Get OS-level system information

Question

I m currently building a Java app that could end up being run on many different platforms  but primarily variants of Solaris  Linux and Windows   Has anyone been able to successfully extract information such as the current disk space used  CPU utilisation and memory used in the underlying OS  What about just what the Java app itself is consuming   Preferrably I d like to get this information without using JNI

User · Answer

If you are using Jrockit VM then here is an other way of getting VM CPU usage  Runtime bean can also give you CPU load per processor  I have used this only on Red Hat Linux to observer Tomcat performance  You have to enable JMX remote in catalina sh for this to work   JMXServiceURL url   new JMXServiceURL  service jmx rmi    jndi rmi   my tomcat host 8080 jmxrmi    JMXConnector jmxc   JMXConnectorFactory connect url  null        MBeanServerConnection conn   jmxc getMBeanServerConnection           ObjectName name   new ObjectName  oracle jrockit management type Runtime    Double jvmCpuLoad   Double conn getAttribute name   VMGeneratedCPULoad

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CPU usage isn t straightforward -- java lang management via com sun management OperatingSystemMXBean getProcessCpuTime comes close  see Patrick s excellent code snippet above  but note that it only gives access to time the CPU spent in your process   it won t tell you about CPU time spent in other processes  or even CPU time spent doing system activities related to your process   for instance i have a network-intensive java process -- it s the only thing running and the CPU is at 99  but only 55  of that is reported as  processor CPU    don t even get me started on  load average  as it s next to useless  despite being the only cpu-related item on the MX bean   if only sun in their occasional wisdom exposed something like  getTotalCpuTime      for serious CPU monitoring SIGAR mentioned by Matt seems the best bet

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Add OSHI dependency via maven    lt dependency gt       lt groupId gt com github dblock lt  groupId gt       lt artifactId gt oshi-core lt  artifactId gt       lt version gt 2 2 lt  version gt   lt  dependency gt    Get a battery capacity left in percentage   SystemInfo si   new SystemInfo    HardwareAbstractionLayer hal   si getHardware    for  PowerSource pSource   hal getPowerSources          System out println String format   n  s     1f     pSource getName    pSource getRemainingCapacity     100d

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I think the best method out there is to implement the SIGAR API by Hyperic   It works for most of the major operating systems   darn near anything modern   and is very easy to work with   The developer s  are very responsive on their forum and mailing lists   I also like that it is GPL2 Apache licensed   They provide a ton of examples in Java too   SIGAR    System Information  Gathering And Reporting tool

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Usually  to get low level OS information you can call OS specific commands which give you the information you want with Runtime exec   or read files such as  proc   in Linux

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On Windows  you can run the systeminfo command and retrieves its output for instance with the following code   private static class WindowsSystemInformation       static String get   throws IOException               Runtime runtime   Runtime getRuntime            Process process   runtime exec  systeminfo            BufferedReader systemInformationReader   new BufferedReader new InputStreamReader process getInputStream               StringBuilder stringBuilder   new StringBuilder            String line           while   line   systemInformationReader readLine       null                        stringBuilder append line               stringBuilder append System lineSeparator                        return stringBuilder toString   trim

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One simple way which can be used to get the OS level information and I tested in my Mac which works well     OperatingSystemMXBean osBean            OperatingSystemMXBean ManagementFactory getOperatingSystemMXBean        return osBean getProcessCpuLoad      You can find many relevant metrics of the operating system here

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For windows I went this way       com sun management OperatingSystemMXBean os    com sun management OperatingSystemMXBean  ManagementFactory getOperatingSystemMXBean         long physicalMemorySize   os getTotalPhysicalMemorySize        long freePhysicalMemory   os getFreePhysicalMemorySize        long freeSwapSize   os getFreeSwapSpaceSize        long commitedVirtualMemorySize   os getCommittedVirtualMemorySize      Here is the link with details

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You can get some system-level information by using System getenv    passing the relevant environment variable name as a parameter  For example  on Windows   System getenv  PROCESSOR IDENTIFIER   System getenv  PROCESSOR ARCHITECTURE   System getenv  PROCESSOR ARCHITEW6432   System getenv  NUMBER OF PROCESSORS     For other operating systems the presence absence and names of the relevant environment variables will differ

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It is still under development but you can already use jHardware   It is a simple library that scraps system data using Java  It works in both Linux and Windows   ProcessorInfo info   HardwareInfo getProcessorInfo      Get named info System out println  Cache size      info getCacheSize             System out println  Family      info getFamily     System out println  Speed  Mhz       info getMhz

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The java lang management package does give you a whole lot more info than Runtime - for example it will give you heap memory  ManagementFactory getMemoryMXBean   getHeapMemoryUsage    separate from non-heap memory  ManagementFactory getMemoryMXBean   getNonHeapMemoryUsage      You can also get process CPU usage  without writing your own JNI code   but you need to cast the java lang management OperatingSystemMXBean to a com sun management OperatingSystemMXBean  This works on Windows and Linux  I haven t tested it elsewhere   For example     call the get getCpuUsage   method more frequently to get more accurate readings   public class PerformanceMonitor        private int  availableProcessors   getOperatingSystemMXBean   getAvailableProcessors        private long lastSystemTime        0      private long lastProcessCpuTime    0       public synchronized double getCpuUsage                 if   lastSystemTime    0                         baselineCounters                return                     long systemTime       System nanoTime            long processCpuTime   0           if   getOperatingSystemMXBean   instanceof OperatingSystemMXBean                         processCpuTime      OperatingSystemMXBean  getOperatingSystemMXBean     getProcessCpuTime                       double cpuUsage    double    processCpuTime - lastProcessCpuTime       systemTime - lastSystemTime             lastSystemTime       systemTime          lastProcessCpuTime   processCpuTime           return cpuUsage   availableProcessors             private void baselineCounters                 lastSystemTime   System nanoTime             if   getOperatingSystemMXBean   instanceof OperatingSystemMXBean                         lastProcessCpuTime      OperatingSystemMXBean  getOperatingSystemMXBean     getProcessCpuTime

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To get the System Load average of 1 minute  5 minutes and 15 minutes inside the java code  you can do this by executing the command cat  proc loadavg using and interpreting it as below       Runtime runtime   Runtime getRuntime         BufferedReader br   new BufferedReader          new InputStreamReader runtime exec  cat  proc loadavg   getInputStream           String avgLine   br readLine        System out println avgLine       List lt String gt  avgLineList   Arrays asList avgLine split    s          System out println avgLineList       System out println  Average load 1 minute       avgLineList get 0        System out println  Average load 5 minutes       avgLineList get 1        System out println  Average load 15 minutes       avgLineList get 2      And to get the physical system memory by executing the command free -m and then interpreting it as below   Runtime runtime   Runtime getRuntime     BufferedReader br   new BufferedReader      new InputStreamReader runtime exec  free -m   getInputStream       String line  String memLine       int index   0  while   line   br readLine       null      if  index    1        memLine   line        index                          total        used        free      shared  buff cache   available       Mem           15933        3153        9683         310        3097       12148       Swap           3814           0        3814  List lt String gt  memInfoList   Arrays asList memLine split    s      int totalSystemMemory   Integer parseInt memInfoList get 1    int totalSystemUsedMemory   Integer parseInt memInfoList get 2    int totalSystemFreeMemory   Integer parseInt memInfoList get 3     System out println  Total system memory in mb      totalSystemMemory   System out println  Total system used memory in mb      totalSystemUsedMemory   System out println  Total system free memory in mb        totalSystemFreeMemory

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There s a Java project that uses JNA  so no native libraries to install  and is in active development  It currently supports Linux  OSX  Windows  Solaris and FreeBSD and provides RAM  CPU  Battery and file system information    https   github com oshi oshi

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You can get some limited memory information from the Runtime class  It really isn t exactly what you are looking for  but I thought I would provide it for the sake of completeness  Here is a small example  Edit  You can also get disk usage information from the java io File class  The disk space usage stuff requires Java 1 6 or higher   public class Main     public static void main String   args           Total number of processors or cores available to the JVM        System out println  Available processors  cores                Runtime getRuntime   availableProcessors             Total amount of free memory available to the JVM        System out println  Free memory  bytes                Runtime getRuntime   freeMemory             This will return Long MAX VALUE if there is no preset limit        long maxMemory   Runtime getRuntime   maxMemory           Maximum amount of memory the JVM will attempt to use        System out println  Maximum memory  bytes                 maxMemory    Long MAX VALUE    no limit    maxMemory            Total memory currently available to the JVM        System out println  Total memory available to JVM  bytes                Runtime getRuntime   totalMemory             Get a list of all filesystem roots on this system        File   roots   File listRoots            For each filesystem root  print some info        for  File root   roots          System out println  File system root      root getAbsolutePath           System out println  Total space  bytes       root getTotalSpace           System out println  Free space  bytes       root getFreeSpace           System out println  Usable space  bytes       root getUsableSpace

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Hey you can do this with java com integration   By accessing WMI features you can get all the information

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Have a look at the APIs available in the java lang management package  For example     OperatingSystemMXBean getSystemLoadAverage   ThreadMXBean getCurrentThreadCpuTime   ThreadMXBean getCurrentThreadUserTime     There are loads of other useful things in there as well

[java] Get OS-level system information

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