diff --git a/homework/scripts/grade-utils.sh b/homework/scripts/grade-utils.sh
index aa1fa6ecd58..9823e9edeea 100755
--- a/homework/scripts/grade-utils.sh
+++ b/homework/scripts/grade-utils.sh
@@ -93,7 +93,7 @@ _run_tests_with() {
     local FAILED=0
     for TEST in "${TESTS[@]}"; do
         local TEST_CMD="$CARGO test $* $TEST"
-        timeout ${TIMEOUT:-20s} bash -c "$TEST_CMD 2>/dev/null" 1>&2
+        timeout ${TIMEOUT:-20s} bash -c "$TEST_CMD" 1>&2
         case $? in
             0) ;;
             124) echo_err "Test timed out: $TEST_CMD"; FAILED=$((FAILED + 1));;
diff --git a/homework/tests/list_set/main.rs b/homework/tests/list_set/main.rs
index db72a84c744..bcd66be4754 100644
--- a/homework/tests/list_set/main.rs
+++ b/homework/tests/list_set/main.rs
@@ -1,2 +1,5 @@
+// optimistic_fine_grained on thread santizer has very unstable performance on gg.
+#![feature(cfg_sanitize)]
+
 mod fine_grained;
 mod optimistic_fine_grained;
diff --git a/homework/tests/list_set/optimistic_fine_grained.rs b/homework/tests/list_set/optimistic_fine_grained.rs
index 9b05e1a52a9..b87bbe79cb1 100644
--- a/homework/tests/list_set/optimistic_fine_grained.rs
+++ b/homework/tests/list_set/optimistic_fine_grained.rs
@@ -90,14 +90,14 @@ fn stress_sequential() {
 
 #[test]
 fn stress_concurrent() {
-    const THREADS: usize = 16;
+    const THREADS: usize = if cfg!(sanitize = "thread") { 4 } else { 16 };
     const STEPS: usize = 4096 * 16;
     set::stress_concurrent::<u8, OptimisticFineGrainedListSet<u8>>(THREADS, STEPS);
 }
 
 #[test]
 fn log_concurrent() {
-    const THREADS: usize = 16;
+    const THREADS: usize = if cfg!(sanitize = "thread") { 4 } else { 16 };
     const STEPS: usize = 4096 * 16;
     set::log_concurrent::<u8, OptimisticFineGrainedListSet<u8>>(THREADS, STEPS);
 }
@@ -105,7 +105,7 @@ fn log_concurrent() {
 /// Check the consistency of iterator while other operations are running concurrently.
 #[test]
 fn iter_consistent() {
-    const THREADS: usize = 15;
+    const THREADS: usize = if cfg!(sanitize = "thread") { 3 } else { 15 };
     const STEPS: usize = 4096 * 16;
 
     let set = OptimisticFineGrainedListSet::new();