Skywalking-06：OAL基础

红太狼 2022-09-02 12:57 180阅读 0赞

# `OAL` 基础知识 #

## 基本介绍 ##

> `OAL(Observability Analysis Language)` 是一门用来分析流式数据的语言。
> 
> 因为 `OAL` 聚焦于度量 `Service` 、 `Service Instance` 和 `Endpoint` 的指标，所以它学习和使用起来非常简单。
> 
> `OAL` 基于 `altlr` 与 `javassist` 将 `oal` 脚本转化为动态生成的类文件。
> 
> 自从 `6.3` 版本后， `OAL` 引擎内置在 `OAP` 服务器中，可以看做 `oal-rt(OAL Runtime)` 。 `OAL` 脚本位置 `OAL` 配置目录下( `/config/oal` )，使用者能够更改脚本并重启生效。注意： `OAL` 脚本仍然是一门编译语言， `oal-rt` 动态的生成 `Java` 代码。
> 
> 如果你配置了环境变量 `SW_OAL_ENGINE_DEBUG=Y`，能在工作目录下的 `oal-rt` 目录下找到生成的 `Class` 文件。

## 语法 ##

// 声明一个指标
    METRICS_NAME = from(SCOPE.(* | [FIELD][,FIELD ...])) // 从某一个SCOPE中获取数据
    [.filter(FIELD OP [INT | STRING])] // 可以过滤掉部分数据
    .FUNCTION([PARAM][, PARAM ...]) // 使用某个聚合函数将数据聚合
    
    // 禁用一个指标
    disable(METRICS_NAME);

## 语法案例 ##

`oap-server/server-bootstrap/src/main/resources/oal/java-agent.oal`

// 从ServiceInstanceJVMMemory的used获取数据，只需要 heapStatus 为 true的数据，并取long型的平均值
    instance_jvm_memory_heap = from(ServiceInstanceJVMMemory.used).filter(heapStatus == true).longAvg();

`org.apache.skywalking.oap.server.core.source.ServiceInstanceJVMMemory`

@ScopeDeclaration(id = SERVICE_INSTANCE_JVM_MEMORY, name = "ServiceInstanceJVMMemory", catalog = SERVICE_INSTANCE_CATALOG_NAME)
    @ScopeDefaultColumn.VirtualColumnDefinition(fieldName = "entityId", columnName = "entity_id", isID = true, type = String.class)
    public class ServiceInstanceJVMMemory extends Source { 
        @Override
        public int scope() { 
            return DefaultScopeDefine.SERVICE_INSTANCE_JVM_MEMORY;
        }
    
        @Override
        public String getEntityId() { 
            return String.valueOf(id);
        }
    
        @Getter @Setter
        private String id;
        @Getter @Setter @ScopeDefaultColumn.DefinedByField(columnName = "name", requireDynamicActive = true)
        private String name;
        @Getter @Setter @ScopeDefaultColumn.DefinedByField(columnName = "service_name", requireDynamicActive = true)
        private String serviceName;
        @Getter @Setter @ScopeDefaultColumn.DefinedByField(columnName = "service_id")
        private String serviceId;
        @Getter @Setter
        private boolean heapStatus;
        @Getter @Setter
        private long init;
        @Getter @Setter
        private long max;
        @Getter @Setter
        private long used;
        @Getter @Setter
        private long committed;
    }

可供参考的官方文档：[Observability Analysis Language][]

# 从一个案例开始分析 `OAL` 原理 #

## 缺少的类加载信息监控 ##

默认的 `APM/Instance` 页面，缺少关于 `JVM Class` 的信息（如下图所示），故这次将相关信息补齐。由这次案例来分析 `OAL` 的原理。

![file][]

在 [Skywalking-04：扩展Metric监控信息][Skywalking-04_Metric] 中，讲到了如何在已有 `Source` 类的情况下，增加一些指标。

这次直接连 `Source` 类以及 `OAL` 词法语法关键字都自己定义。

可供参考的官方文档：[Source and Scope extension for new metrics][]

## 确定增加的指标 ##

通过[Java ManagementFactory解析][Java ManagementFactory]这篇文章，可以确定监控指标为“当前加载类的数量”、“已卸载类的数量”、“一共加载类的数量”三个指标

ClassLoadingMXBean classLoadingMXBean = ManagementFactory.getClassLoadingMXBean();
    // 当前加载类的数量
    int loadedClassCount = classLoadingMXBean.getLoadedClassCount();
    // 已卸载类的数量
    long unloadedClassCount = classLoadingMXBean.getUnloadedClassCount();
    // 一共加载类的数量
    long totalLoadedClassCount = classLoadingMXBean.getTotalLoadedClassCount();

## 定义 `agent` 与 `oap server` 通讯类 ##

在 `apm-protocol/apm-network/src/main/proto/language-agent/JVMMetric.proto` 协议文件中增加如下定义。

在 `apm-protocol/apm-network` 目录下执行 `mvn clean package -DskipTests=true` 会生成新的相关 `Java` 类，`org.apache.skywalking.apm.network.language.agent.v3.Class` 该类就是我们在代码中实际操作的类。

message Class {
      int64 loadedClassCount = 1;
      int64 unloadedClassCount = 3;
      int64 totalLoadedClassCount = 2;
    }
    
    message JVMMetric {
        int64 time = 1;
        CPU cpu = 2;
        repeated Memory memory = 3;
        repeated MemoryPool memoryPool = 4;
        repeated GC gc = 5;
        Thread thread = 6;
        // 在JVM指标中添加Class的定义
        Class clazz = 7;
    }

## 收集 `agent` 的信息后，将信息发送至 `oap server` ##

收集 `Class` 相关的指标信息

package org.apache.skywalking.apm.agent.core.jvm.clazz;
    
    import org.apache.skywalking.apm.network.language.agent.v3.Class;
    
    import java.lang.management.ClassLoadingMXBean;
    import java.lang.management.ManagementFactory;
    
    public enum ClassProvider { 
        /** * instance */
        INSTANCE;
    
        private final ClassLoadingMXBean classLoadingMXBean;
    
        ClassProvider() { 
            this.classLoadingMXBean = ManagementFactory.getClassLoadingMXBean();
        }
    	
        // 构建class的指标信息
        public Class getClassMetrics() { 
            int loadedClassCount = classLoadingMXBean.getLoadedClassCount();
            long unloadedClassCount = classLoadingMXBean.getUnloadedClassCount();
            long totalLoadedClassCount = classLoadingMXBean.getTotalLoadedClassCount();
            return Class.newBuilder().setLoadedClassCount(loadedClassCount)
                    .setUnloadedClassCount(unloadedClassCount)
                    .setTotalLoadedClassCount(totalLoadedClassCount)
                    .build();
        }
    
    }

在 `org.apache.skywalking.apm.agent.core.jvm.JVMService#run` 方法中，将 `class` 相关指标设置到 `JVM` 指标类中

@Override
        public void run() { 
            long currentTimeMillis = System.currentTimeMillis();
            try { 
                JVMMetric.Builder jvmBuilder = JVMMetric.newBuilder();
                jvmBuilder.setTime(currentTimeMillis);
                jvmBuilder.setCpu(CPUProvider.INSTANCE.getCpuMetric());
                jvmBuilder.addAllMemory(MemoryProvider.INSTANCE.getMemoryMetricList());
                jvmBuilder.addAllMemoryPool(MemoryPoolProvider.INSTANCE.getMemoryPoolMetricsList());
                jvmBuilder.addAllGc(GCProvider.INSTANCE.getGCList());
                jvmBuilder.setThread(ThreadProvider.INSTANCE.getThreadMetrics());
                // 设置class的指标
                jvmBuilder.setClazz(ClassProvider.INSTANCE.getClassMetrics());
    			// 将JVM的指标放在阻塞队列中
                // org.apache.skywalking.apm.agent.core.jvm.JVMMetricsSender#run方法，会将相关信息发送至oap server
                sender.offer(jvmBuilder.build());
            } catch (Exception e) { 
                LOGGER.error(e, "Collect JVM info fail.");
            }
        }

## 创建 `Source` 类 ##

public class DefaultScopeDefine { 
        public static final int SERVICE_INSTANCE_JVM_CLASS = 11000;
    
        /** Catalog of scope, the metrics processor could use this to group all generated metrics by oal rt. */
        public static final String SERVICE_INSTANCE_CATALOG_NAME = "SERVICE_INSTANCE";
    }

package org.apache.skywalking.oap.server.core.source;
    
    import lombok.Getter;
    import lombok.Setter;
    
    import static org.apache.skywalking.oap.server.core.source.DefaultScopeDefine.SERVICE_INSTANCE_CATALOG_NAME;
    import static org.apache.skywalking.oap.server.core.source.DefaultScopeDefine.SERVICE_INSTANCE_JVM_CLASS;
    
    @ScopeDeclaration(id = SERVICE_INSTANCE_JVM_CLASS, name = "ServiceInstanceJVMClass", catalog = SERVICE_INSTANCE_CATALOG_NAME)
    @ScopeDefaultColumn.VirtualColumnDefinition(fieldName = "entityId", columnName = "entity_id", isID = true, type = String.class)
    public class ServiceInstanceJVMClass extends Source { 
        @Override
        public int scope() { 
            return SERVICE_INSTANCE_JVM_CLASS;
        }
    
        @Override
        public String getEntityId() { 
            return String.valueOf(id);
        }
    
        @Getter @Setter
        private String id;
        @Getter @Setter @ScopeDefaultColumn.DefinedByField(columnName = "name", requireDynamicActive = true)
        private String name;
        @Getter @Setter @ScopeDefaultColumn.DefinedByField(columnName = "service_name", requireDynamicActive = true)
        private String serviceName;
        @Getter @Setter @ScopeDefaultColumn.DefinedByField(columnName = "service_id")
        private String serviceId;
        @Getter @Setter
        private long loadedClassCount;
        @Getter @Setter
        private long unloadedClassCount;
        @Getter @Setter
        private long totalLoadedClassCount;
    }

## 将从 `agent` 获取到的信息，发送至 `SourceReceive` ##

在 `org.apache.skywalking.oap.server.analyzer.provider.jvm.JVMSourceDispatcher` 进行如下修改

public void sendMetric(String service, String serviceInstance, JVMMetric metrics) { 
            long minuteTimeBucket = TimeBucket.getMinuteTimeBucket(metrics.getTime());
    
            final String serviceId = IDManager.ServiceID.buildId(service, NodeType.Normal);
            final String serviceInstanceId = IDManager.ServiceInstanceID.buildId(serviceId, serviceInstance);
    
            this.sendToCpuMetricProcess(
                service, serviceId, serviceInstance, serviceInstanceId, minuteTimeBucket, metrics.getCpu());
            this.sendToMemoryMetricProcess(
                service, serviceId, serviceInstance, serviceInstanceId, minuteTimeBucket, metrics.getMemoryList());
            this.sendToMemoryPoolMetricProcess(
                service, serviceId, serviceInstance, serviceInstanceId, minuteTimeBucket, metrics.getMemoryPoolList());
            this.sendToGCMetricProcess(
                service, serviceId, serviceInstance, serviceInstanceId, minuteTimeBucket, metrics.getGcList());
            this.sendToThreadMetricProcess(
                    service, serviceId, serviceInstance, serviceInstanceId, minuteTimeBucket, metrics.getThread());
            // class指标处理
            this.sendToClassMetricProcess(
                    service, serviceId, serviceInstance, serviceInstanceId, minuteTimeBucket, metrics.getClazz());
        }
    
        private void sendToClassMetricProcess(String service,
                String serviceId,
                String serviceInstance,
                String serviceInstanceId,
                long timeBucket,
                Class clazz) { 
            // 拼装Source对象
            ServiceInstanceJVMClass serviceInstanceJVMClass = new ServiceInstanceJVMClass();
            serviceInstanceJVMClass.setId(serviceInstanceId);
            serviceInstanceJVMClass.setName(serviceInstance);
            serviceInstanceJVMClass.setServiceId(serviceId);
            serviceInstanceJVMClass.setServiceName(service);
            serviceInstanceJVMClass.setLoadedClassCount(clazz.getLoadedClassCount());
            serviceInstanceJVMClass.setUnloadedClassCount(clazz.getUnloadedClassCount());
            serviceInstanceJVMClass.setTotalLoadedClassCount(clazz.getTotalLoadedClassCount());
            serviceInstanceJVMClass.setTimeBucket(timeBucket);
            // 将Source对象发送至SourceReceive进行处理
            sourceReceiver.receive(serviceInstanceJVMClass);
        }

## 在 `OAL` 词法定义和语法定义中加入 `Source` 相关信息 ##

在 `oap-server/oal-grammar/src/main/antlr4/org/apache/skywalking/oal/rt/grammar/OALLexer.g4` 定义 `Class` 关键字

// Keywords
    
    FROM: 'from';
    FILTER: 'filter';
    DISABLE: 'disable';
    SRC_ALL: 'All';
    SRC_SERVICE: 'Service';
    SRC_SERVICE_INSTANCE: 'ServiceInstance';
    SRC_ENDPOINT: 'Endpoint';
    SRC_SERVICE_RELATION: 'ServiceRelation';
    SRC_SERVICE_INSTANCE_RELATION: 'ServiceInstanceRelation';
    SRC_ENDPOINT_RELATION: 'EndpointRelation';
    SRC_SERVICE_INSTANCE_JVM_CPU: 'ServiceInstanceJVMCPU';
    SRC_SERVICE_INSTANCE_JVM_MEMORY: 'ServiceInstanceJVMMemory';
    SRC_SERVICE_INSTANCE_JVM_MEMORY_POOL: 'ServiceInstanceJVMMemoryPool';
    SRC_SERVICE_INSTANCE_JVM_GC: 'ServiceInstanceJVMGC';
    SRC_SERVICE_INSTANCE_JVM_THREAD: 'ServiceInstanceJVMThread';
    SRC_SERVICE_INSTANCE_JVM_CLASS:'ServiceInstanceJVMClass'; // 在OAL词法定义中添加Class的关键字
    SRC_DATABASE_ACCESS: 'DatabaseAccess';
    SRC_SERVICE_INSTANCE_CLR_CPU: 'ServiceInstanceCLRCPU';
    SRC_SERVICE_INSTANCE_CLR_GC: 'ServiceInstanceCLRGC';
    SRC_SERVICE_INSTANCE_CLR_THREAD: 'ServiceInstanceCLRThread';
    SRC_ENVOY_INSTANCE_METRIC: 'EnvoyInstanceMetric';

在 `oap-server/oal-grammar/src/main/antlr4/org/apache/skywalking/oal/rt/grammar/OALParser.g4` 添加 `Class` 关键字

在 `oap-server/oal-grammar` 目录下执行 `mvn clean package -DskipTests=true` 会生成新的相关 `Java` 类

## 定义 `OAL` 指标 ##

在 `oap-server/server-bootstrap/src/main/resources/oal/java-agent.oal` 中添加基于 `OAL` 语法的 `Class` 相关指标定义

// 当前加载类的数量
    instance_jvm_class_loaded_class_count = from(ServiceInstanceJVMClass.loadedClassCount).longAvg();
    // 已卸载类的数量
    instance_jvm_class_unloaded_class_count = from(ServiceInstanceJVMClass.unloadedClassCount).longAvg();
    // 一共加载类的数量
    instance_jvm_class_total_loaded_class_count = from(ServiceInstanceJVMClass.totalLoadedClassCount).longAvg();

## 配置 `UI` 面板 ##

将如下界面配置导入 `APM` 面板中

{ 
      "name": "Instance",
      "children": [{ 
          "width": "3",
          "title": "Service Instance Load",
          "height": "250",
          "entityType": "ServiceInstance",
          "independentSelector": false,
          "metricType": "REGULAR_VALUE",
          "metricName": "service_instance_cpm",
          "queryMetricType": "readMetricsValues",
          "chartType": "ChartLine",
          "unit": "CPM - calls per minute"
        },
        { 
          "width": 3,
          "title": "Service Instance Throughput",
          "height": "250",
          "entityType": "ServiceInstance",
          "independentSelector": false,
          "metricType": "REGULAR_VALUE",
          "metricName": "service_instance_throughput_received,service_instance_throughput_sent",
          "queryMetricType": "readMetricsValues",
          "chartType": "ChartLine",
          "unit": "Bytes"
        },
        { 
          "width": "3",
          "title": "Service Instance Successful Rate",
          "height": "250",
          "entityType": "ServiceInstance",
          "independentSelector": false,
          "metricType": "REGULAR_VALUE",
          "metricName": "service_instance_sla",
          "queryMetricType": "readMetricsValues",
          "chartType": "ChartLine",
          "unit": "%",
          "aggregation": "/",
          "aggregationNum": "100"
        },
        { 
          "width": "3",
          "title": "Service Instance Latency",
          "height": "250",
          "entityType": "ServiceInstance",
          "independentSelector": false,
          "metricType": "REGULAR_VALUE",
          "metricName": "service_instance_resp_time",
          "queryMetricType": "readMetricsValues",
          "chartType": "ChartLine",
          "unit": "ms"
        },
        { 
          "width": 3,
          "title": "JVM CPU (Java Service)",
          "height": "250",
          "entityType": "ServiceInstance",
          "independentSelector": false,
          "metricType": "REGULAR_VALUE",
          "metricName": "instance_jvm_cpu",
          "queryMetricType": "readMetricsValues",
          "chartType": "ChartLine",
          "unit": "%",
          "aggregation": "+",
          "aggregationNum": ""
        },
        { 
          "width": 3,
          "title": "JVM Memory (Java Service)",
          "height": "250",
          "entityType": "ServiceInstance",
          "independentSelector": false,
          "metricType": "REGULAR_VALUE",
          "metricName": "instance_jvm_memory_heap, instance_jvm_memory_heap_max,instance_jvm_memory_noheap, instance_jvm_memory_noheap_max",
          "queryMetricType": "readMetricsValues",
          "chartType": "ChartLine",
          "unit": "MB",
          "aggregation": "/",
          "aggregationNum": "1048576"
        },
        { 
          "width": 3,
          "title": "JVM GC Time",
          "height": "250",
          "entityType": "ServiceInstance",
          "independentSelector": false,
          "metricType": "REGULAR_VALUE",
          "metricName": "instance_jvm_young_gc_time, instance_jvm_old_gc_time",
          "queryMetricType": "readMetricsValues",
          "chartType": "ChartLine",
          "unit": "ms"
        },
        { 
          "width": 3,
          "title": "JVM GC Count",
          "height": "250",
          "entityType": "ServiceInstance",
          "independentSelector": false,
          "metricType": "REGULAR_VALUE",
          "queryMetricType": "readMetricsValues",
          "chartType": "ChartBar",
          "metricName": "instance_jvm_young_gc_count, instance_jvm_old_gc_count"
        },
        { 
          "width": 3,
          "title": "JVM Thread Count (Java Service)",
          "height": "250",
          "entityType": "ServiceInstance",
          "independentSelector": false,
          "metricType": "REGULAR_VALUE",
          "queryMetricType": "readMetricsValues",
          "chartType": "ChartLine",
          "metricName": "instance_jvm_thread_live_count, instance_jvm_thread_daemon_count, instance_jvm_thread_peak_count,instance_jvm_thread_deadlocked,instance_jvm_thread_monitor_deadlocked"
        },
        { 
          "width": 3,
          "title": "JVM Thread State Count (Java Service)",
          "height": "250",
          "entityType": "ServiceInstance",
          "independentSelector": false,
          "metricType": "REGULAR_VALUE",
          "metricName": "instance_jvm_thread_new_thread_count,instance_jvm_thread_runnable_thread_count,instance_jvm_thread_blocked_thread_count,instance_jvm_thread_wait_thread_count,instance_jvm_thread_time_wait_thread_count,instance_jvm_thread_terminated_thread_count",
          "queryMetricType": "readMetricsValues",
          "chartType": "ChartBar"
        },
        { 
          "width": 3,
          "title": "JVM Class Count (Java Service)",
          "height": "250",
          "entityType": "ServiceInstance",
          "independentSelector": false,
          "metricType": "REGULAR_VALUE",
          "metricName": "instance_jvm_class_loaded_class_count,instance_jvm_class_unloaded_class_count,instance_jvm_class_total_loaded_class_count",
          "queryMetricType": "readMetricsValues",
          "chartType": "ChartArea"
        },
        { 
          "width": 3,
          "title": "CLR CPU (.NET Service)",
          "height": "250",
          "entityType": "ServiceInstance",
          "independentSelector": false,
          "metricType": "REGULAR_VALUE",
          "metricName": "instance_clr_cpu",
          "queryMetricType": "readMetricsValues",
          "chartType": "ChartLine",
          "unit": "%"
        },
        { 
          "width": 3,
          "title": "CLR GC (.NET Service)",
          "height": "250",
          "entityType": "ServiceInstance",
          "independentSelector": false,
          "metricType": "REGULAR_VALUE",
          "metricName": "instance_clr_gen0_collect_count, instance_clr_gen1_collect_count, instance_clr_gen2_collect_count",
          "queryMetricType": "readMetricsValues",
          "chartType": "ChartBar"
        },
        { 
          "width": 3,
          "title": "CLR Heap Memory (.NET Service)",
          "height": "250",
          "entityType": "ServiceInstance",
          "independentSelector": false,
          "metricType": "REGULAR_VALUE",
          "metricName": "instance_clr_heap_memory",
          "queryMetricType": "readMetricsValues",
          "chartType": "ChartLine",
          "unit": "MB",
          "aggregation": "/",
          "aggregationNum": "1048576"
        },
        { 
          "width": 3,
          "title": "CLR Thread (.NET Service)",
          "height": "250",
          "entityType": "ServiceInstance",
          "independentSelector": false,
          "metricType": "REGULAR_VALUE",
          "queryMetricType": "readMetricsValues",
          "chartType": "ChartLine",
          "metricName": "instance_clr_available_completion_port_threads,instance_clr_available_worker_threads,instance_clr_max_completion_port_threads,instance_clr_max_worker_threads"
        }
      ]
    }

## 结果校验 ##

可以看到导入的界面中，已经有 `Class` 相关指标了

![file][file 1]

# 代码贡献 #

*  [Add some new thread metric and class metric to JVMMetric \#7230][Add some new thread metric and class metric to JVMMetric _7230]
 *  [add some new thread metric and class metric to JVMMetric \#52][add some new thread metric and class metric to JVMMetric _52]
 *  [Remove Terminated State and New State in JVMMetric (\#7230) \#53][Remove Terminated State and New State in JVMMetric _7230_ _53]
 *  [Add some new thread metric and class metric to JVMMetric (\#7230) \#7243][Add some new thread metric and class metric to JVMMetric _7230_ _7243]

# 参考文档 #

*  [Observability Analysis Language][]
 *  [Source and Scope extension for new metrics][]
 *  [Java ManagementFactory解析][Java ManagementFactory]

[Observability Analysis Language]: https://skywalking.apache.org/docs/main/v8.4.0/en/concepts-and-designs/oal/
[file]: /images/20220829/ef7671ba1b314c138fa864734f5b9d9b.png
[Skywalking-04_Metric]: https://switch.blog.csdn.net/article/details/119191293
[Source and Scope extension for new metrics]: https://skywalking.apache.org/docs/main/v8.4.0/en/guides/source-extension/
[Java ManagementFactory]: https://www.jianshu.com/p/5d854245051d
[file 1]: /images/20220829/e1d76c3f29d1487cbceea2733ecbb73b.png
[Add some new thread metric and class metric to JVMMetric _7230]: https://github.com/apache/skywalking/issues/7230
[add some new thread metric and class metric to JVMMetric _52]: https://github.com/apache/skywalking-data-collect-protocol/pull/52
[Remove Terminated State and New State in JVMMetric _7230_ _53]: https://github.com/apache/skywalking-data-collect-protocol/pull/53
[Add some new thread metric and class metric to JVMMetric _7230_ _7243]: https://github.com/apache/skywalking/pull/7243