diff --git a/src/replica/replica_stub.cpp b/src/replica/replica_stub.cpp
index 25fbdf4d16..5601b29145 100644
--- a/src/replica/replica_stub.cpp
+++ b/src/replica/replica_stub.cpp
@@ -202,6 +202,7 @@ replica_stub::replica_stub(replica_state_subscriber subscriber /*= nullptr*/,
     : serverlet("replica_stub"),
       _last_prevent_gc_replica_count(0),
       _real_log_shared_gc_flush_replicas_limit(0),
+      _mock_flush_replicas_for_test(0),
       _deny_client(false),
       _verbose_client_log(false),
       _verbose_commit_log(false),
@@ -1912,7 +1913,7 @@ void replica_stub::flush_replicas_for_slog_gc(const replica_gc_map &rs,
     _last_prevent_gc_replica_count = prevent_gc_replicas.size();
 
     std::ostringstream oss;
-    uint32_t i = 0;
+    size_t i = 0;
     for (const auto &pid : prevent_gc_replicas) {
         if (i != 0) {
             oss << ", ";
@@ -1921,20 +1922,32 @@ void replica_stub::flush_replicas_for_slog_gc(const replica_gc_map &rs,
         ++i;
     }
     LOG_INFO("gc_shared: trigger emergency checkpoints to flush replicas for gc shared logs: "
-             "log_shared_gc_flush_replicas_limit = {}, replicas({}) = {}",
+             "log_shared_gc_flush_replicas_limit = {}/{}, replicas({}) = {}",
+             _real_log_shared_gc_flush_replicas_limit,
              FLAGS_log_shared_gc_flush_replicas_limit,
              prevent_gc_replicas.size(),
              oss.str());
 
     i = 0;
     for (const auto &pid : prevent_gc_replicas) {
-        auto r = rs.find(pid);
+        const auto &r = rs.find(pid);
         if (r == rs.end()) {
             continue;
         }
 
-        if (FLAGS_log_shared_gc_flush_replicas_limit == 0 ||
-            ++i > FLAGS_log_shared_gc_flush_replicas_limit) {
+        if (++i > _real_log_shared_gc_flush_replicas_limit) {
+            break;
+        }
+
+        bool mock_flush = false;
+        FAIL_POINT_INJECT_NOT_RETURN_F(
+            "mock_flush_replicas_for_slog_gc", [&mock_flush, this, i](dsn::string_view str) {
+                CHECK(buf2bool(str, mock_flush),
+                      "invalid mock_flush_replicas_for_slog_gc toggle, should be true or false: {}",
+                      str);
+                _mock_flush_replicas_for_test = i;
+            });
+        if (dsn_unlikely(mock_flush)) {
             continue;
         }
 
diff --git a/src/replica/replica_stub.h b/src/replica/replica_stub.h
index bcb84571b6..be7e50084c 100644
--- a/src/replica/replica_stub.h
+++ b/src/replica/replica_stub.h
@@ -436,6 +436,7 @@ class replica_stub : public serverlet<replica_stub>, public ref_counter
     FRIEND_TEST(open_replica_test, open_replica_add_decree_and_ballot_check);
     FRIEND_TEST(replica_error_test, test_auto_trash_of_corruption);
     FRIEND_TEST(replica_test, test_clear_on_failure);
+    FRIEND_TEST(GcSlogFlushFeplicasTest, FlushReplicas);
 
     typedef std::unordered_map<gpid, ::dsn::task_ptr> opening_replicas;
     typedef std::unordered_map<gpid, std::tuple<task_ptr, replica_ptr, app_info, replica_info>>
@@ -450,6 +451,7 @@ class replica_stub : public serverlet<replica_stub>, public ref_counter
     closed_replicas _closed_replicas;
     size_t _last_prevent_gc_replica_count;
     size_t _real_log_shared_gc_flush_replicas_limit;
+    size_t _mock_flush_replicas_for_test;
 
     mutation_log_ptr _log;
     ::dsn::rpc_address _primary_address;
diff --git a/src/replica/test/mutation_log_test.cpp b/src/replica/test/mutation_log_test.cpp
index 16388e1bef..5b96d033f9 100644
--- a/src/replica/test/mutation_log_test.cpp
+++ b/src/replica/test/mutation_log_test.cpp
@@ -26,6 +26,7 @@
 
 #include "replica/mutation_log.h"
 
+// IWYU pragma: no_include <ext/alloc_traits.h>
 // IWYU pragma: no_include <gtest/gtest-message.h>
 // IWYU pragma: no_include <gtest/gtest-test-part.h>
 #include <gtest/gtest.h>
@@ -47,6 +48,7 @@
 #include "utils/binary_writer.h"
 #include "utils/blob.h"
 #include "utils/defer.h"
+#include "utils/fail_point.h"
 #include "utils/filesystem.h"
 #include "utils/fmt_logging.h"
 #include "utils/ports.h"
@@ -718,5 +720,42 @@ TEST_F(mutation_log_test, gc_slog)
     }
 }
 
+using gc_slog_flush_replicas_case = std::tuple<std::set<gpid>, uint64_t, size_t>;
+
+class GcSlogFlushFeplicasTest : public testing::TestWithParam<gc_slog_flush_replicas_case>
+{
+};
+
+TEST_P(GcSlogFlushFeplicasTest, FlushReplicas)
+{
+    std::set<gpid> prevent_gc_replicas;
+    uint64_t limit;
+    size_t expected_flush_replicas;
+    std::tie(prevent_gc_replicas, limit, expected_flush_replicas) = GetParam();
+
+    replica_stub::replica_gc_map rs;
+    for (const auto &r : prevent_gc_replicas) {
+        rs.emplace(r, replica_stub::gc_info());
+    }
+
+    dsn::fail::setup();
+    dsn::fail::cfg("mock_flush_replicas_for_slog_gc", "void(true)");
+
+    replica_stub stub;
+    stub.flush_replicas_for_slog_gc(rs, prevent_gc_replicas);
+    EXPECT_EQ(expected_flush_replicas, stub._mock_flush_replicas_for_test);
+
+    dsn::fail::teardown();
+}
+
+const std::vector<gc_slog_flush_replicas_case> gc_slog_flush_replicas_tests = {
+    {{{1, 1}, {1, 2}}, 0, 2},
+    // {{}, },
+};
+
+INSTANTIATE_TEST_CASE_P(MutationLogTest,
+                        GcSlogFlushFeplicasTest,
+                        testing::ValuesIn(gc_slog_flush_replicas_tests));
+
 } // namespace replication
 } // namespace dsn