From f1614ec772b6922b707258ba40dbdb240d8de864 Mon Sep 17 00:00:00 2001
From: Cody Henthorne <cody@signal.org>
Date: Fri, 7 Mar 2025 10:36:44 -0500
Subject: [PATCH] Fix bounded-io thread pool race condition preventing
 additional thread starts.

---
 .../signal/core/util/concurrent/SignalExecutors.java | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/core-util/src/main/java/org/signal/core/util/concurrent/SignalExecutors.java b/core-util/src/main/java/org/signal/core/util/concurrent/SignalExecutors.java
index f9d95c6952..38437a0f38 100644
--- a/core-util/src/main/java/org/signal/core/util/concurrent/SignalExecutors.java
+++ b/core-util/src/main/java/org/signal/core/util/concurrent/SignalExecutors.java
@@ -5,12 +5,12 @@ import android.os.Process;
 
 import androidx.annotation.NonNull;
 
-import org.signal.core.util.LinkedBlockingLifoQueue;
 import org.signal.core.util.ThreadUtil;
 
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.SynchronousQueue;
 import java.util.concurrent.ThreadFactory;
 import java.util.concurrent.ThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
@@ -52,7 +52,7 @@ public final class SignalExecutors {
                                                            maxThreads,
                                                            timeoutSeconds,
                                                            TimeUnit.SECONDS,
-                                                           new LinkedBlockingQueue<Runnable>() {
+                                                           new SynchronousQueue<>() {
                                                              @Override
                                                              public boolean offer(Runnable runnable) {
                                                                if (isEmpty()) {
@@ -74,14 +74,6 @@ public final class SignalExecutors {
     return threadPool;
   }
 
-  /**
-   * Returns an executor that prioritizes newer work. This is the opposite of a traditional executor,
-   * which processor work in FIFO order.
-   */
-  public static ExecutorService newFixedLifoThreadExecutor(String name, int minThreads, int maxThreads) {
-    return new ThreadPoolExecutor(minThreads, maxThreads, 0, TimeUnit.MILLISECONDS, new LinkedBlockingLifoQueue<>(), new NumberedThreadFactory(name, ThreadUtil.PRIORITY_BACKGROUND_THREAD));
-  }
-
   public static HandlerThread getAndStartHandlerThread(@NonNull String name, int priority) {
     HandlerThread handlerThread = new HandlerThread(name, priority);
     handlerThread.start();