From 9476ff9a9a0826a93ae1b533054ff79a24bae915 Mon Sep 17 00:00:00 2001
From: Irfan Bunjaku <irfan.bunjaku@relational.ai>
Date: Tue, 3 Mar 2026 14:39:17 +0100
Subject: [PATCH 1/2] [RAI-47876] Hard-code semaphore name to avoid
 thread-unsafe getenv calls

---
 src/aotcompile.cpp | 38 +++++++++++++++++++-------------------
 1 file changed, 19 insertions(+), 19 deletions(-)

diff --git a/src/aotcompile.cpp b/src/aotcompile.cpp
index 51f9bcf5f8e5b..56faea2e16efa 100644
--- a/src/aotcompile.cpp
+++ b/src/aotcompile.cpp
@@ -1666,27 +1666,27 @@ void jl_dump_native_impl(void *native_code,
     };
 
     sem_t *par_precomp_sem = SEM_FAILED;
-    const char *sem_name = getenv("JL_AOT_PRECOMPILE_SEMAPHORE");
-    if (sem_name != NULL) {
-        // The count for the semaphore will be initialized by the parent process that spawns compilation sub-processes.
-        // This is to ensure that only already created semaphores are used and that we don't end up in a situation
-        // where every spawned compilation subprocess creates its own semaphore. Cleanup is handled by the parent process.
-        par_precomp_sem = sem_open(sem_name, 0);
+    // Hard-coded semaphore name to avoid thread-unsafe getenv() calls (RAI-47876)
+    const char *sem_name = "/jl_aot_par_precomp_semaphore";
+    // Try to open the semaphore without O_CREAT. If it doesn't exist, sem_open will fail
+    // and we'll skip semaphore-based coordination (normal path when not using compcache).
+    // The count for the semaphore will be initialized by the parent process that spawns compilation sub-processes.
+    // This is to ensure that only already created semaphores are used and that we don't end up in a situation
+    // where every spawned compilation subprocess creates its own semaphore. Cleanup is handled by the parent process.
+    par_precomp_sem = sem_open(sem_name, 0);
+    if (par_precomp_sem != SEM_FAILED) {
+        // Semaphore exists, use it for coordination
         std::unique_ptr<sem_t, decltype(cleanup)> sem_guard(par_precomp_sem, cleanup);
-        if (par_precomp_sem == SEM_FAILED) {
-            jl_errorf("Failed to open parallel precompilation semaphore '%s': %s", sem_name, strerror(errno));
+        // Wait for the semaphore, retrying if interrupted by a signal (EINTR).
+        int ret;
+        do {
+            ret = sem_wait(par_precomp_sem);
+        } while (ret == -1 && errno == EINTR);
+
+        if (ret == 0) {
+            lock_acquired = true;
         } else {
-            // Wait for the semaphore, retrying if interrupted by a signal (EINTR).
-            int ret;
-            do {
-                ret = sem_wait(par_precomp_sem);
-            } while (ret == -1 && errno == EINTR);
-
-            if (ret == 0) {
-                lock_acquired = true;
-            } else {
-                jl_errorf("Failed to wait on semaphore '%s': %s", sem_name, strerror(errno));
-            }
+            jl_errorf("Failed to wait on semaphore '%s': %s", sem_name, strerror(errno));
         }
     }
 #endif

From 3f7f25dbcd47316005f49bbc8b917b76fbf60181 Mon Sep 17 00:00:00 2001
From: Irfan Bunjaku <irfan.bunjaku@relational.ai>
Date: Wed, 4 Mar 2026 10:47:25 +0100
Subject: [PATCH 2/2] [RAI-47876] Warn on unexpected sem_open errors (not
 ENOENT)

---
 src/aotcompile.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/aotcompile.cpp b/src/aotcompile.cpp
index 56faea2e16efa..be73d88887ff6 100644
--- a/src/aotcompile.cpp
+++ b/src/aotcompile.cpp
@@ -1688,6 +1688,10 @@ void jl_dump_native_impl(void *native_code,
         } else {
             jl_errorf("Failed to wait on semaphore '%s': %s", sem_name, strerror(errno));
         }
+    } else if (errno != ENOENT) {
+        // ENOENT means the semaphore doesn't exist, which is the normal path when not using
+        // compcache. Any other error is unexpected and worth surfacing.
+        jl_safe_printf("WARNING: sem_open(\"%s\") failed: %s\n", sem_name, strerror(errno));
     }
 #endif