // fmt.Println("affRows: ", affRows) // fmt.Println("affRows: ", rows.RowsAffected()) if errQuery != nil { back["code"] = 1 back["status"] = "fail" // log.Fatal(err) fmt.Println(errQuery) errCode = 1 } if errQuery == nil { // var email string colNames, err := rows.Columns() checkErr(err) readCols := make([]interface{}, len(colNames)) writeCols := make([][]byte, len(colNames)) // writeCols := make([]byte, len(colNames)) // writeCols := make([]interface{}, len(colNames)) for i, _ := range writeCols { readCols[i] = &writeCols[i] } result := make([]map[string]interface{}, 0) // fmt.Println("len res:", len(result)) // fmt.Println(result) // fmt.Println(colNames) for rows.Next() { if err := rows.Scan(readCols...); err != nil { log.Fatal(err) back["code"] = 2 back["status"] = "fail" } // fmt.Println(writeCols) var tmpStr string tmpMap := make(map[string]interface{}) for i, raw := range writeCols { // var tmpStr string if raw == nil { // result[i] = "\\N" } else { tmpStr += string(raw) tmpMap[colNames[i]] = string(raw) } } result = append(result, tmpMap) } if err := rows.Err(); err != nil { log.Fatal(err) } // fmt.Println(result) // back["rows"] = resStr back["rows"] = result } // defer putPool(dbx) //put the DB conn into pool after finish used } defer putPool(dbx) //put the DB conn into pool after finish used //just query DB jsback, _ := json.Marshal(back) //if set cache if string(config["cache"]) == "1" && cache == "1" && ccKey != "" && querySelect == 1 { startTime := strconv.FormatInt(time.Now().Unix(), 10) ccJsback := string(jsback) + string(config["cache_split"]) + string(startTime) + ":" + ccTime //store cache // ccSet(ccKey, string(jsback)) ccSet(ccKey, string(ccJsback)) } // jsback, _ := json.Marshal(result) fmt.Fprintf(w, string(jsback)) // defer putPool(dbx) } } }