聊聊skywalking的JVMService

序

本文主要研究一下skywalking的JVMService

BootService

skywalking-6.6.0/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/boot/BootService.java

public interface BootService {
    void prepare() throws Throwable;

    void boot() throws Throwable;

    void onComplete() throws Throwable;

    void shutdown() throws Throwable;
}

• BootService定义了prepare、boot、onComplete、shutdown四个方法

JVMService

skywalking-6.6.0/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/jvm/JVMService.java

@DefaultImplementor
public class JVMService implements BootService, Runnable {
    private static final ILog logger = LogManager.getLogger(JVMService.class);
    private LinkedBlockingQueue<JVMMetric> queue;
    private volatile ScheduledFuture<?> collectMetricFuture;
    private volatile ScheduledFuture<?> sendMetricFuture;
    private Sender sender;

    @Override
    public void prepare() throws Throwable {
        queue = new LinkedBlockingQueue<JVMMetric>(Config.Jvm.BUFFER_SIZE);
        sender = new Sender();
        ServiceManager.INSTANCE.findService(GRPCChannelManager.class).addChannelListener(sender);
    }

    @Override
    public void boot() throws Throwable {
        collectMetricFuture = Executors
            .newSingleThreadScheduledExecutor(new DefaultNamedThreadFactory("JVMService-produce"))
            .scheduleAtFixedRate(new RunnableWithExceptionProtection(this, new RunnableWithExceptionProtection.CallbackWhenException() {
                @Override public void handle(Throwable t) {
                    logger.error("JVMService produces metrics failure.", t);
                }
            }), 0, 1, TimeUnit.SECONDS);
        sendMetricFuture = Executors
            .newSingleThreadScheduledExecutor(new DefaultNamedThreadFactory("JVMService-consume"))
            .scheduleAtFixedRate(new RunnableWithExceptionProtection(sender, new RunnableWithExceptionProtection.CallbackWhenException() {
                @Override public void handle(Throwable t) {
                    logger.error("JVMService consumes and upload failure.", t);
                }
            }
            ), 0, 1, TimeUnit.SECONDS);
    }

    @Override
    public void onComplete() throws Throwable {

    }

    @Override
    public void shutdown() throws Throwable {
        collectMetricFuture.cancel(true);
        sendMetricFuture.cancel(true);
    }

    @Override
    public void run() {
        if (RemoteDownstreamConfig.Agent.SERVICE_ID != DictionaryUtil.nullValue()
            && RemoteDownstreamConfig.Agent.SERVICE_INSTANCE_ID != DictionaryUtil.nullValue()
        ) {
            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());

                JVMMetric jvmMetric = jvmBuilder.build();
                if (!queue.offer(jvmMetric)) {
                    queue.poll();
                    queue.offer(jvmMetric);
                }
            } catch (Exception e) {
                logger.error(e, "Collect JVM info fail.");
            }
        }
    }

    //......
}

• JVMService实现了BootService及Runnable接口，其prepare方法创建了JVMMetric类型的LinkedBlockingQueue，以及Sender，并往GRPCChannelManager添加了该Sender；其boot方法注册了collectMetricFuture、sendMetricFuture两个调度任务，调度间隔都是1秒；其shutdown方法执行collectMetricFuture.cancel(true)及sendMetricFuture.cancel(true)；其run方法主要是构建JVMMetric然后添加到queue中

Sender

skywalking-6.6.0/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/jvm/JVMService.java

    private class Sender implements Runnable, GRPCChannelListener {
        private volatile GRPCChannelStatus status = GRPCChannelStatus.DISCONNECT;
        private volatile JVMMetricReportServiceGrpc.JVMMetricReportServiceBlockingStub stub = null;

        @Override
        public void run() {
            if (RemoteDownstreamConfig.Agent.SERVICE_ID != DictionaryUtil.nullValue()
                && RemoteDownstreamConfig.Agent.SERVICE_INSTANCE_ID != DictionaryUtil.nullValue()
            ) {
                if (status == GRPCChannelStatus.CONNECTED) {
                    try {
                        JVMMetricCollection.Builder builder = JVMMetricCollection.newBuilder();
                        LinkedList<JVMMetric> buffer = new LinkedList<JVMMetric>();
                        queue.drainTo(buffer);
                        if (buffer.size() > 0) {
                            builder.addAllMetrics(buffer);
                            builder.setServiceInstanceId(RemoteDownstreamConfig.Agent.SERVICE_INSTANCE_ID);
                            Commands commands = stub.withDeadlineAfter(GRPC_UPSTREAM_TIMEOUT, TimeUnit.SECONDS).collect(builder.build());
                            ServiceManager.INSTANCE.findService(CommandService.class).receiveCommand(commands);
                        }
                    } catch (Throwable t) {
                        logger.error(t, "send JVM metrics to Collector fail.");
                    }
                }
            }
        }

        @Override
        public void statusChanged(GRPCChannelStatus status) {
            if (GRPCChannelStatus.CONNECTED.equals(status)) {
                Channel channel = ServiceManager.INSTANCE.findService(GRPCChannelManager.class).getChannel();
                stub = JVMMetricReportServiceGrpc.newBlockingStub(channel);
            }
            this.status = status;
        }
    }

• Sender实现了Runnable, GRPCChannelListener接口，其run方法在status为GRPCChannelStatus.CONNECTED时执行queue.drainTo(buffer)，在buffer不为空时构造commands，然后通过ServiceManager.INSTANCE.findService(CommandService.class).receiveCommand(commands)发送JVMMetric；statusChanged方法会设置status，并在GRPCChannelStatus.CONNECTED.equals(status)时通过JVMMetricReportServiceGrpc.newBlockingStub(channel)设置stub

RunnableWithExceptionProtection

skywalking-6.6.0/apm-commons/apm-util/src/main/java/org/apache/skywalking/apm/util/RunnableWithExceptionProtection.java

public class RunnableWithExceptionProtection implements Runnable {
    private Runnable run;
    private CallbackWhenException callback;

    public RunnableWithExceptionProtection(Runnable run, CallbackWhenException callback) {
        this.run = run;
        this.callback = callback;
    }

    @Override
    public void run() {
        try {
            run.run();
        } catch (Throwable t) {
            callback.handle(t);
        }
    }

    public interface CallbackWhenException {
        void handle(Throwable t);
    }
}

• RunnableWithExceptionProtection实现了Runnable接口，其构造器要求Runnable及CallbackWhenException参数，其run方法会catch住run.run()的Throwable异常，然后回调CallbackWhenException的handle方法

小结

JVMService实现了BootService及Runnable接口，其prepare方法创建了JVMMetric类型的LinkedBlockingQueue，以及Sender，并往GRPCChannelManager添加了该Sender；其boot方法注册了collectMetricFuture、sendMetricFuture两个调度任务，调度间隔都是1秒；其shutdown方法执行collectMetricFuture.cancel(true)及sendMetricFuture.cancel(true)；其run方法主要是构建JVMMetric然后添加到queue中

doc

• JVMService