From 40ad52987f9715ae38cd7b9db20e73d6dd2beba0 Mon Sep 17 00:00:00 2001
From: zzz <zzz@i2pmail.org>
Date: Sat, 29 Aug 2026 12:17:50 -0400
Subject: [PATCH] Router: Ensure log gzipper finishes after shutdown signal

---
 core/java/src/net/i2p/util/FileLogWriter.java | 8 ++++++--
 router/java/src/net/i2p/router/Router.java    | 5 +++++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/core/java/src/net/i2p/util/FileLogWriter.java b/core/java/src/net/i2p/util/FileLogWriter.java
index c9b0d7021..d8729f93d 100644
--- a/core/java/src/net/i2p/util/FileLogWriter.java
+++ b/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();
         }
     }
 
diff --git a/router/java/src/net/i2p/router/Router.java b/router/java/src/net/i2p/router/Router.java
index c06ce38af..4b8a65a77 100644
--- a/router/java/src/net/i2p/router/Router.java
+++ b/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();