From 7092365546fe4d64b1a1f979d34298c9a4b802a5 Mon Sep 17 00:00:00 2001
From: Brent Shaffer <betterbrent@google.com>
Date: Wed, 2 Sep 2026 20:41:01 +0000
Subject: [PATCH] chore: fix gRPC fork deadlock in unit tests by enabling fork
 support

When the PHP gRPC extension is loaded, calling pcntl_fork() and exiting in the
child causes a futex deadlock in gRPC C-core due to unreleased locks / missing
background threads in the child process.

Enabling GRPC_ENABLE_FORK_SUPPORT=1 registers gRPC's pthread_atfork handlers,
allowing child processes to exit cleanly. Also adds a skip guard to
RaceConditionTest if gRPC is loaded without fork support enabled.
---
 .github/run-package-tests.sh           | 1 +
 .github/workflows/unit-tests.yaml      | 4 ++++
 Auth/phpunit.xml.dist                  | 3 +++
 Auth/tests/Cache/RaceConditionTest.php | 5 +++++
 phpunit.xml.dist                       | 1 +
 5 files changed, 14 insertions(+)

diff --git a/.github/run-package-tests.sh b/.github/run-package-tests.sh
index 489ce26317cd..e868e242d9ea 100644
--- a/.github/run-package-tests.sh
+++ b/.github/run-package-tests.sh
@@ -156,6 +156,7 @@ export -f run_package_test_parallel
 export STRICT
 export PREFER_LOWEST
 export FAILED_FILE
+export GRPC_ENABLE_FORK_SUPPORT=1
 
 # Determine optimal parallelism: default to the number of CPU cores on the host runner
 MAX_JOBS=${MAX_JOBS:-$(nproc 2>/dev/null || echo 8)}
diff --git a/.github/workflows/unit-tests.yaml b/.github/workflows/unit-tests.yaml
index fa11eefebc69..3fa419126f44 100644
--- a/.github/workflows/unit-tests.yaml
+++ b/.github/workflows/unit-tests.yaml
@@ -7,6 +7,10 @@ on:
 
 permissions:
   contents: read
+
+env:
+  GRPC_ENABLE_FORK_SUPPORT: 1
+
 jobs:
   test:
     strategy:
diff --git a/Auth/phpunit.xml.dist b/Auth/phpunit.xml.dist
index 2e2253269177..127b65307ed6 100644
--- a/Auth/phpunit.xml.dist
+++ b/Auth/phpunit.xml.dist
@@ -13,4 +13,7 @@
       <directory suffix="Test.php">tests</directory>
     </testsuite>
   </testsuites>
+  <php>
+    <env name="GRPC_ENABLE_FORK_SUPPORT" value="1"/>
+  </php>
 </phpunit>
diff --git a/Auth/tests/Cache/RaceConditionTest.php b/Auth/tests/Cache/RaceConditionTest.php
index 34d8b4249fea..63a7463c6ff7 100644
--- a/Auth/tests/Cache/RaceConditionTest.php
+++ b/Auth/tests/Cache/RaceConditionTest.php
@@ -45,6 +45,11 @@ public function testRaceCondition(string $cacheClass)
         if (!function_exists('pcntl_fork')) {
             $this->markTestSkipped('pcntl_fork is not available');
         }
+        if (extension_loaded('grpc') && !getenv('GRPC_ENABLE_FORK_SUPPORT')) {
+            $this->markTestSkipped(
+                'Cannot run fork test with grpc extension unless GRPC_ENABLE_FORK_SUPPORT=1 is set.'
+            );
+        }
         for ($i = 0; $i < 50; $i++) {
             // SysV Cache warmup to prevent segment creation race
             if ($cacheClass === SysVCacheItemPool::class) {
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index f94c12e3fbb3..486f85902371 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -30,6 +30,7 @@
   </testsuites>
   <php>
     <ini name="memory_limit" value="2048M"/>
+    <env name="GRPC_ENABLE_FORK_SUPPORT" value="1"/>
   </php>
 
 </phpunit>