ClassNotFoundException when deserializing List[T] from redis

[tototoshi]

I encountered ClassNotFoundException when using memoize.
I'm using scalacache-redis 0.5.2.

This script is minimal example to reproduce the error.

case class User(id: Int, name: String)

object Test {

  import scalacache._
  import memoization._
  import redis._

  implicit val scalaCache = ScalaCache(RedisCache("localhost", 6379))

  // Works fine when the result type is User, but throws Exception when List[User]
  def getUser(id: Int): List[User] = memoize {
    List(User(id, "Taro"))
  }

  def main(args: Array[String]): Unit = {
    getUser(1)
  }

}

scalacachedebug> r
[info] Running Test
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
[error] (run-main-3a) java.lang.ClassNotFoundException: User
java.lang.ClassNotFoundException: User
        at java.net.URLClassLoader$1.run(URLClassLoader.java:372)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:360)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:344)
        at java.io.ObjectInputStream.resolveClass(ObjectInputStream.java:626)
        at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1613)
        at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1518)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1774)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1351)
        at java.io.ObjectInputStream.readObject(ObjectInputStream.java:371)
        at scala.collection.immutable.List$SerializationProxy.readObject(List.scala:477)
        at sun.reflect.GeneratedMethodAccessor7.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:483)
        at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:1017)
        at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1896)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1801)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1351)
        at java.io.ObjectInputStream.readObject(ObjectInputStream.java:371)
        at scalacache.redis.RedisSerialization$class.deserialize(RedisSerialization.scala:57)
        at scalacache.redis.RedisCache.deserialize(RedisCache.scala:13)
        at scalacache.redis.RedisCache$$anonfun$get$1$$anonfun$apply$1$$anonfun$1.apply(RedisCache.scala:30)
        at scalacache.redis.RedisCache$$anonfun$get$1$$anonfun$apply$1$$anonfun$1.apply(RedisCache.scala:30)
        at scala.Option.map(Option.scala:146)
        at scalacache.redis.RedisCache$$anonfun$get$1$$anonfun$apply$1.apply(RedisCache.scala:30)
        at scalacache.redis.RedisCache$$anonfun$get$1$$anonfun$apply$1.apply(RedisCache.scala:28)
        at scala.concurrent.impl.ExecutionContextImpl$DefaultThreadFactory$$anon$2$$anon$4.block(ExecutionContextImpl.scala:48)
        at scala.concurrent.forkjoin.ForkJoinPool.managedBlock(ForkJoinPool.java:3640)
        at scala.concurrent.impl.ExecutionContextImpl$DefaultThreadFactory$$anon$2.blockOn(ExecutionContextImpl.scala:45)
        at scala.concurrent.package$.blocking(package.scala:123)
        at scalacache.redis.RedisCache$$anonfun$get$1.apply(RedisCache.scala:28)
        at scalacache.redis.RedisCache$$anonfun$get$1.apply(RedisCache.scala:28)
        at scala.concurrent.impl.Future$PromiseCompletingRunnable.liftedTree1$1(Future.scala:24)
        at scala.concurrent.impl.Future$PromiseCompletingRunnable.run(Future.scala:24)
        at scala.concurrent.impl.ExecutionContextImpl$AdaptedForkJoinTask.exec(ExecutionContextImpl.scala:121)
        at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260)
        at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339)
        at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979)
        at scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107)
[trace] Stack trace suppressed: run last compile:run for the full output.
java.lang.RuntimeException: Nonzero exit code: 1
        at scala.sys.package$.error(package.scala:27)
[trace] Stack trace suppressed: run last compile:run for the full output.
[error] (compile:run) Nonzero exit code: 1
[error] Total time: 0 s, completed 2015/03/08 22:19:23

127.0.0.1:6379> keys *
1) "Test.getUser(1)"
127.0.0.1:6379> get Test.getUser(1)
"\x05\xac\xed\x00\x05sr\x002scala.collection.immutable.List$SerializationProxy\x00\x00\x00\x00\x00\x00\x00\x01\x03\x00\x00xpsr\x00\x04Userx\xae\xbf\rY%\x97\xf6\x02\x00\x02I\x00\x02idL\x00\x04namet\x00\x12Ljava/lang/String;xp\x00\x00\x00\x01t\x00\x04Tarosr\x00,scala.collection.immutable.ListSerializeEnd$\x8a\\c[\xf7S\x0bm\x02\x00\x00xpx"

[tototoshi]

I'm using scalacache-redis with Play 2.3, so ObjectInputStream in scalacache-redis can't see the application.classloader of Play. Need to set custom classloader to RedisCache like play-redis.

[cb372]

Play's classloader magic strikes again. Thanks for investigating.

I'll add a customClassloader argument to RedisCache

class RedisCache(client: Jedis, customClassloader: Option[Classloader] = None)(implicit ...)

and use that in RedisSerialization.

I wonder if memcached has this problem as well. That also uses Java serialization.

By the way, I'd be interested to see how you are integrating ScalaCache with Play. I think a Play plugin might be useful for a lot of people.

[tototoshi]

I have not tried but guess scalacache-memcached also has this problem.

play2-memcached plugin do the same thing as play-redis.
https://github.com/mumoshu/play2-memcached/blob/master/plugin/src/main/scala/com/github/mumoshu/play2/memcached/MemcachedPlugin.scala#L80-L86

Writing the backend of Play Cache API with the implementation of scalacache-redis and scalacache-memcached is a good idea. play2-memcached and play-redis don't seem to be good maintained but a lot of people are using them. I hardly use Play Cache API directly, but some popular modules (securesocial, play2-auth...) depend on the API.

[cb372]

In scalacache-redis 0.6.0 I've added a constructor argument so you can pass in app.classloader and it will be used for deserialization.

While investigating this issue I noticed that scalacache-redis was not thread-safe, so I've fixed that as well.

[tototoshi]

👍

[cb372]

An interesting development: this is actually a Scala/Openjdk bug. https://issues.scala-lang.org/browse/SI-9237