[FLINK-17320] Java8 lambda expression cannot be serialized.

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Won't Fix
• Affects Version/s: 1.9.0
• Component/s: API / Type Serialization System, Table SQL / Runtime
• Labels: stale-major
• Assignee: Unassigned
• Reporter: Jiayi Liao
• Created: 22/Apr/20 07:46
• Updated: 22/Apr/21 11:34
• Resolved: 22/Apr/21 11:34

Description

It happens when we want to use java.util.PriorityQueue in customed UDAF. The serialization error occurs with codes below.

@Test
public void test() throws IOException {
        PriorityQueue<String> pq = new PriorityQueue<>((o1, o2) -> o1.length - o2.length - 1);
        pq.add("1234135");
        pq.add("12323424135");

        KryoSerializer kryoSerializer = new KryoSerializer(PriorityQueue.class, new ExecutionConfig());
        kryoSerializer.serialize(pq, new DataOutputSerializer(10240));
}

And the NPE will be thrown:

Caused by: java.lang.NullPointerException
        at com.esotericsoftware.kryo.util.DefaultClassResolver.writeClass(DefaultClassResolver.java:80)
        at com.esotericsoftware.kryo.Kryo.writeClass(Kryo.java:488)
        at com.esotericsoftware.kryo.Kryo.writeClassAndObject(Kryo.java:593)
        at org.apache.flink.runtime.types.PriorityQueueSerializer.write(PriorityQueueSerializer.java:67)
        at org.apache.flink.runtime.types.PriorityQueueSerializer.write(PriorityQueueSerializer.java:40)
        at com.esotericsoftware.kryo.Kryo.writeClassAndObject(Kryo.java:599)
        at org.apache.flink.api.java.typeutils.runtime.kryo.KryoSerializer.serialize(KryoSerializer.java:307)
        at org.apache.flink.util.InstantiationUtil.serializeToByteArray(InstantiationUtil.java:526)

Issue Links

• links to: issue in twitter/chill