聊聊Elasticsearch的ProcessProbe

序

本文主要研究一下Elasticsearch的ProcessProbe

ProcessProbe

elasticsearch-7.0.1/server/src/main/java/org/elasticsearch/monitor/process/ProcessProbe.java

public class ProcessProbe {    private static final OperatingSystemMXBean osMxBean = ManagementFactory.getOperatingSystemMXBean();    private static final Method getMaxFileDescriptorCountField;    private static final Method getOpenFileDescriptorCountField;    private static final Method getProcessCpuLoad;    private static final Method getProcessCpuTime;    private static final Method getCommittedVirtualMemorySize;    static {        getMaxFileDescriptorCountField = getUnixMethod("getMaxFileDescriptorCount");        getOpenFileDescriptorCountField = getUnixMethod("getOpenFileDescriptorCount");        getProcessCpuLoad = getMethod("getProcessCpuLoad");        getProcessCpuTime = getMethod("getProcessCpuTime");        getCommittedVirtualMemorySize = getMethod("getCommittedVirtualMemorySize");    }    private static class ProcessProbeHolder {        private static final ProcessProbe INSTANCE = new ProcessProbe();    }    public static ProcessProbe getInstance() {        return ProcessProbeHolder.INSTANCE;    }    private ProcessProbe() {    }    /**     * Returns the maximum number of file descriptors allowed on the system, or -1 if not supported.     */    public long getMaxFileDescriptorCount() {        if (getMaxFileDescriptorCountField == null) {            return -1;        }        try {            return (Long) getMaxFileDescriptorCountField.invoke(osMxBean);        } catch (Exception t) {            return -1;        }    }    /**     * Returns the number of opened file descriptors associated with the current process, or -1 if not supported.     */    public long getOpenFileDescriptorCount() {        if (getOpenFileDescriptorCountField == null) {            return -1;        }        try {            return (Long) getOpenFileDescriptorCountField.invoke(osMxBean);        } catch (Exception t) {            return -1;        }    }    /**     * Returns the process CPU usage in percent     */    public short getProcessCpuPercent() {        return Probes.getLoadAndScaleToPercent(getProcessCpuLoad, osMxBean);    }    /**     * Returns the CPU time (in milliseconds) used by the process on which the Java virtual machine is running, or -1 if not supported.     */    public long getProcessCpuTotalTime() {        if (getProcessCpuTime != null) {            try {                long time = (long) getProcessCpuTime.invoke(osMxBean);                if (time >= 0) {                    return (time / 1_000_000L);                }            } catch (Exception t) {                return -1;            }        }        return -1;    }    /**     * Returns the size (in bytes) of virtual memory that is guaranteed to be available to the running process     */    public long getTotalVirtualMemorySize() {        if (getCommittedVirtualMemorySize != null) {            try {                long virtual = (long) getCommittedVirtualMemorySize.invoke(osMxBean);                if (virtual >= 0) {                    return virtual;                }            } catch (Exception t) {                return -1;            }        }        return -1;    }    public ProcessInfo processInfo(long refreshInterval) {        return new ProcessInfo(jvmInfo().pid(), BootstrapInfo.isMemoryLocked(), refreshInterval);    }    public ProcessStats processStats() {        ProcessStats.Cpu cpu = new ProcessStats.Cpu(getProcessCpuPercent(), getProcessCpuTotalTime());        ProcessStats.Mem mem = new ProcessStats.Mem(getTotalVirtualMemorySize());        return new ProcessStats(System.currentTimeMillis(), getOpenFileDescriptorCount(), getMaxFileDescriptorCount(), cpu, mem);    }    /**     * Returns a given method of the OperatingSystemMXBean,     * or null if the method is not found or unavailable.     */    private static Method getMethod(String methodName) {        try {            return Class.forName("com.sun.management.OperatingSystemMXBean").getMethod(methodName);        } catch (Exception t) {            // not available            return null;        }    }    /**     * Returns a given method of the UnixOperatingSystemMXBean,     * or null if the method is not found or unavailable.     */    private static Method getUnixMethod(String methodName) {        try {            return Class.forName("com.sun.management.UnixOperatingSystemMXBean").getMethod(methodName);        } catch (Exception t) {            // not available            return null;        }    }}

• ProcessProbe使用static代码块反射获取了getMaxFileDescriptorCountField、getOpenFileDescriptorCountField、getProcessCpuLoad、getProcessCpuTime、getCommittedVirtualMemorySize这几个method
• getMaxFileDescriptorCountField、getOpenFileDescriptorCountField使用getUnixMethod方法，从com.sun.management.UnixOperatingSystemMXBean获取
• getProcessCpuLoad、getProcessCpuTime、getCommittedVirtualMemorySize使用getMethod方法，从com.sun.management.OperatingSystemMXBean获取
• getMaxFileDescriptorCount、getOpenFileDescriptorCount、getProcessCpuTotalTime、getTotalVirtualMemorySize方法首先都判断对应的method是否为null，如果为null则返回-1，否则则反射获取对应的值，出现异常的话，返回-1
• processStats方法返回ProcessStats，它由ProcessStats.Cpu、ProcessStats.Mem、getOpenFileDescriptorCount()、getMaxFileDescriptorCount()构成

小结

• ProcessProbe使用static代码块反射获取了getMaxFileDescriptorCountField、getOpenFileDescriptorCountField、getProcessCpuLoad、getProcessCpuTime、getCommittedVirtualMemorySize这几个method
• getMaxFileDescriptorCount、getOpenFileDescriptorCount、getProcessCpuTotalTime、getTotalVirtualMemorySize方法首先都判断对应的method是否为null，如果为null则返回-1，否则则反射获取对应的值，出现异常的话，返回-1
• processStats方法返回ProcessStats，它由ProcessStats.Cpu、ProcessStats.Mem、getOpenFileDescriptorCount()、getMaxFileDescriptorCount()构成

doc

• ProcessProbe