如果是临时实例，则不会在Nacos服务端持久化存储，需要通过上报心跳的方式进行保活，如果一段时间内没有上报心跳，则会被Nacos服务端摘除。
在被摘除后如果又开始上报心跳，则会重新将这个实例注册。
持久化实例则会持久化到Nacos服务端，此时即使注册实例的客户端进程不在，这个实例也不会从服务端删除，只会将健康状态设为不健康。
同一个服务下可以同时有临时实例和持久化实例，这意味着当这服务的所有实例进程不在时，会有部分实例从服务上摘除，剩下的实例则会保留在服务下

~/.SpaceVim/init.toml

guifont= "Hack NF:h11"

FileChannel channel = new RandomAccessFile(file, "rw").getChannel();
try(FileLock lock = channel.tryLock()) {
if (lock == null) {
log.debug("lock on file:{}", file.getPath());
// do something
// 花了很多时间
} else {

}
}

Whether or not a lock actually prevents another program from accessing
the content of the locked region is system-dependent and therefore
unspecified. The native file-locking facilities of some systems are merely
advisory, meaning that programs must cooperatively observe a known
locking protocol in order to guarantee data integrity. On other systems
native file locks are mandatory, meaning that if one program locks a
region of a file then other programs are actually prevented from accessing
that region in a way that would violate the lock. On yet other systems,
whether native file locks are advisory or mandatory is configurable on a
per-file basis. To ensure consistent and correct behavior across platforms,
it is strongly recommended that the locks provided by this API be used as if
they were advisory locks.

cat /proc/locks

mount -o mand /dev/sdb7 /mnt

[local]
192.168.100.129
[dw]
192.168.100.130
192.168.100.131
192.168.100.132

- name: mkdir
shell: mkdir -p /root/java/
- name: copy jdk to remote host
copy: src=jdk-8u161-linux-x64.tar.gz dest=/root/java/
- name: unzip jdk
shell: tar -zxf /root/java/jdk-8u161-linux-x64.tar.gz -C /root/java/
- name: set jdk_env copy use template
template: src=java_home.sh.j2 dest=/root/java/set_jdk.sh
- name: execute script to set jdkenv
shell: sh /root/java/set_jdk.sh
- name: source bash_profile
shell: source /root/.bash_profile

ansible-playbook playbook/roles/java/tasks/main.yml

The error appears to have been in '/etc/ansible/playbook/roles/java/tasks/main.yml': line 1, column 1, but may
be elsewhere in the file depending on the exact syntax problem.

The offending line appears to be:

- name: mkdir
^ here

PLAY [dw] ***********************************************************************************************************************************************************************************************************

TASK [Gathering Facts] **********************************************************************************************************************************************************************************************
ok: [192.168.100.131]
ok: [192.168.100.132]
ok: [192.168.100.130]

TASK [mkdir] ********************************************************************************************************************************************************************************************************
 [WARNING]: Consider using the file module with state=directory rather than running mkdir.  If you need to use command because file is insufficient you can add warn=False to this command task or set
command_warnings=False in ansible.cfg to get rid of this message.

changed: [192.168.100.130]
changed: [192.168.100.132]
changed: [192.168.100.131]

TASK [copy jdk to remote host] **************************************************************************************************************************************************************************************
changed: [192.168.100.132]
changed: [192.168.100.130]
changed: [192.168.100.131]

TASK [unzip jdk] ****************************************************************************************************************************************************************************************************
 [WARNING]: Consider using the unarchive module rather than running tar.  If you need to use command because unarchive is insufficient you can add warn=False to this command task or set command_warnings=False in
ansible.cfg to get rid of this message.

changed: [192.168.100.130]
changed: [192.168.100.131]
changed: [192.168.100.132]

TASK [set jdk_env copy use template] ********************************************************************************************************************************************************************************
changed: [192.168.100.130]
changed: [192.168.100.131]
changed: [192.168.100.132]

TASK [execute script to set jdkenv] *********************************************************************************************************************************************************************************
changed: [192.168.100.130]
changed: [192.168.100.131]
changed: [192.168.100.132]

TASK [source bash_profile] ******************************************************************************************************************************************************************************************
changed: [192.168.100.130]
changed: [192.168.100.131]
changed: [192.168.100.132]

PLAY RECAP **********************************************************************************************************************************************************************************************************
192.168.100.130            : ok=7    changed=6    unreachable=0    failed=0   
192.168.100.131            : ok=7    changed=6    unreachable=0    failed=0   
192.168.100.132            : ok=7    changed=6    unreachable=0    failed=0

object Recommender {
  private val log = Logger(Recommender.getClass)

  // load config
  private val config = ConfigFactory.load("config.properties")

  // spark config
  private val appName = config.getString("appName")
  private val mode = config.getString("mode")


  def main(args: Array[String]): Unit = {
    log.info("init {}，mode:{}", appName, mode)

    // init spark
    val sc = new SparkConf()
      .setAppName(appName)
      .setMaster(mode)
      .set("spark.serializer", "org.apache.spark.serializer.KryoSerializer")


    val session = SparkSession.builder().config(sc).getOrCreate()
    try {
      initMat(session)

      var headMap = new mutable.LinkedHashMap[String, Int]()
      headMap.put("ID", 0)
      headMap.put("UID", 1)

      val headBroadcast = ss.sparkContext.broadcast[mutable.LinkedHashMap[String, Int]](headMap)

      // 略...


    } finally {
      session.close()
    }
  }
}

def main(args: Array[String]): Unit = {
    var headMap = new mutable.LinkedHashMap[String, Int]()
    headMap.put("a", 1)
    headMap.put("b", 2)
    headMap.put("c", 3)
    //
    val kryo = new Kryo()
    val output = new Output(new FileOutputStream("e:\\ser.bin"))
    kryo.writeObject(output, headMap)
  }

kryo.register(classOf[mutable.HashMap[String, (String, String)]], new JavaSerializer)

cannot assign instance of java.lang.invoke.SerializedLambda to field

java.lang.NoClassDefFoundError: Could not initialize class Main

/**
* @author liuxinsi
* @mail akalxs@gmail.com
 */
public class Main {

private static final JavaSparkContext sc = new JavaSparkContext(
new SparkConf().setAppName(“Loader”).setMaster(“yarn”)
);

private static final SQLContext sqlContext = new SQLContext(sc);

public static void main(String[]() args) {
    DataFrame df = sqlContext.read().json("data.json");
    // 一些基本操作，略...
}
}

/**
* @author liuxinsi
* @mail akalxs@gmail.com
 */
public class Main {

public static void main(String[]() args) {
    JavaSparkContext sc = new JavaSparkContext(
        new SparkConf().setAppName(“Loader”).setMaster(“yarn”)
    );

    SQLContext sqlContext = new SQLContext(sc);

    DataFrame df = sqlContext.read().json("data.json");
    // 一些基本操作，略...
}
}

/**
 * 响应对象。<br/>
 * {@link #errMesg}和{@link #errDetail}仅在状态{@link #status}为{@link Status#ERROR}时出现。
 *
 * @author liuxinsi
 * @mail akalxs@gmail.com
 */
@Data
public class Response<T> {
    /**
     * 业务数据
     */
    private T data;
    /**
     * 响应状态
     */
    private Status status;
    /**
     * 错误消息
     */
    private String errMesg;
    /**
     * 错误堆栈
     */
    private String errDetail;

    public enum Status {
        SUCCESS, ERROR;
    }
}

/**
 * 对应{@link com.lxs.mms.auth.resource.AuthenticationResource#validateToken(ValidateTokenRequest)} 响应。
 *
 * @author liuxinsi
 * @mail akalxs@gmail.com
 */
@Data
@ApiModel(value = "验证Token响应")
public class ValidateTokenResponse {
    @ApiModelProperty(value = "Token是否合法,true合法，false非法。")
    private Boolean legally;
    @ApiModelProperty(value = "Token中的Audience属性")
    private String audience;
    @ApiModelProperty(value = "描述")
    private String desc;

}

Gson gson = new Gson();
Type jsonType = new TypeToken<Response<ValidateTokenResponse>>() {
}.getType();
Response<ValidateTokenResponse> r=gson.fromJson(json, jsonType);

public static <T> Response<T> unwrap(String json) {
        Gson gson = new Gson();
        Type jsonType = new TypeToken<Response<T>>() {
        }.getType();
        return gson.fromJson(json, jsonType);
    }

public static <T> Response<T> unwrap(String json, Class<?> clazz) {
       return gson.fromJson(json, new ParameterizedType() {
           /**
           * 原始类型实际的泛型类，与外部传入<code>clazz</code>显示指明。
           */
           @Override
           public Type[] getActualTypeArguments() {
               return new Class[]{clazz};
           }

           /**
           * 原始类型。
           */
           @Override
           public Type getRawType() {
               return Response.class;
           }
           
           /**
           * 如果是内部类需要指明所属的对象，如果不是返回null。
           */
           @Override
           public Type getOwnerType() {
               return null;
           }
       });

   }

Response<ValidateTokenResponse> r = ResponseUnwrap.unwrap(json,ValidateTokenResponse.class);