Router: Ensure log gzipper finishes after shutdown signal

core/java/src/net/i2p/util/FileLogWriter.java

@@ -118,13 +118,17 @@ class FileLogWriter extends LogWriter {
             } catch (IOException ioe) {}
         }
         if (_manager.shouldGzip() && currentFile != null && currentFile.length() >= _manager.getMinGzipSize()) {
+            // we always start a non-daemon thread for this,
+            // because the thread we are in now is a daemon thread.
             Thread gzipper = new Gzipper(currentFile);
             if (threadGzipper) {
+                // rotate
                 gzipper.setPriority(Thread.MIN_PRIORITY);
-                gzipper.start();  // rotate
             } else {
-                gzipper.run();  // shutdown
+                // shutdown
+                gzipper.setPriority(Thread.MAX_PRIORITY - 1);
             }
+            gzipper.start();
         }
     }
 

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

@@ -1713,7 +1713,12 @@ public class Router implements RouterClock.ClockShiftListener {
         changeState(State.FINAL_SHUTDOWN_3);
         clearCaches();
         _log.log(Log.CRIT, "Shutdown(" + exitCode + ") complete"  /* , new Exception("Shutdown") */ );
+        boolean waitForGzip = _context.logManager().shouldGzip();
         try { _context.logManager().shutdown(); } catch (Throwable t) { }
+        if (waitForGzip && !_killVMOnEnd) {
+            // ShutdownHook calls setKillVMOnEnd(false)
+            try { Thread.sleep(2000); } catch (InterruptedException ie) {}
+        }
         if (ALLOW_DYNAMIC_KEYS) {
             if (_context.getBooleanProperty(PROP_DYNAMIC_KEYS))
                 killKeys();