From 3dcfdaf531f2ffbebf8c2a555c894212746be99c Mon Sep 17 00:00:00 2001
From: Kushal Pisavadia <kushal_p@apple.com>
Date: Thu, 23 Oct 2025 11:53:25 +0100
Subject: [PATCH 1/2] TaskQueueTest: Fix race condition in TaskSignalHandling
 test

Replace `sleep` with `condition_variable` synchronization to ensure the child
PID is captured before attempting to kill it. This eliminates timing
dependencies.
---
 unittests/Basic/TaskQueueTest.cpp | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/unittests/Basic/TaskQueueTest.cpp b/unittests/Basic/TaskQueueTest.cpp
index 460db418551a4..85085d3f496a7 100644
--- a/unittests/Basic/TaskQueueTest.cpp
+++ b/unittests/Basic/TaskQueueTest.cpp
@@ -18,6 +18,7 @@
 
 #include <algorithm>
 #include <chrono>
+#include <condition_variable>
 #include <mutex>
 #include <thread>
 
@@ -93,9 +94,15 @@ TEST(TaskQueueTest, TaskSignalHandling) {
   bool TaskSignalled = false;
   int ReceivedSignal = 0;
   ProcessId ChildPid = 0;
+  std::mutex PidMutex;
+  std::condition_variable PidCv;
 
   auto TaskBegan = [&](ProcessId Pid, void *Context) {
-    ChildPid = Pid;
+    {
+      std::lock_guard<std::mutex> lock(PidMutex);
+      ChildPid = Pid;
+    }
+    PidCv.notify_one();
   };
 
   auto TaskSignalledCallback = [&](ProcessId Pid, llvm::StringRef ErrorMsg,
@@ -117,7 +124,11 @@ TEST(TaskQueueTest, TaskSignalHandling) {
     TQ.execute(TaskBegan, nullptr, TaskSignalledCallback);
   });
 
-  std::this_thread::sleep_for(std::chrono::milliseconds(100));
+  // Wait for the task to actually start and get its PID
+  {
+    std::unique_lock<std::mutex> lock(PidMutex);
+    PidCv.wait_for(lock, std::chrono::seconds(5), [&] { return ChildPid > 0; });
+  }
 
   if (ChildPid > 0) {
     EXPECT_EQ(0, kill(ChildPid, SIGTERM)) << "Should kill the specific child process we spawned";

From 8f14263fd55b4da31d817e1cd24ddc1aa8008853 Mon Sep 17 00:00:00 2001
From: Kushal Pisavadia <kushal_p@apple.com>
Date: Thu, 23 Oct 2025 12:40:57 +0100
Subject: [PATCH 2/2] TaskQueue: Add destructor to close FDs, preventing
 resource leak

The `Task` class was missing a destructor to close pipe file descriptors when
destroyed. This caused file descriptor exhaustion after ~2,187 test runs,
making tests fail with POLLNVAL errors when the system ran out of resources.

This was found with:
```
./unittests/Basic/SwiftBasicTests --gtest_filter="TaskQueueTest.*" --gtest_repeat=1000
```
---
 lib/Basic/Unix/TaskQueue.inc | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/lib/Basic/Unix/TaskQueue.inc b/lib/Basic/Unix/TaskQueue.inc
index 3aaf9ffe93d29..bfd46a68797d6 100644
--- a/lib/Basic/Unix/TaskQueue.inc
+++ b/lib/Basic/Unix/TaskQueue.inc
@@ -114,6 +114,18 @@ public:
            "Env must either be empty or null-terminated!");
   }
 
+  ~Task() {
+    // Ensure pipes are closed when the task is destroyed
+    if (Pipe >= 0) {
+      close(Pipe);
+      Pipe = -1;
+    }
+    if (ErrorPipe >= 0) {
+      close(ErrorPipe);
+      ErrorPipe = -1;
+    }
+  }
+
   const char *getExecPath() const { return ExecPath; }
   ArrayRef<const char *> getArgs() const { return Args; }
   StringRef getOutput() const { return Output; }