From 8da46a9d21dd154cf4509b74fae39fa7c51d478c Mon Sep 17 00:00:00 2001
From: Kevin <nekevss@gmail.com>
Date: Fri, 2 Dec 2022 16:28:54 +0000
Subject: [PATCH] Fix to weak_trace for `boa_tester` (#2470)

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This Pull Request fixes the current issue with the `boa_gc` when running `boa_tester` in parallel on Ubuntu. It looks like since we are running the `gc` in parallel something may not being cleaned up correctly that creates a reference cycle. The below changes should account for that.

It changes the following:

- Updates `weak_trace` to account for `Gc` reference cycles.
---
 boa_gc/src/internals/gc_box.rs | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/boa_gc/src/internals/gc_box.rs b/boa_gc/src/internals/gc_box.rs
index 9c5ac998d9..8ce48182ec 100644
--- a/boa_gc/src/internals/gc_box.rs
+++ b/boa_gc/src/internals/gc_box.rs
@@ -157,13 +157,16 @@ impl<T: Trace + ?Sized> GcBox<T> {
         }
     }
 
-    /// Trace inner data
+    /// Trace inner data and search for ephemerons to add to the ephemeron queue.
     #[inline]
     pub(crate) fn weak_trace_inner(&self) {
-        // SAFETY: if a `GcBox` has `weak_trace_inner` called, then the inner.
-        // value must have been deemed as reachable.
-        unsafe {
-            self.value.weak_trace();
+        if !self.header.is_marked() && !self.header.is_ephemeron() {
+            self.header.mark();
+            // SAFETY: if a `GcBox` has `weak_trace_inner` called, then the inner.
+            // value must have been deemed as reachable.
+            unsafe {
+                self.value.weak_trace();
+            }
         }
     }