Map [String，String]`别名的NotSerializableException [英] NotSerializableException for `Map[String, String]` alias

问题描述

我正在尝试将对象发送给远程角色，但出现了此异常：

I'm trying to send an object to a remote actor and I got this exception:

ERROR akka.remote.EndpointWriter - Transient association error (association remains live)
java.io.NotSerializableException: scala.collection.immutable.MapLike$$anon$2

要序列化的对象是一个case类：

The object being serialized is a case class:

case class LocationReport(idn: String, report: String, timestamp: Option[String], location: Attr, status: Attr, alarms: Attr, network: Attr, sensors: Attr) extends Message(idn) {

  val ts = timestamp getOrElse location("fix_timestamp")

  def json =
    (report ->
      ("TIME" -> ts) ~
      ("location" -> location) ~
      ("alarms" -> alarms) ~
      ("network" -> network) ~
      ("sensors" -> ((status ++ sensors) + ("CUSTOMCLOCK" -> Report.decodeTimestamp(ts)))))
}

而 Attr 是类型r电子定义：

type Attr = Map[String, String]

Message 类非常简单：

abstract class Message(idn: String) {
  def topic = idn
  def json(): JValue
}

我想知道别名/重新定义类型是否会混淆序列化程序。我想我正在使用ProtoBuf序列化，但是在堆栈跟踪中确实看到了 JavaSerializer 。

I'm wondering if the type alias/redefinition is confusing the serializer. I think I'm using ProtoBuf serialization, but I do see JavaSerializer in the stacktrace.

更多调试信息

我新建了一个JavaSerializer，并分别序列化了每个Map。只有一个（警报）无法序列化。这是它们每个的toString：

I newed up a JavaSerializer and individually serialized each of the Maps. Only one (alarms) fails to serialize. Here's the toString of each of them:

此失败：

alarms = Map(LOWBATTERY -> 1373623446000)

这些成功了：

location = Map(a_value -> 6, latitude -> 37.63473, p_value -> 4, longitude -> -97.41459, fix_timestamp -> 3F0AE7FF, status -> OK, fix_type -> MSBL, CUSTOMCLOCK -> 1373644159000)
network = Map(SID -> 1271, RSSI -> 85)
sensors = Map(HUMIDITY -> -999, PRESSURE -> -999, LIGHT -> -999  9:52 AM)
status = Map(TEMPERATURE_F -> 923, CYCLE -> 4, TEMPERATURE1_C -> 335, CAP_REMAINING -> 560, VOLTAGE -> 3691, CAP_FULL -> 3897)

推荐答案

问题是 Map.mapValues 生成了不可序列化的对象。创建警报后，它会通过 alarms.mapValues（hex2Int）之类的内容运行。问题和解决方法在此处描述：

The problem is that Map.mapValues produces an object that's not serializable. When alarms was created, it's run through something like alarms.mapValues(hex2Int). The problem and workaround is described here:

https://issues.scala-lang.org/browse/SI-7005

总之，解决方案是执行 alarms.mapValues（hex2Int）.map（identity）

In short, the solution is to do alarms.mapValues(hex2Int).map(identity)

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