flink-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-1325) Add a closure cleaner for Java
Date Wed, 17 Dec 2014 12:55:13 GMT

    [ https://issues.apache.org/jira/browse/FLINK-1325?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14249802#comment-14249802
] 

ASF GitHub Bot commented on FLINK-1325:
---------------------------------------

Github user aljoscha commented on a diff in the pull request:

    https://github.com/apache/incubator-flink/pull/273#discussion_r21969545
  
    --- Diff: flink-addons/flink-streaming/flink-streaming-core/src/main/java/org/apache/flink/streaming/api/datastream/ConnectedDataStream.java
---
    @@ -402,10 +415,10 @@ protected ConnectedDataStream(ConnectedDataStream<IN1, IN2>
coDataStream) {
     	 */
     	public <OUT> SingleOutputStreamOperator<OUT, ?> map(CoMapFunction<IN1,
IN2, OUT> coMapper) {
     		TypeInformation<OUT> outTypeInfo = TypeExtractor.createTypeInfo(CoMapFunction.class,
    -				coMapper.getClass(), 2, null, null);
    +				clean(coMapper).getClass(), 2, null, null);
    --- End diff --
    
    We don't need the extra cleaning before the .getClass() method. This also applied to the
other parts in this PR where that pattern occurs.


> Add a closure cleaner for Java
> ------------------------------
>
>                 Key: FLINK-1325
>                 URL: https://issues.apache.org/jira/browse/FLINK-1325
>             Project: Flink
>          Issue Type: Improvement
>          Components: Java API
>            Reporter: Stephan Ewen
>            Assignee: Aljoscha Krettek
>             Fix For: 0.8-incubating
>
>
> The Java API could really need a simple closure cleaner.
> All functions that are implemented as anonymous subclasses hold a reference to the enclosing
class, unless they are implemented as part of a static method.
> That reference (called {{this$0}}) causes serialization to fail, as it draws non serializable
classes into the function, even in cases where the function makes no access to the enclosing
data.
> It is possible to manually set this reference to {{null}}, using reflection, or using
a debugger. Then the serialization succeeds.
> I suggest to add a closure cleaner that uses an ASM visitor over the function's code
to see if there is any access to the {{this$0}} field. In case there is non, the field should
be set to {{null}}.
> The problem can be reproduced with the simple program below:
> {code}
> public class Test {
>   public void runProgram() throws Exception {
>     ExecutionEnvironment env = ExecutionEnvironment .getExecutionEnvironment();
>     env.generateSequence(1, 10)
>         .map(new MapFunction<Long, Long>() {
>           public Long map(Long value) {
>             return value * 2;
>           }
>         })
>         .print();
>     env.execute();
>   }
>   public static void main(String[] args) throws Exception {
>     new Test().runProgram();
>   }
> }
> {code}



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

Mime
View raw message