diff --git a/cpp/src/db/db_impl.cpp b/cpp/src/db/db_impl.cpp
index b5c85b1c20..7f7e19a748 100644
--- a/cpp/src/db/db_impl.cpp
+++ b/cpp/src/db/db_impl.cpp
@@ -1,4 +1,5 @@
 #include <assert.h>
+#include <chrono>
 #include "db_impl.h"
 
 namespace vecengine {
@@ -9,8 +10,10 @@ DBImpl::DBImpl(const Options& options_, const std::string& name_)
       _options(options_),
       _bg_work_finish_signal(_mutex),
       _bg_compaction_scheduled(false),
+      _shutting_down(false),
       _pMeta(new DBMetaImpl(*(_options.pMetaOptions))),
       _pMemMgr(new MemManager(_pMeta)) {
+    start_timer_task(Options.memory_sync_interval);
 }
 
 Status DBImpl::add_group(const GroupOptions& options_,
@@ -39,7 +42,27 @@ Status DBImpl::get_group_files(const std::string& group_id_,
 
 Status DBImpl::add_vectors(const std::string& group_id_,
         size_t n, const float* vectors, IDNumbers& vector_ids_) {
-    return _pMemMgr->add_vectors(group_id_, n, vectors, vector_ids_);
+    Status status = _pMemMgr->add_vectors(group_id_, n, vectors, vector_ids_);
+    if (!status.ok()) {
+        return status;
+    }
+}
+
+void DBImpl::start_timer_task(int interval_) {
+    std::thread bg_task(&DBImpl::background_timer_task, this, interval_);
+    bg_task.detach();
+}
+
+void DBImpl::background_timer_task(int interval_) {
+    Status status;
+    while (true) {
+        if (!_bg_error.ok()) break;
+        if (_shutting_down.load(std::memory_order_acquire)) break;
+
+        std::this_thread::sleep_for(std::chrono::seconds(interval_));
+
+        try_schedule_compaction();
+    }
 }
 
 void DBImpl::try_schedule_compaction() {
@@ -61,14 +84,21 @@ void DBImpl::background_call() {
     if (!_bg_error.ok()) return;
 
     background_compaction();
+
+    _bg_compaction_scheduled = false;
+    _bg_work_finish_signal.notify_all();
 }
 
 void DBImpl::background_compaction() {
-
+    _pMemMgr->serialize();
 }
 
-void DBImpl::compact_memory() {
-
+DBImpl::~DBImpl() {
+    std::lock_guard<std::mutex> _mutex;
+    _shutting_down.store(true, std::memory_order_release);
+    while (_bg_compaction_scheduled) {
+        _bg_work_finish_signal.wait();
+    }
 }
 
 /*
diff --git a/cpp/src/db/db_impl.h b/cpp/src/db/db_impl.h
index 03fc3d3c0b..70ab2c5a2e 100644
--- a/cpp/src/db/db_impl.h
+++ b/cpp/src/db/db_impl.h
@@ -49,6 +49,7 @@ private:
     std::condition_variable _bg_work_finish_signal;
     bool _bg_compaction_scheduled;
     Status _bg_error;
+    std::atomic<bool> _shutting_down;
 
     std::shared_ptr<Meta> _pMeta;
     std::shared_ptr<MemManager> _pMemMgr;
diff --git a/cpp/src/db/memvectors.cpp b/cpp/src/db/memvectors.cpp
index f546fcf02b..f76589a628 100644
--- a/cpp/src/db/memvectors.cpp
+++ b/cpp/src/db/memvectors.cpp
@@ -52,7 +52,7 @@ MemVectors::~MemVectors() {
  * MemManager
  */
 
-MemVectors* MemManager::get_mem_by_group(const std::string& group_id_) {
+VectorsPtr MemManager::get_mem_by_group(const std::string& group_id_) {
     auto memIt = _memMap.find(group_id_);
     if memIt != _memMap.end() {
         return &(memIt->second);
@@ -63,15 +63,16 @@ MemVectors* MemManager::get_mem_by_group(const std::string& group_id_) {
     if (!status.ok()) {
         return nullptr;
     }
-    _memMap[group_id] = MemVectors(group_info.dimension, group_info.next_file_location);
-    return &(_memMap[group_id]);
+    _memMap[group_id] = std::shared_ptr<MemVectors>(new MemVectors(group_info.dimension,
+                group_info.next_file_location));
+    return _memMap[group_id];
 }
 
 Status MemManager::add_vectors(const std::string& group_id_,
         size_t n_,
         const float* vectors_,
         IDNumbers& vector_ids_) {
-    // PXU TODO
+    std::lock_guard<std::mutex> lock(_mutex);
     return add_vectors_no_lock(group_id_, n_, vectors_, vector_ids_);
 }
 
@@ -86,5 +87,35 @@ Status MemManager::add_vectors_no_lock(const std::string& group_id_,
     return mem->add(n, vectors, vector_ids_);
 }
 
+Status MemManager::mark_memory_as_immutable() {
+    std::lock_guard<std::mutex> lock(_mutex);
+    for (auto& kv: _memMap) {
+        _immMems.push_back(kv.second);
+    }
+    _memMap.clear();
+}
+
+/* bool MemManager::need_serialize(double interval) { */
+/*     if (_immMems.size() > 0) { */
+/*         return false; */
+/*     } */
+
+/*     auto diff = std::difftime(std::time(nullptr), _last_compact_time); */
+/*     if (diff >= interval) { */
+/*         return true; */
+/*     } */
+
+/*     return false; */
+/* } */
+
+Status MemManager::serialize() {
+    mark_memory_as_immutable();
+    for (auto& mem : _immMems) {
+        mem->serialize()
+    }
+    _immMems.clear();
+    /* _last_compact_time = std::time(nullptr); */
+}
+
 
 } // namespace vecengine
diff --git a/cpp/src/db/memvectors.h b/cpp/src/db/memvectors.h
index a6741971a1..aff162a15e 100644
--- a/cpp/src/db/memvectors.h
+++ b/cpp/src/db/memvectors.h
@@ -3,6 +3,7 @@
 
 #include <map>
 #include <string>
+#include <ctime>
 #include "id_generators.h"
 #include "status.h"
 
@@ -42,20 +43,28 @@ class Meta;
 
 class MemManager {
 public:
-    MemManager(const std::shared_ptr<Meta>& meta_) : _pMeta(meta_) {}
+    typedef std::shared_ptr<MemVectors> VectorsPtr;
+    MemManager(const std::shared_ptr<Meta>& meta_)
+        : _pMeta(meta_), _last_compact_time(std::time(nullptr)) {}
 
-    MemVectors* get_mem_by_group(const std::string& group_id_);
+    VectorsPtr get_mem_by_group(const std::string& group_id_);
 
     Status add_vectors(const std::string& group_id_,
             size_t n_, const float* vectors_, IDNumbers& vector_ids_);
 
+    Status serialize();
+
 private:
     Status add_vectors_no_lock(const std::string& group_id_,
             size_t n_, const float* vectors_, IDNumbers& vector_ids_);
 
-    typedef std::map<std::string, MemVectors> MemMap;
+    typedef std::map<std::string, VectorsPtr> MemMap;
+    typedef std::vector<VectorsPtr> ImmMemPool;
     MemMap _memMap;
+    ImmMemPool _immMems;
     std::shared_ptr<Meta> _pMeta;
+    std::time_t _last_compact_time;
+    std::mutex _mutex;
 }; // MemManager