From 85f39b4f1c59ddf7182ffa08b089dc8875e9ec6e Mon Sep 17 00:00:00 2001
From: Marvin Froeder <velo.br@gmail.com>
Date: Wed, 18 Mar 2026 06:59:39 -0300
Subject: [PATCH] Replace static ExecutorService singleton with per-instance
 executor to fix ClassLoader leak (#3178)

Signed-off-by: Marvin Froeder <velo.br@gmail.com>
---
 core/src/main/java/feign/AsyncFeign.java      | 19 ++++++++-----------
 .../java/feign/kotlin/CoroutineFeign.java     | 19 ++++++++-----------
 2 files changed, 16 insertions(+), 22 deletions(-)

diff --git a/core/src/main/java/feign/AsyncFeign.java b/core/src/main/java/feign/AsyncFeign.java
index 67948dd46..8f9c17f9b 100644
--- a/core/src/main/java/feign/AsyncFeign.java
+++ b/core/src/main/java/feign/AsyncFeign.java
@@ -55,23 +55,20 @@ public static <C> AsyncBuilder<C> asyncBuilder() {
     return builder();
   }
 
-  private static class LazyInitializedExecutorService {
-
-    private static final ExecutorService instance =
-        Executors.newCachedThreadPool(
-            r -> {
-              final Thread result = new Thread(r);
-              result.setDaemon(true);
-              return result;
-            });
+  private static ExecutorService newDefaultExecutorService() {
+    return Executors.newCachedThreadPool(
+        r -> {
+          final Thread result = new Thread(r);
+          result.setDaemon(true);
+          return result;
+        });
   }
 
   public static class AsyncBuilder<C> extends BaseBuilder<AsyncBuilder<C>, AsyncFeign<C>> {
 
     private AsyncContextSupplier<C> defaultContextSupplier = () -> null;
     private AsyncClient<C> client =
-        new DefaultAsyncClient<>(
-            new DefaultClient(null, null), LazyInitializedExecutorService.instance);
+        new DefaultAsyncClient<>(new DefaultClient(null, null), newDefaultExecutorService());
     private MethodInfoResolver methodInfoResolver = MethodInfo::new;
 
     @Deprecated
diff --git a/kotlin/src/main/java/feign/kotlin/CoroutineFeign.java b/kotlin/src/main/java/feign/kotlin/CoroutineFeign.java
index 4027e1d14..d974732f2 100644
--- a/kotlin/src/main/java/feign/kotlin/CoroutineFeign.java
+++ b/kotlin/src/main/java/feign/kotlin/CoroutineFeign.java
@@ -49,15 +49,13 @@ public static <C> CoroutineBuilder<C> coBuilder() {
     return builder();
   }
 
-  private static class LazyInitializedExecutorService {
-
-    private static final ExecutorService instance =
-        Executors.newCachedThreadPool(
-            r -> {
-              final Thread result = new Thread(r);
-              result.setDaemon(true);
-              return result;
-            });
+  private static ExecutorService newDefaultExecutorService() {
+    return Executors.newCachedThreadPool(
+        r -> {
+          final Thread result = new Thread(r);
+          result.setDaemon(true);
+          return result;
+        });
   }
 
   private static class CoroutineFeignInvocationHandler<T> implements InvocationHandler {
@@ -119,8 +117,7 @@ public static class CoroutineBuilder<C>
 
     private AsyncContextSupplier<C> defaultContextSupplier = () -> null;
     private AsyncClient<C> client =
-        new DefaultAsyncClient<>(
-            new DefaultClient(null, null), LazyInitializedExecutorService.instance);
+        new DefaultAsyncClient<>(new DefaultClient(null, null), newDefaultExecutorService());
     private MethodInfoResolver methodInfoResolver = KotlinMethodInfo::createInstance;
 
     @Deprecated