目前Java web应用中大规模使用分布式系统和集群，集群中存在多台服务器对外提供服务，那么就存在一个问题，如何确定一个请求应该分发到哪台服务器上呢，这就需要获取当前服务器CPU、内存、网络、文件句柄的使用情况，合理分发请求，以使集群中所有服务器达到负载均衡的效果。
获取CPU利用率
通过使用java.lang.Runtime类执行cat /proc/stat命令获取Cpu时钟数据，进行Cpu利用率计算。“proc文件系统是一个伪文件系统，它只存在内存当中，而不占用外存空间。它以文件系统的方式为访问系统内核数据的操作提供接口。用户和应用程序可以通过proc得到系统的信息，并可以改变内核的某些参数。” 因此，程序在从/proc/stat中获取Cpu指标时，不会发生磁盘I/O，计算Cpu使用率的实时性更强，计算结果更可靠。[
参数解释]
参考地址：
http://blog.csdn.net/blue_jjw/article/details/8741000
代码实现
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
| package com.oracle.jvm.load;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
* @auth zhengzhi.ren
* @date 2015/7/25.
*/
public class CpuMonitor {
private static final String IDLE_TIME = "idleTime";
private static final String TOTAL_TIME = "totalTime";
private static final String command = "cat /proc/stat";
private Long intervalSecond = 60L;
public Map<String, Long> process() throws IOException {
System.out.println("Start to collect usage of cpu.");
Process process = null;
BufferedReader reader = null;
Map<String, Long> cpuLoad = new ConcurrentHashMap<String, Long>(1);
try {
Runtime runtime = Runtime.getRuntime();
process = runtime.exec(command);
reader = new BufferedReader(new InputStreamReader(process.getInputStream()));
Long idleTime = 0L;
Long totalCpuTime = 0L;
String data = null;
String[] load = null;
while ((data = reader.readLine()) != null) {
if (!data.startsWith("cpu")) {
continue;
}
data = data.trim();
System.out.println("The current information of cpu:" + data);
load = data.split("\\s+");
idleTime = Long.parseLong(load[4]);
for (String info : load) {
if ("cpu".equals(info)){
continue;
}
totalCpuTime += Long.parseLong(info);
}
break;
}
cpuLoad.put(IDLE_TIME, idleTime);
cpuLoad.put(TOTAL_TIME, totalCpuTime);
} finally {
reader.close();
process.destroy();
}
System.out.println("Collect usage of cpu end.");
return cpuLoad;
}
* compute usage rate of cpu
* @return
*/
public double getCpuUsageRate() throws IOException, InterruptedException {
Map<String, Long> firesClock = process();
Thread.sleep(intervalSecond);
Map<String, Long> lastClock = process();
Long firstIdleTime = firesClock.get(IDLE_TIME);
Long lastIdleTime = lastClock.get(TOTAL_TIME);
Long firstTotalTime = firesClock.get(IDLE_TIME);
Long lastTotalTime = lastClock.get(TOTAL_TIME);
return 1 - (float)(lastIdleTime - firstIdleTime)/(float)(lastTotalTime - firstTotalTime);
}
}
|