Add more debugging/error messages when mlockall fails

src/main/java/org/elasticsearch/bootstrap/JNACLibrary.java

@@ -20,27 +20,32 @@
 package org.elasticsearch.bootstrap;
 
 import com.sun.jna.Native;
+import com.sun.jna.Structure;
+
+import org.apache.lucene.util.Constants;
 import org.elasticsearch.common.logging.ESLogger;
 import org.elasticsearch.common.logging.Loggers;
 
+import java.util.Arrays;
+import java.util.List;
+
 
 /**
  *
  */
-class JNACLibrary {
+final class JNACLibrary {
 
     private static final ESLogger logger = Loggers.getLogger(JNACLibrary.class);
 
     public static final int MCL_CURRENT = 1;
-    public static final int MCL_FUTURE = 2;
-
     public static final int ENOMEM = 12;
+    public static final int RLIMIT_MEMLOCK = Constants.MAC_OS_X ? 6 : 8;
 
     static {
         try {
             Native.register("c");
         } catch (UnsatisfiedLinkError e) {
-            logger.warn("unable to link C library. native methods (mlockall) will be disabled.");
+            logger.warn("unable to link C library. native methods (mlockall) will be disabled.", e);
         }
     }
 
@@ -48,6 +53,25 @@ class JNACLibrary {
 
     static native int geteuid();
     
+    /** corresponds to struct rlimit */
+    public static final class Rlimit extends Structure implements Structure.ByReference {
+        public long rlim_cur = 0;
+        public long rlim_max = 0;
+        
+        @Override
+        protected List getFieldOrder() {
+            return Arrays.asList(new String[] { "rlim_cur", "rlim_max" });
+        }
+    }
+    
+    static native int getrlimit(int resource, Rlimit rlimit);
+    
+    static native String strerror(int errno);
+
     private JNACLibrary() {
     }
+    
+    public static void main(String args[]) throws Exception {
+        JNANatives.tryMlockall();
+    }
 }

src/main/java/org/elasticsearch/bootstrap/JNANatives.java

@@ -43,26 +43,40 @@ class JNANatives {
 
     static void tryMlockall() {
         int errno = Integer.MIN_VALUE;
+        String errMsg = null;
+        boolean rlimitSuccess = false;
+        long softLimit = 0;
+        long hardLimit = 0;
+        
         try {
             int result = JNACLibrary.mlockall(JNACLibrary.MCL_CURRENT);
-            if (result != 0) {
+            if (result == 0) {
-                errno = Native.getLastError();
-            } else {
                 LOCAL_MLOCKALL = true;
+                return;
+            }
+            
+            errno = Native.getLastError();
+            errMsg = JNACLibrary.strerror(errno);
+            JNACLibrary.Rlimit rlimit = new JNACLibrary.Rlimit();
+            if (JNACLibrary.getrlimit(JNACLibrary.RLIMIT_MEMLOCK, rlimit) == 0) {
+              rlimitSuccess = true;
+              softLimit = rlimit.rlim_cur;
+              hardLimit = rlimit.rlim_max;
+            } else {
+              logger.warn("Unable to retrieve resource limits: " + JNACLibrary.strerror(Native.getLastError()));
             }
         } catch (UnsatisfiedLinkError e) {
             // this will have already been logged by CLibrary, no need to repeat it
             return;
         }
 
-        if (errno != Integer.MIN_VALUE) {
+        // mlockall failed for some reason
-            if (errno == JNACLibrary.ENOMEM && System.getProperty("os.name").toLowerCase(Locale.ROOT).contains("linux")) {
+        logger.warn("Unable to lock JVM Memory: error=" + errno + ",reason=" + errMsg + ". This can result in part of the JVM being swapped out");
-                logger.warn("Unable to lock JVM memory (ENOMEM)."
+        if (errno == JNACLibrary.ENOMEM) {
-                        + " This can result in part of the JVM being swapped out."
+            if (rlimitSuccess) {
-                        + " Increase RLIMIT_MEMLOCK (ulimit).");
+                logger.warn("Increase RLIMIT_MEMLOCK (ulimit). soft limit:" + softLimit + ", hard limit:" + hardLimit);
-            } else if (!System.getProperty("os.name").toLowerCase(Locale.ROOT).contains("mac")) {
+            } else {
-                // OS X allows mlockall to be called, but always returns an error
+                logger.warn("Increase RLIMIT_MEMLOCK (ulimit).");
-                logger.warn("Unknown mlockall error " + errno);
             }
         }
     }