Use core affinity on windows to improve performance

src/com/sheepit/client/Job.java

@@ -221,6 +221,7 @@ public class Job {
 		Map<String, String> new_env = new HashMap<String, String>();
 		
 		new_env.put("BLENDER_USER_CONFIG", config.workingDirectory.getAbsolutePath().replace("\\", "\\\\"));
+		new_env.put("CORES", Integer.toString(config.getNbCores()));
 		
 		for (String arg : command1) {
 			switch (arg) {

src/com/sheepit/client/os/Windows.java

@@ -133,6 +133,10 @@ public class Windows extends OS {
 		Process p = builder.start();
 		WinProcess wproc = new WinProcess(p);
 		wproc.setPriority(WinProcess.PRIORITY_BELOW_NORMAL);
+		if (env != null) {
+			String cores = env.get("CORES");
+			wproc.setAffinity(Integer.parseInt(cores));
+		}
 		return p;
 	}
 	

src/com/sheepit/client/os/windows/Kernel32Lib.java

@@ -21,6 +21,7 @@ import com.sun.jna.Library;
 import com.sun.jna.Pointer;
 import com.sun.jna.Structure;
 import com.sun.jna.platform.win32.BaseTSD;
+import com.sun.jna.platform.win32.BaseTSD.DWORD_PTR;
 import com.sun.jna.platform.win32.WinDef;
 import com.sun.jna.platform.win32.WinDef.DWORD;
 import com.sun.jna.platform.win32.WinNT;
@@ -211,4 +212,13 @@ public interface Kernel32Lib extends Library {
 	 */
 	public int SetErrorMode(DWORD uMode);
 	
+	/**
+	 * See : https://msdn.microsoft.com/en-us/library/windows/desktop/ms686247%28v=vs.85%29.aspx
+	 * 
+	 * @param hThread
+	 * @param dwThreadAffinityMask
+	 * @return If the function succeeds, the return value is the thread's previous affinity mask.
+	 */
+	public boolean SetProcessAffinityMask(HANDLE hProcess, DWORD_PTR dwProcessAffinityMask);
+
 }

src/com/sheepit/client/os/windows/WinProcess.java

@@ -26,6 +26,7 @@ import java.util.List;
 
 import com.sun.jna.Native;
 import com.sun.jna.Pointer;
+import com.sun.jna.platform.win32.BaseTSD.DWORD_PTR;
 import com.sun.jna.platform.win32.Kernel32;
 import com.sun.jna.platform.win32.Kernel32Util;
 import com.sun.jna.platform.win32.WinDef.DWORD;
@@ -121,6 +122,20 @@ public class WinProcess {
 		return this.kernel32lib.SetPriorityClass(this.handle, priority);
 	}
 	
+	public boolean setAffinity(int numberCores) {
+		// affects the process to a specific core/cpu, it will reduce the number of switch between core
+		// that way the machine will look "less busy" since default behavior for windows is to put 4 cores 
+		// at 25% instead of 1 core at 100% but from the user point of view, it introduce lag.
+		if (numberCores > 0) {
+			long coreAffinity = 0;
+			for (int i = 0; i < numberCores; i++) {
+				coreAffinity |= 1L << i;
+			}
+			return this.kernel32lib.SetProcessAffinityMask(this.handle, new DWORD_PTR(coreAffinity));
+		}
+		return false;
+	}
+	
 	private void terminate() {
 		Kernel32.INSTANCE.TerminateProcess(this.handle, 0);
 		Kernel32.INSTANCE.CloseHandle(this.handle); // we are sure that the parent Process object is dead