boost priority of shutdown thread

router/java/src/net/i2p/router/Router.java

@@ -766,6 +766,9 @@ public class Router implements RouterClock.ClockShiftListener {
      *  NOT to be called by others, use shutdown().
      */
     public void shutdown2(int exitCode) {
+        // help us shut down esp. after OOM
+        int priority = (exitCode == EXIT_OOM) ? Thread.MAX_PRIORITY - 1 : Thread.NORM_PRIORITY + 2;
+        Thread.currentThread().setPriority(priority);
         _shutdownInProgress = true;
         _log.log(Log.CRIT, "Starting final shutdown(" + exitCode + ')');
         // So we can get all the way to the end

router/java/src/net/i2p/router/tasks/OOMListener.java

@@ -18,6 +18,8 @@ public class OOMListener implements I2PThread.OOMEventListener {
     }
 
     public void outOfMemory(OutOfMemoryError oom) { 
+        // boost priority to help us shut down
+        Thread.currentThread().setPriority(Thread.MAX_PRIORITY - 1);
         Router.clearCaches();
         Log log = _context.logManager().getLog(Router.class);
         log.log(Log.CRIT, "Thread ran out of memory, shutting down I2P", oom);