Hazelcast instance used for 2nd Hibernate cache cannot connect stably in Kubernetes

Question

Iam using embedded Hazelcast deployed in Kubernetes(GKE) to enable 2nd level cache Hibernate in Spring Boot application. Spingboot app connect to Spanner by using spanner-jdbc (https://github.com/olavloite/spanner-jdbc). I deploy 1 service (replicas=2) to k8s, however hazelcast instances located in 2 pods cannot connect stably (it works when server starts but then seem disconnected after, please the below log). This causes 2nd level cache cannot be shared between 2 pods. Anyone can help this situation? Thank you.

<groupId>com.hazelcast.poc</groupId>
<artifactId>hazelcast-poc</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>hazelcast-poc</name>
<description>Demo project for Spring Boot</description>

<properties>
    <java.version>1.8</java.version>
</properties>

<dependencies>
    <dependency>
        <groupId>nl.topicus</groupId>
        <artifactId>spanner-jdbc</artifactId>
        <version>1.0.8</version>
    </dependency>

    <dependency>
        <groupId>nl.topicus</groupId>
        <artifactId>spanner-hibernate</artifactId>
        <version>0.7</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-rest</artifactId>
    </dependency>
    <dependency>
        <groupId>com.hazelcast</groupId>
        <artifactId>hazelcast</artifactId>
        <version>3.11</version>
    </dependency>
    <dependency>
        <groupId>com.hazelcast</groupId>
        <artifactId>hazelcast-hibernate5</artifactId>
        <version>1.3.0</version>
    </dependency>
    <dependency>
        <groupId>com.hazelcast</groupId>
        <artifactId>hazelcast-kubernetes</artifactId>
        <version>1.3.1</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>

    <dependency>
        <groupId>org.assertj</groupId>
        <artifactId>assertj-core</artifactId>
        <version>3.8.0</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.hamcrest</groupId>
        <artifactId>hamcrest-all</artifactId>
        <version>1.3</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.uuid</groupId>
        <artifactId>java-uuid-generator</artifactId>
        <version>3.1.5</version>
    </dependency>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-java8</artifactId>
        <version>${hibernate.version}</version>
    </dependency>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
            <version>2.0.1.RELEASE</version>
            <executions>
                <execution>
                    <goals>
                        <goal>repackage</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.8.0</version>
            <configuration>
                <source>1.8</source>
                <target>1.8</target>
                <encoding>UTF-8</encoding>
            </configuration>
        </plugin>
    </plugins>
</build>

Springboot Application.java:

public static void main(String[] args) throws IOException {
    CloudSpannerDriver.setLogLevel(CloudSpannerDriver.DEBUG);
    Writer writer = new FileWriter("jdbc.log", false);
    DriverManager.setLogWriter(new PrintWriter(writer));SpringApplication.run(Application.class, args);
}

@Bean
public Config hazelCastConfig(){
    Config config = new Config();
    config
            .addMapConfig(
                    new MapConfig()
                            .setName("employees")
                            .setMaxSizeConfig(new MaxSizeConfig(200, MaxSizeConfig.MaxSizePolicy.FREE_HEAP_SIZE))
                            .setEvictionPolicy(EvictionPolicy.LRU)
                            .setTimeToLiveSeconds(20000));
    JoinConfig joinConfig = config.getNetworkConfig().getJoin();
    joinConfig.getMulticastConfig().setEnabled(false);
    joinConfig.getKubernetesConfig().setEnabled(true).setProperty("namespace", "default");

    return config;
}

}

deployment.yaml:

apiVersion: apps/v1
kind: Deployment
metadata:
 name: hazelcast-embedded-0
spec:
  replicas: 2
  selector:
  matchLabels:
  app: hazelcast-embedded-0
  template:
   metadata:
    labels:
      app: hazelcast-embedded-0
    spec:
    volumes:
      - name: hazelcast-key
        secret:
        secretName: hazelcast-key
  containers:
    - name: hazelcast-embedded
      image: gcr.io/testproject-221915/hazelcast- poc@sha256:5a103d7e2e56c46e9e42617232e472891bda5d121139fe7e41057596bd71bf00
      imagePullPolicy: Always
      volumeMounts:
        - name: hazelcast-key
          mountPath: /var/secrets/google
      env:
      - name: GOOGLE_APPLICATION_CREDENTIALS
        value: /var/secrets/google/key.json
      ports:
       - containerPort: 5701
       - containerPort: 8080


  apiVersion: v1
  kind: Service
  metadata:
  name: hazelcast-embedded-0
  spec:
   type: LoadBalancer
   selector:
    app: hazelcast-embedded-0
   ports:
   - name: hazelcast
    port: 5701
   - name: app
     port: 8080

Spanner Datasource file:

@Bean
public LocalContainerEntityManagerFactoryBean spannerEntityManager() {
    LocalContainerEntityManagerFactoryBean em = new LocalContainerEntityManagerFactoryBean();
    em.setDataSource(spannerDataSource());
    em.setPersistenceUnitName("SpannerPU");
    HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
    em.setJpaVendorAdapter(vendorAdapter);
    HashMap<String, Object> properties = new HashMap<>();
    properties.put("hibernate.dialect", "nl.topicus.hibernate.dialect.CloudSpannerDialect");
    properties.put("hibernate.temp.use_jdbc_metadata_defaults", false);
    properties.put("hibernate.show_sql", showSql);
    properties.put("hibernate.format_sql", formatSql);
    properties.put("hibernate.cache.use_query_cache", true);
    properties.put("hibernate.cache.use_second_level_cache", true);
    properties.put("hibernate.cache.region.factory_class", "com.hazelcast.hibernate.HazelcastCacheRegionFactory");
    if("development".equals(profileActive)) {
        properties.put("hibernate.generate_statistics", statistic);
        properties.put("org.hibernate.stat", hibernateStat);            
    }        
    em.setJpaPropertyMap(properties);

    return em;
}

Application.properties

spanner.datasource.className=nl.topicus.jdbc.CloudSpannerDriver
spanner.datasource.url=jdbc:cloudspanner://;Project=testproject- 
221915;Instance=test-hazelcast;Database=hazelcast
spanner.hibernate.dialect=
 nl.topicus.hibernate.dialect.CloudSpannerDialect
spanner.hibernate.show-sql=true
spanner.hibernate.format_sql=true
spanner.datasource.hikari.maximum-pool-size=2 #depend on 
 microservice
spanner.datasource.hikari.minimum-idle=2
spanner.datasource.hikari.connection-timeout=60000

spring.profiles.active=dev
hibernate.generate_statistics=true
org.hibernate.stat=DEBUG

Log_pod1 Log_pod2

As you see, the second log has only 1 member whereas the first has 2 members. I tested by issuing rest request to service which then distributed to each pods, the test result is sometimes cache are shared between two pods, sometimes not.

I expected 2nd Hibernate cache should be shared between 2 pods in the service

Answer 1

You are creating two Hazelcast instances

At 9:36:44.990 a kubernetes discovery instance

At 9:36:53.706 a multicast discovery instance

Might be this again

Set hibernate.cache.hazelcast.instance_name system property and config.setInstanceName("whatever") pairing should match