diff --git a/deps/oblib/src/lib/allocator/ob_slice_alloc.h b/deps/oblib/src/lib/allocator/ob_slice_alloc.h
index 613e88dafc..a8f1cf0b71 100644
--- a/deps/oblib/src/lib/allocator/ob_slice_alloc.h
+++ b/deps/oblib/src/lib/allocator/ob_slice_alloc.h
@@ -236,6 +236,12 @@ public:
     h ^= h >> 33;
     return h;
   }
+  static int32_t get_blk_size(int32_t slice_size, int32_t slice_cnt)
+  {
+    int32_t isize = (int32_t)lib::align_up2(sizeof(Item) + slice_size, 16);
+    int32_t blk_size = (isize + sizeof(void*)) * slice_cnt + sizeof(ObBlockSlicer);
+    return blk_size;
+  }
   Item* alloc_item() {
     Item* ret = NULL;
     ret = alloc_stock()? (Item*)flist_.pop(): NULL;
diff --git a/deps/oblib/src/lib/objectpool/ob_concurrency_objpool.h b/deps/oblib/src/lib/objectpool/ob_concurrency_objpool.h
index b13ad36131..65227255d1 100644
--- a/deps/oblib/src/lib/objectpool/ob_concurrency_objpool.h
+++ b/deps/oblib/src/lib/objectpool/ob_concurrency_objpool.h
@@ -45,9 +45,10 @@ class ObFixedClassAllocator
 public:
   using object_type = T;
 public:
-  ObFixedClassAllocator(const ObMemAttr &attr, int64_t nway)
+  ObFixedClassAllocator(const ObMemAttr &attr, int64_t nway, int32_t slice_cnt = 0)
     : allocator_(sizeof(T) + sizeof(ObClassMeta), attr,
-                 choose_blk_size(sizeof(T) + sizeof(ObClassMeta)))
+                 0 == slice_cnt ? choose_blk_size(sizeof(T) + sizeof(ObClassMeta)) :
+                                  ObBlockSlicer::get_blk_size(sizeof(T) + sizeof(ObClassMeta), slice_cnt))
   {
     allocator_.set_nway(static_cast<int32_t>(nway));
   }
diff --git a/src/sql/session/ob_sql_session_mgr.cpp b/src/sql/session/ob_sql_session_mgr.cpp
index 1d3d0ec380..6e2c614caa 100644
--- a/src/sql/session/ob_sql_session_mgr.cpp
+++ b/src/sql/session/ob_sql_session_mgr.cpp
@@ -97,7 +97,7 @@ int64_t ObTenantSQLSessionMgr::SessionPool::count() const
 
 ObTenantSQLSessionMgr::ObTenantSQLSessionMgr(const int64_t tenant_id)
   : tenant_id_(tenant_id),
-    session_allocator_(lib::ObMemAttr(tenant_id, "SQLSessionInfo"), MTL_CPU_COUNT())
+    session_allocator_(lib::ObMemAttr(tenant_id, "SQLSessionInfo"), MTL_CPU_COUNT(), 4)
 {}
 
 ObTenantSQLSessionMgr::~ObTenantSQLSessionMgr()
@@ -106,7 +106,7 @@ ObTenantSQLSessionMgr::~ObTenantSQLSessionMgr()
 int ObTenantSQLSessionMgr::init()
 {
   int ret = OB_SUCCESS;
-  if (OB_FAIL(session_pool_.init(MTL_IS_MINI_MODE() ? 32 : SessionPool::POOL_CAPACIPY))) {
+  if (OB_FAIL(session_pool_.init(SessionPool::POOL_CAPACIPY))) {
     LOG_WARN("fail to init session pool", K(tenant_id_), K(ret));
   }
   return ret;
diff --git a/src/sql/session/ob_sql_session_mgr.h b/src/sql/session/ob_sql_session_mgr.h
index fee5c47ea3..dc91ff406c 100644
--- a/src/sql/session/ob_sql_session_mgr.h
+++ b/src/sql/session/ob_sql_session_mgr.h
@@ -308,7 +308,7 @@ private:
   class SessionPool
   {
   public:
-    static const int64_t POOL_CAPACIPY = 512;
+    static const int64_t POOL_CAPACIPY = 32;
   public:
     SessionPool();
     int init(const int64_t capacity);