From f94be665f12d85304db056c6cb8934870de3e45a Mon Sep 17 00:00:00 2001
From: Matthias Sohn <matthias.sohn@sap.com>
Date: Fri, 8 Sep 2023 02:32:57 +0200
Subject: [PATCH] Unregister ShutdownHook when GC#PidLock is closed

Otherwise the JVM will accumulate the ShutdownHook objects of all GCs
run while the JVM is up.

Change-Id: Iadc723a939238a3a75b4ba47f898918eb4554ea3
---
 .../org/eclipse/jgit/internal/storage/file/GC.java  | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/GC.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/GC.java
index df18d059d..fd9e55052 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/GC.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/GC.java
@@ -1799,6 +1799,8 @@ private class PidLock implements AutoCloseable {
 
 		private FileChannel channel;
 
+		private Thread cleanupHook;
+
 		PidLock() {
 			pidFile = repo.getDirectory().toPath().resolve(GC_PID);
 		}
@@ -1827,9 +1829,9 @@ boolean lock() throws IOException {
 				}
 				channel.write(ByteBuffer
 						.wrap(getProcDesc().getBytes(StandardCharsets.UTF_8)));
-				Thread cleanupHook = new Thread(() -> close());
 				try {
-					Runtime.getRuntime().addShutdownHook(cleanupHook);
+					Runtime.getRuntime().addShutdownHook(
+							cleanupHook = new Thread(() -> close()));
 				} catch (IllegalStateException e) {
 					// ignore - the VM is already shutting down
 				}
@@ -1901,6 +1903,13 @@ private String getHostName() {
 		public void close() {
 			boolean wasLocked = false;
 			try {
+				if (cleanupHook != null) {
+					try {
+						Runtime.getRuntime().removeShutdownHook(cleanupHook);
+					} catch (IllegalStateException e) {
+						// ignore - the VM is already shutting down
+					}
+				}
 				if (lock != null && lock.isValid()) {
 					lock.release();
 					wasLocked = true;