jconsole的进程概览选项卡显示了CPU使用百分比。是否有一个MBean可以提供这个值?它的ObjectName是什么?
更新:在Java 7中,您可以像这样实现:
public static double getProcessCpuLoad() throws MalformedObjectNameException, ReflectionException, InstanceNotFoundException {
MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
ObjectName name = ObjectName.getInstance("java.lang:type=OperatingSystem");
AttributeList list = mbs.getAttributes(name, new String[]{ "ProcessCpuLoad" });
if (list.isEmpty()) return Double.NaN;
Attribute att = (Attribute)list.get(0);
Double value = (Double)att.getValue();
if (value == -1.0) return Double.NaN;
return ((int)(value * 1000) / 10.0); // returns a percentage value with 1 decimal point precision
}
在Java 7中,您可以使用com.sun.management.OperatingSystemMXBean
的隐藏方法:
getProcessCpuLoad() // returns the CPU usage of the JVM
getSystemCpuLoad() // returns the CPU usage of the whole system
这两个值都以介于0.0和1.0之间的double形式返回,因此只需将其乘以100即可获得百分比。
com.sun.management.OperatingSystemMXBean osBean = ManagementFactory.getPlatformMXBean(OperatingSystemMXBean.class);
System.out.println(osBean.getProcessCpuLoad() * 100);
System.out.println(osBean.getSystemCpuLoad() * 100);
由于这些方法被隐藏且未记录在java.lang.management.OperatingSystemMXBean
中,而是存在于 com.sun.management.OperatingSystemMXBean
包中,因此有可能在某些JVM或将来的更新中无法使用,所以您需要决定是否愿意承担这个风险。
在ManagementFactory中似乎没有直接的MBean。最接近的是OperatingSystemMXBean,它可以用于计算整个系统使用的CPU。
然而,这个网址提出了一种方法,基于jconsole的源代码。
com.sun.management.OperatingSystemMXBean
在Java 6中不可访问... - Matthieupublic float getCpuUsed() {
/** get a MXBean */
com.sun.management.OperatingSystemMXBean osMXBean =
(com.sun.management.OperatingSystemMXBean)
ManagementFactory.getOperatingSystemMXBean();
/** set old timestamp values */
long previousJvmProcessCpuTime = osMXBean.getProcessCpuTime();
int sleepTime = 350;
/** sleep for a while to use to calculate */
try {
TimeUnit.MILLISECONDS.sleep(sleepTime);
} catch (InterruptedException e) {
logger.error("InterruptedException occurred while MemoryCollector sleeping...");
}
/** elapsed process time is in nanoseconds */
long elapsedProcessCpuTime = osMXBean.getProcessCpuTime() - previousJvmProcessCpuTime;
/** elapsed uptime is in milliseconds */
long elapsedJvmUptime = sleepTime ;
/** total jvm uptime on all the available processors */
//long totalElapsedJvmUptime = elapsedJvmUptime * osMXBean.getAvailableProcessors() ;
long totalElapsedJvmUptime = elapsedJvmUptime;
//System.out.println("echo cpu processors num " + osMXBean.getAvailableProcessors());
/** calculate cpu usage as a percentage value
to convert nanoseconds to milliseconds divide it by 1000000 and to get a percentage multiply it by 100 */
float cpuUsage = elapsedProcessCpuTime / (totalElapsedJvmUptime * 10000F);
return (float)(Math.round(cpuUsage*10)/10);
}
final OperatingSystemMXBean mxBean = ManagementFactory.getOperatingSystemMXBean();
if (mxBean instanceof UnixOperatingSystemMXBean) {
return ((UnixOperatingSystemMXBean) mxBean).getSystemCpuLoad() * 100.0;
}
OperatingSystemMXBean::getProcessCpuLoad
不同。示例中的值大约是后者的100倍。对此有何见解? - ALEXANDER KONSTANTINOV