From b404d4b1429f2fdb36b3d28f6f8852d726d037e3 Mon Sep 17 00:00:00 2001
From: Stuart Douglas <stuart.w.douglas@gmail.com>
Date: Mon, 2 Aug 2021 16:01:54 +1000
Subject: [PATCH] Revert "Optimise the strategy we use to reset the classloader
 in the Common ForkJoin ThreadPool"

This reverts commit ae9a6345c229356d1ea8b536bab4535ca8e8ead7.

Fixes #19136
---
 .../bootstrap/ForkJoinClassLoading.java       | 55 ++++++++-----------
 1 file changed, 22 insertions(+), 33 deletions(-)

diff --git a/core/deployment/src/main/java/io/quarkus/runner/bootstrap/ForkJoinClassLoading.java b/core/deployment/src/main/java/io/quarkus/runner/bootstrap/ForkJoinClassLoading.java
index f9fedc368ebcb..784242bcdd81a 100644
--- a/core/deployment/src/main/java/io/quarkus/runner/bootstrap/ForkJoinClassLoading.java
+++ b/core/deployment/src/main/java/io/quarkus/runner/bootstrap/ForkJoinClassLoading.java
@@ -20,42 +20,31 @@ public class ForkJoinClassLoading {
      * Really we should just not use the common pool at all.
      */
     public static void setForkJoinClassLoader(ClassLoader classLoader) {
-        final ForkJoinPool commonPool = ForkJoinPool.commonPool();
-
-        final int activeThreadCount = commonPool.getActiveThreadCount();
-
-        //The following approach is rather heavy, but there's good chances that there are actually no active threads,
-        //so skip it in this case.
-        //Additionally, if we can skip this this will prevent us from actually forcing to start all threads in the pool.
-        if (activeThreadCount > 0) {
-            //TODO we could theoretically improve this by using the system property java.util.concurrent.ForkJoinPool.common.threadFactory
-            //and force the common pool to register created threads so that we can reach and reset them.
-            CountDownLatch allDone = new CountDownLatch(ForkJoinPool.getCommonPoolParallelism());
-            CountDownLatch taskRelease = new CountDownLatch(1);
-            for (int i = 0; i < ForkJoinPool.getCommonPoolParallelism(); ++i) {
-                commonPool.execute(new Runnable() {
-                    @Override
-                    public void run() {
-                        Thread.currentThread().setContextClassLoader(classLoader);
-                        allDone.countDown();
-                        try {
-                            taskRelease.await();
-                        } catch (InterruptedException e) {
-                            log.error("Failed to set fork join ClassLoader", e);
-                        }
+        CountDownLatch allDone = new CountDownLatch(ForkJoinPool.getCommonPoolParallelism());
+        CountDownLatch taskRelease = new CountDownLatch(1);
+        for (int i = 0; i < ForkJoinPool.getCommonPoolParallelism(); ++i) {
+            ForkJoinPool.commonPool().execute(new Runnable() {
+                @Override
+                public void run() {
+                    Thread.currentThread().setContextClassLoader(classLoader);
+                    allDone.countDown();
+                    try {
+                        taskRelease.await();
+                    } catch (InterruptedException e) {
+                        log.error("Failed to set fork join ClassLoader", e);
                     }
-                });
-            }
-            try {
-                if (!allDone.await(1, TimeUnit.SECONDS)) {
-                    log.error(
-                            "Timed out trying to set fork join ClassLoader, this should never happen unless something has tied up a fork join thread before the app launched");
                 }
-            } catch (InterruptedException e) {
-                log.error("Failed to set fork join ClassLoader", e);
-            } finally {
-                taskRelease.countDown();
+            });
+        }
+        try {
+            if (!allDone.await(1, TimeUnit.SECONDS)) {
+                log.error(
+                        "Timed out trying to set fork join ClassLoader, this should never happen unless something has tied up a fork join thread before the app launched");
             }
+        } catch (InterruptedException e) {
+            log.error("Failed to set fork join ClassLoader", e);
+        } finally {
+            taskRelease.countDown();
         }
     }
 }