hello,我这边测试了一下发现一个问题，在使用String类型做keyby的时候并没有得到正确的结果，而使用int类型的时候结果是正确。而且测试发现两次keyby确实是以第二次keyby为准
下面是我的代码及测试结果
一.使用int类型
public class KeyByTest {
public static void main(String[] args) throws Exception {
StreamExecutionEnvironment env =
StreamExecutionEnvironment.getExecutionEnvironment();
env.setParallelism(10);
DataStreamSource<data> dataDataStreamSource =
env.fromCollection(Arrays.asList(new data(1, "123", "首页"),
new data(1, "123", "分类页"),
new data(2, "r-123", "搜索结果页"),
new data(1, "r-123", "我的页"),
new data(3, "r-4567", "搜索结果页")));
SingleOutputStreamOperator<String> map = dataDataStreamSource.keyBy(new
MyKeySelector())
.map(new RichMapFunction<data, String>() {
@Override
public String map(data data) throws Exception {
System.out.println(data.toString() + "的subtask为:" +
getRuntimeContext().getIndexOfThisSubtask() );
return data.toString();
}
});
env.execute("test");
}
}
class data{
private int id;
private String goods;
private String pageName;
public data(int id, String goods, String pageName) {
this.id = id;
this.goods = goods;
this.pageName = pageName;
}
public data() {
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getGoods() {
return goods;
}
public void setGoods(String goods) {
this.goods = goods;
}
public String getPageName() {
return pageName;
}
public void setPageName(String pageName) {
this.pageName = pageName;
}
@Override
public String toString() {
return "data{" +
"id='" + id + '\'' +
", goods='" + goods + '\'' +
", pageName='" + pageName + '\'' +
'}';
}
}
class MyKeySelector implements KeySelector<data,Integer>{
@Override
public Integer getKey(data data) throws Exception {
return data.getId();
}
}
控制台的输出如下:
可以看见数据根据id分组，分到了不同的subtask上。
二.使用String类型 代码如下:
public class KeyByTest {
public static void main(String[] args) throws Exception {
StreamExecutionEnvironment env =
StreamExecutionEnvironment.getExecutionEnvironment();
env.setParallelism(10);
DataStreamSource<data> dataDataStreamSource =
env.fromCollection(Arrays.asList(new data("1", "123", "首页"),
new data("1", "123", "分类页"),
new data("2", "r-123", "搜索结果页"),
new data("2", "r-123", "我的页"),
new data("3", "r-4567", "搜索结果页")));
SingleOutputStreamOperator<String> map = dataDataStreamSource.keyBy(new
MyKeySelector())
.map(new RichMapFunction<data, String>() {
@Override
public String map(data data) throws Exception {
System.out.println(data.toString() + "的subtask为:" +
getRuntimeContext().getIndexOfThisSubtask() );
return data.toString();
}
});
env.execute("test");
}
}
class data{
private String id;
private String goods;
private String pageName;
public data(String id, String goods, String pageName) {
this.id = id;
this.goods = goods;
this.pageName = pageName;
}
public data() {
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getGoods() {
return goods;
}
public void setGoods(String goods) {
this.goods = goods;
}
public String getPageName() {
return pageName;
}
public void setPageName(String pageName) {
this.pageName = pageName;
}
@Override
public String toString() {
return "data{" +
"id='" + id + '\'' +
", goods='" + goods + '\'' +
", pageName='" + pageName + '\'' +
'}';
}
}
class MyKeySelector implements KeySelector<data,String>{
@Override
public String getKey(data data) throws Exception {
return data.getId();
}
}
最终控制台输出如下:
可以看见只分了两个组，我不清楚这是否是一个bug.
lxk7...@163.com
From: Xuyang
Date: 2022-05-24 21:35
To: user-zh
Subject: Re:Re: Re: Some question with Flink state
我不确定但大概率是两次keyby只以后面那个为准，所以可能会导致你前面的keyby其实是无用的（可以试验下）。<br/><br/>可以按你说的方式将数据中这两个key拼成一个string当作shuffle的key。
在 2022-05-24 21:06:58，"lxk7...@163.com" <lxk7...@163.com> 写道：
>如果是两次keyby的问题，我可以直接在一次keyby里将两个数据给拼接成字符串，这样的方式是跟两次keyby效果一样吗？
>
>
>
>lxk7...@163.com
>
>From: Xuyang
>Date: 2022-05-24 20:51
>To: user-zh
>Subject: Re:Re: Re: Some question with Flink state
>看起来你keyby了两次，可以自定义一个keyselector来替代这两个。另外如果担心相同key没有被分到同一个并行度时，可以在某个并行度的算子下将数据和该subtask的并行度index打出来，debug调查下
>在 2022-05-24 20:43:19，"lxk7...@163.com" <lxk7...@163.com> 写道：
>>
>>https://s2.loli.net/2022/05/24/SgAWefJpaxtOH5l.png
>>https://s2.loli.net/2022/05/24/54dZkr19QCh3Djf.png
>>
>>这样呢
>>
>>
>>lxk7...@163.com
>>
>>From: Xuyang
>>Date: 2022-05-24 20:17
>>To: user-zh
>>Subject: Re:Re: Re: Some question with Flink state
>>Hi, 你的图还是挂了，可以使用图床工具试一下
>>
>>
>>
>>在 2022-05-24 13:50:34，"lxk7...@163.com" <lxk7...@163.com> 写道：
>>
>>图片好像有点问题，重新上传一下
>>lxk7...@163.com
>>From: Hangxiang Yu
>>Date: 2022-05-24 12:09
>>To: user-zh
>>Subject: Re: Re: Some question with Flink state
>>你是用data stream作业吗，相同key如果分配到了不同的并行度，有可能是和你写的key
>>selector相关（你可以参照下KeySelector的comments去看是否符合它的规范）；
>>或者方便的话你可以分享下你的key selector相关的逻辑和使用state的逻辑；
>>On Tue, May 24, 2022 at 9:59 AM lxk7...@163.com <lxk7...@163.com> wrote:
>>> 好的，我看这里面邮件都是英文，所以用英文问了个问题。
>>>
>>> 我再描述一下我的问题，我使用键控状态，用的value-state。按理来说，相同的key应该会被分到同一个并行度处理。但是但我使用多个并行度的时候，我发现好像相同的key并没有分配到同一个并行度处理。具体现象在于，我的程序是对同一个用户点击的商品进行累加，在数据里这个商品已经是第二个了，但是程序里这个商品的状态是空，所以导致最终累加的结果是1，而正确结果应该是2。所以我猜测是不是算子对于value-state都是独有的。
>>>
>>> 但是当我使用mapstate的时候，这个问题好像就没有再出现了。所以我想了解这里面的原因是啥？或者有什么方法能确保同一个key的数据都会被同一个task处理。
>>>
>>>
>>>
>>> lxk7...@163.com
>>>
>>> From: Hangxiang Yu
>>> Date: 2022-05-23 23:09
>>> To: user-zh; lxk7491
>>> Subject: Re: Some question with Flink state
>>> Hello,
>>> All states will not be shared in different parallelisms.
>>> BTW, English questions could be sent to u...@flink.apache.org.
>>>
>>> Best,
>>> Hangxiang.
>>>
>>> On Mon, May 23, 2022 at 4:03 PM lxk7...@163.com <lxk7...@163.com> wrote:
>>>
>>> >
>>> > Hi everyone
>>> > I was used Flink keyed-state in my Project.But I found some questions
>>> > that make me confused.
>>> > when I used value-state in multi parallelism the value is not I
>>> wanted.
>>> > So I guess that value-state is in every parallelism. every parallelism
>>> > saved their only value which means the value is Thread-Level
>>> > But when I used map-state,the value is correctly. I mean the map-state
>>> > was shared by every parallelism.
>>> > looking forward to your reply
>>> >
>>> >
>>> > lxk7...@163.com
>>> >
>>>
