浅谈Spark Kryo serialization

分手后的思念是犯贱 2022-04-10 03:54 145阅读 0赞

最近在使用spark开发过程中发现当数据量很大时，如果cache数据将消耗很多的内存。为了减少内存的消耗，测试了一下 Kryo serialization的使用

代码包含三个类，KryoTest、MyRegistrator、Qualify。

我们知道在Spark默认使用的是Java自带的序列化机制。如果想使用Kryo serialization，只需要添加KryoTest类中的红色部分，指定spark序列化类

另外还需要增加MyRegistrator类，注册需要用Kryo序列化的类

public class KryoTest {
        public static void main(String[] args) {
            SparkConf conf = new SparkConf();
            conf.setMaster("local");
            conf.setAppName("KryoTest");
            conf.set("spark.serializer", "org.apache.spark.serializer.KryoSerializer");
            conf.set("spark.kryo.registrator", "MyRegistrator");
            
            JavaSparkContext sc = new JavaSparkContext(conf);
    
            JavaRDD<String> rdd = sc.textFile("/home/hdpusr/qualifying.txt");
            JavaRDD<Qualify> map = rdd.map(new Function<String, Qualify>() {
                /* (non-Javadoc)
                 * @see org.apache.spark.api.java.function.Function#call(java.lang.Object)
                 */
                public Qualify call(String v1) throws Exception {
                    // TODO Auto-generated method stub
                    String s[] =  v1.split(",");
                    Qualify q = new Qualify();
                    q.setA(Integer.parseInt(s[0]));
                    q.setB(Long.parseLong(s[1]));
                    q.setC(s[2]);
                    
                    
                    return q;
                }
            });
            map.persist(StorageLevel.MEMORY_AND_DISK_SER());
            System.out.println(map.count());
        }
    }

import org.apache.spark.serializer.KryoRegistrator;
    
    import com.esotericsoftware.kryo.Kryo;
    
    public class MyRegistrator implements KryoRegistrator{
        /* (non-Javadoc)
         * @see org.apache.spark.serializer.KryoRegistrator#registerClasses(com.esotericsoftware.kryo.Kryo)
         */
        public void registerClasses(Kryo arg0) {
            // TODO Auto-generated method stub
            arg0.register(Qualify.class);
        }
    }

import java.io.Serializable;
    
    
    public class Qualify implements Serializable{
        int a;
        long b;
        String c;
        public int getA() {
            return a;
        }
        public void setA(int a) {
            this.a = a;
        }
        public long getB() {
            return b;
        }
        public void setB(long b) {
            this.b = b;
        }
        public String getC() {
            return c;
        }
        public void setC(String c) {
            this.c = c;
        }
        
    }

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##### 转自：[http://www.cnblogs.com/tovin/p/3833985.html][http_www.cnblogs.com_tovin_p_3833985.html] #####

[http_www.cnblogs.com_tovin_p_3833985.html]: http://www.cnblogs.com/tovin/p/3833985.html