聊聊dubbo的StatusChecker

序

本文主要研究一下dubbo的StatusChecker

Status

dubbo-2.7.2/dubbo-common/src/main/java/org/apache/dubbo/common/status/Status.java

public class Status {    private final Level level;    private final String message;    private final String description;    public Status(Level level) {        this(level, null, null);    }    public Status(Level level, String message) {        this(level, message, null);    }    public Status(Level level, String message, String description) {        this.level = level;        this.message = message;        this.description = description;    }    public Level getLevel() {        return level;    }    public String getMessage() {        return message;    }    public String getDescription() {        return description;    }    /**     * Level     */    public enum Level {        /**         * OK         */        OK,        /**         * WARN         */        WARN,        /**         * ERROR         */        ERROR,        /**         * UNKNOWN         */        UNKNOWN    }}

• Status定义了三个属性，分别是level、message、description；其中level有OK、WARN、ERROR、UNKNOWN四个级别

StatusChecker

dubbo-2.7.2/dubbo-common/src/main/java/org/apache/dubbo/common/status/StatusChecker.java

@SPIpublic interface StatusChecker {    /**     * check status     *     * @return status     */    Status check();}

• StatusChecker定义了check接口，返回Status

LoadStatusChecker

dubbo-2.7.2/dubbo-common/src/main/java/org/apache/dubbo/common/status/support/LoadStatusChecker.java

@Activatepublic class LoadStatusChecker implements StatusChecker {    @Override    public Status check() {        OperatingSystemMXBean operatingSystemMXBean = ManagementFactory.getOperatingSystemMXBean();        double load;        try {            Method method = OperatingSystemMXBean.class.getMethod("getSystemLoadAverage", new Class<?>[0]);            load = (Double) method.invoke(operatingSystemMXBean, new Object[0]);            if (load == -1) {                com.sun.management.OperatingSystemMXBean bean =                        (com.sun.management.OperatingSystemMXBean) operatingSystemMXBean;                load = bean.getSystemCpuLoad();            }        } catch (Throwable e) {            load = -1;        }        int cpu = operatingSystemMXBean.getAvailableProcessors();        return new Status(load < 0 ? Status.Level.UNKNOWN : (load < cpu ? Status.Level.OK : Status.Level.WARN),                (load < 0 ? "" : "load:" + load + ",") + "cpu:" + cpu);    }}

• LoadStatusChecker实现了StatusChecker接口，其check方法从operatingSystemMXBean的getSystemLoadAverage方法读取load，然后根据cpu个数来计算load

MemoryStatusChecker

dubbo-2.7.2/dubbo-common/src/main/java/org/apache/dubbo/common/status/support/MemoryStatusChecker.java

@Activatepublic class MemoryStatusChecker implements StatusChecker {    @Override    public Status check() {        Runtime runtime = Runtime.getRuntime();        long freeMemory = runtime.freeMemory();        long totalMemory = runtime.totalMemory();        long maxMemory = runtime.maxMemory();        boolean ok = (maxMemory - (totalMemory - freeMemory) > 2048); // Alarm when spare memory < 2M        String msg = "max:" + (maxMemory / 1024 / 1024) + "M,total:"                + (totalMemory / 1024 / 1024) + "M,used:" + ((totalMemory / 1024 / 1024) - (freeMemory / 1024 / 1024)) + "M,free:" + (freeMemory / 1024 / 1024) + "M";        return new Status(ok ? Status.Level.OK : Status.Level.WARN, msg);    }}

• MemoryStatusChecker实现了实现了StatusChecker接口，其check方法从Runtime获取freeMemory、totalMemory、maxMemory，当maxMemory - (totalMemory - freeMemory) > 2048返回OK，否则返回WARN

小结

• StatusChecker定义了check接口，返回Status；Status定义了三个属性，分别是level、message、description；其中level有OK、WARN、ERROR、UNKNOWN四个级别
• LoadStatusChecker实现了StatusChecker接口，其check方法从operatingSystemMXBean的getSystemLoadAverage方法读取load，然后根据cpu个数来计算load
• MemoryStatusChecker实现了实现了StatusChecker接口，其check方法从Runtime获取freeMemory、totalMemory、maxMemory，当maxMemory - (totalMemory - freeMemory) > 2048返回OK，否则返回WARN

doc

• StatusChecker
• LoadStatusChecker
• MemoryStatusChecker