Finding Number of Cores in Java

Question

How can I find the number of cores available to my application from within Java code

User · Answer

This works on Windows with Cygwin installed   System getenv  NUMBER OF PROCESSORS

User · Answer

This is an additional way to find out the number of CPU cores  and a lot of other information   but this code requires an additional dependence      Native Operating System and Hardware Information   https   github com oshi oshi   SystemInfo systemInfo   new SystemInfo    HardwareAbstractionLayer hardwareAbstractionLayer   systemInfo getHardware    CentralProcessor centralProcessor   hardwareAbstractionLayer getProcessor      Get the number of logical CPUs available for processing   centralProcessor getLogicalProcessorCount

User · Answer

int cores   Runtime getRuntime   availableProcessors      If cores is less than one  either your processor is about to die  or your JVM has a serious bug in it  or the universe is about to blow up

User · Answer

If you want to dubbel check the amount of cores you have on your machine to the number your java program is giving you  In Linux terminal  lscpu In Windows terminal  cmd   echo  NUMBER OF PROCESSORS  In Mac terminal  sysctl -n hw ncpu

User · Answer

If you want to get number of physical cores you can run cmd and terminal command and then to parse the output to get info you need Below is shown function that returns number of physical cores    private int getNumberOfCPUCores         OSValidator osValidator   new OSValidator        String command           if osValidator isMac             command    sysctl -n machdep cpu core count        else if osValidator isUnix             command    lscpu        else if osValidator isWindows             command    cmd  C WMIC CPU Get  Format List             Process process   null      int numberOfCores   0      int sockets   0      try           if osValidator isMac                 String   cmd       bin sh    -c   command               process   Runtime getRuntime   exec cmd            else              process   Runtime getRuntime   exec command                   catch  IOException e            e printStackTrace               BufferedReader reader   new BufferedReader              new InputStreamReader process getInputStream          String line       try           while   line   reader readLine       null                if osValidator isMac                     numberOfCores   line length    gt  0   Integer parseInt line    0               else if  osValidator isUnix                      if  line contains  Core s  per socket                           numberOfCores   Integer parseInt line split    s    line split    s    length - 1                                      if line contains  Socket s                           sockets   Integer parseInt line split    s    line split    s    length - 1                                    else if  osValidator isWindows                      if  line contains  NumberOfCores                          numberOfCores   Integer parseInt line split      1                                                    catch  IOException e            e printStackTrace              if osValidator isUnix             return numberOfCores   sockets            return numberOfCores      OSValidator class   public class OSValidator    private static String OS   System getProperty  os name   toLowerCase     public static void main String   args         System out println OS        if  isWindows              System out println  This is Windows          else if  isMac              System out println  This is Mac          else if  isUnix              System out println  This is Unix or Linux          else if  isSolaris              System out println  This is Solaris          else           System out println  Your OS is not support               public static boolean isWindows         return  OS indexOf  win    gt   0      public static boolean isMac         return  OS indexOf  mac    gt   0      public static boolean isUnix         return  OS indexOf  nix    gt   0    OS indexOf  nux    gt   0    OS indexOf  aix    gt  0       public static boolean isSolaris         return  OS indexOf  sunos    gt   0     public static String getOS        if  isWindows              return  win         else if  isMac              return  osx         else if  isUnix              return  uni         else if  isSolaris              return  sol         else           return  err

[java] Finding Number of Cores in Java

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