fix: cap mysql connection pool

configs/workbench.local.json

@@ -1,7 +1,9 @@
 {
   "listen": ":6061",
   "mysql": {
-    "dsn": "root:root@tcp(127.0.0.1:3306)/meeting_im?parseTime=true&charset=utf8mb4,utf8&loc=Local"
+    "dsn": "root:root@tcp(127.0.0.1:3306)/meeting_im?parseTime=true&charset=utf8mb4,utf8&loc=Local",
+    "max_open_conns": 15,
+    "max_idle_conns": 5
   },
   "redis": {
     "addr": "127.0.0.1:6379",

internal/config/config.go

@@ -24,7 +24,9 @@ type Config struct {
 }
 
 type MySQLConfig struct {
-	DSN string `json:"dsn"`
+	DSN          string `json:"dsn"`
+	MaxOpenConns int    `json:"max_open_conns"`
+	MaxIdleConns int    `json:"max_idle_conns"`
 }
 
 type RedisConfig struct {
@@ -90,7 +92,9 @@ func defaultConfig() *Config {
 	return &Config{
 		Listen: ":6061",
 		MySQL: MySQLConfig{
-			DSN: "root:root@tcp(127.0.0.1:3306)/meeting_im?parseTime=true&charset=utf8mb4,utf8&loc=Local",
+			DSN:          "root:root@tcp(127.0.0.1:3306)/meeting_im?parseTime=true&charset=utf8mb4,utf8&loc=Local",
+			MaxOpenConns: 15,
+			MaxIdleConns: 5,
 		},
 		Redis: RedisConfig{
 			Addr:      "127.0.0.1:6379",
@@ -120,6 +124,8 @@ func defaultConfig() *Config {
 func applyEnv(cfg *Config) {
 	setString(&cfg.Listen, "IM_WORKBENCH_LISTEN")
 	setString(&cfg.MySQL.DSN, "IM_WORKBENCH_MYSQL_DSN")
+	setInt(&cfg.MySQL.MaxOpenConns, "IM_WORKBENCH_MYSQL_MAX_OPEN_CONNS")
+	setInt(&cfg.MySQL.MaxIdleConns, "IM_WORKBENCH_MYSQL_MAX_IDLE_CONNS")
 	setString(&cfg.Redis.Addr, "IM_WORKBENCH_REDIS_ADDR")
 	setString(&cfg.Redis.Username, "IM_WORKBENCH_REDIS_USERNAME")
 	setString(&cfg.Redis.Password, "IM_WORKBENCH_REDIS_PASSWORD")
@@ -214,6 +220,14 @@ func setString(target *string, key string) {
 	}
 }
 
+func setInt(target *int, key string) {
+	if value := strings.TrimSpace(os.Getenv(key)); value != "" {
+		if parsed, err := strconv.Atoi(value); err == nil {
+			*target = parsed
+		}
+	}
+}
+
 func setBool(target *bool, key string) {
 	switch strings.ToLower(strings.TrimSpace(os.Getenv(key))) {
 	case "1", "true", "yes", "on":

internal/config/config_test.go

@@ -23,4 +23,19 @@ func TestDefaultConfigUsesMeetingIMDatabase(t *testing.T) {
 	if !strings.Contains(cfg.MySQL.DSN, "/meeting_im?") {
 		t.Fatalf("default mysql dsn = %q, want meeting_im database", cfg.MySQL.DSN)
 	}
+	if cfg.MySQL.MaxOpenConns != 15 || cfg.MySQL.MaxIdleConns != 5 {
+		t.Fatalf("default mysql pool = %d/%d, want 15/5", cfg.MySQL.MaxOpenConns, cfg.MySQL.MaxIdleConns)
+	}
+}
+
+func TestApplyEnvOverridesMySQLPool(t *testing.T) {
+	t.Setenv("IM_WORKBENCH_MYSQL_MAX_OPEN_CONNS", "12")
+	t.Setenv("IM_WORKBENCH_MYSQL_MAX_IDLE_CONNS", "4")
+	cfg := defaultConfig()
+
+	applyEnv(cfg)
+
+	if cfg.MySQL.MaxOpenConns != 12 || cfg.MySQL.MaxIdleConns != 4 {
+		t.Fatalf("mysql pool = %d/%d, want 12/4", cfg.MySQL.MaxOpenConns, cfg.MySQL.MaxIdleConns)
+	}
 }

internal/store/mysql.go

@@ -58,7 +58,7 @@ func SetUIDKey(encoded string) error {
 }
 
 func Open(cfg config.MySQLConfig) (*Store, error) {
-	st, err := openDSN(cfg.DSN)
+	st, err := openDSN(cfg)
 	if err != nil {
 		return nil, err
 	}
@@ -66,13 +66,13 @@ func Open(cfg config.MySQLConfig) (*Store, error) {
 	return st, nil
 }
 
-func openDSN(dsn string) (*Store, error) {
-	db, err := sqlx.Open("mysql", dsn)
+func openDSN(cfg config.MySQLConfig) (*Store, error) {
+	db, err := sqlx.Open("mysql", cfg.DSN)
 	if err != nil {
 		return nil, err
 	}
-	db.SetMaxOpenConns(30)
-	db.SetMaxIdleConns(10)
+	db.SetMaxOpenConns(cfg.MaxOpenConns)
+	db.SetMaxIdleConns(cfg.MaxIdleConns)
 	db.SetConnMaxLifetime(30 * time.Minute)
 	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
 	defer cancel()
@@ -80,7 +80,7 @@ func openDSN(dsn string) (*Store, error) {
 		_ = db.Close()
 		return nil, err
 	}
-	return &Store{db: db, dsn: dsn}, nil
+	return &Store{db: db, dsn: cfg.DSN}, nil
 }
 
 func (s *Store) tenant() int64 {