diff --git a/srtcore/api.cpp b/srtcore/api.cpp
index ca26600d1..665593c39 100644
--- a/srtcore/api.cpp
+++ b/srtcore/api.cpp
@@ -174,8 +174,7 @@ srt::CUDTUnited::CUDTUnited()
     , m_GlobControlLock()
     , m_IDLock()
     , m_mMultiplexer()
-    , m_MultiplexerLock()
-    , m_pCache(NULL)
+    , m_pCache(new CCache<CInfoBlock>)
     , m_bClosing(false)
     , m_GCStopCond()
     , m_InitLock()
@@ -195,8 +194,6 @@ srt::CUDTUnited::CUDTUnited()
     setupMutex(m_GlobControlLock, "GlobControl");
     setupMutex(m_IDLock, "ID");
     setupMutex(m_InitLock, "Init");
-
-    m_pCache = new CCache<CInfoBlock>;
 }
 
 srt::CUDTUnited::~CUDTUnited()
diff --git a/srtcore/api.h b/srtcore/api.h
index fddbfc294..6dbad6634 100644
--- a/srtcore/api.h
+++ b/srtcore/api.h
@@ -385,11 +385,13 @@ class CUDTUnited
 
 private:
     typedef std::map<SRTSOCKET, CUDTSocket*> sockets_t; // stores all the socket structures
-    sockets_t                                m_Sockets;
+    SRT_ATTR_GUARDED_BY(m_GlobControlLock)
+    sockets_t m_Sockets;
 
 #if ENABLE_BONDING
     typedef std::map<SRTSOCKET, CUDTGroup*> groups_t;
-    groups_t                                m_Groups;
+    SRT_ATTR_GUARDED_BY(m_GlobControlLock)
+    groups_t m_Groups;
 #endif
 
     sync::Mutex m_GlobControlLock; // used to synchronize UDT API
@@ -399,6 +401,7 @@ class CUDTUnited
     SRTSOCKET m_SocketIDGenerator;      // seed to generate a new unique socket ID
     SRTSOCKET m_SocketIDGenerator_init; // Keeps track of the very first one
 
+    SRT_ATTR_GUARDED_BY(m_GlobControlLock)
     std::map<int64_t, std::set<SRTSOCKET> >
         m_PeerRec; // record sockets from peers to avoid repeated connection request, int64_t = (socker_id << 30) + isn
 
@@ -460,11 +463,13 @@ class CUDTUnited
         const sockaddr_any& reqaddr, const CSrtMuxerConfig& cfgSocket);
 
 private:
+    SRT_ATTR_GUARDED_BY(m_GlobControlLock)
     std::map<int, CMultiplexer> m_mMultiplexer; // UDP multiplexer
-    sync::Mutex                 m_MultiplexerLock;
 
-private:
-    CCache<CInfoBlock>* m_pCache; // UDT network information cache
+    /// UDT network information cache.
+    /// Existence is guarded by m_GlobControlLock, but the cache itself is thread-safe.
+    SRT_ATTR_GUARDED_BY(m_GlobControlLock)
+    CCache<CInfoBlock>* const m_pCache;
 
 private:
     srt::sync::atomic<bool> m_bClosing;
@@ -472,14 +477,19 @@ class CUDTUnited
     sync::Condition         m_GCStopCond;
 
     sync::Mutex m_InitLock;
+    SRT_ATTR_GUARDED_BY(m_InitLock)
     int         m_iInstanceCount; // number of startup() called by application
+    SRT_ATTR_GUARDED_BY(m_InitLock)
     bool        m_bGCStatus;      // if the GC thread is working (true)
 
+    SRT_ATTR_GUARDED_BY(m_InitLock)
     sync::CThread m_GCThread;
     static void*  garbageCollect(void*);
 
+    SRT_ATTR_GUARDED_BY(m_GlobControlLock)
     sockets_t m_ClosedSockets; // temporarily store closed sockets
 #if ENABLE_BONDING
+    SRT_ATTR_GUARDED_BY(m_GlobControlLock)
     groups_t m_ClosedGroups;
 #endif
 
diff --git a/srtcore/cache.h b/srtcore/cache.h
index 47633706a..d5a037633 100644
--- a/srtcore/cache.h
+++ b/srtcore/cache.h
@@ -192,9 +192,11 @@ template<typename T> class CCache
       return 0;
    }
 
-      /// Specify the cache size (i.e., max number of items).
-      /// @param [in] size max cache size.
+private:
 
+   /// Specify the cache size (i.e., max number of items).
+   /// Private or else must be protected by a lock.
+   /// @param [in] size max cache size.
    void setSizeLimit(int size)
    {
       m_iMaxSize = size;
@@ -202,8 +204,8 @@ template<typename T> class CCache
       m_vHashPtr.resize(m_iHashSize);
    }
 
-      /// Clear all entries in the cache, restore to initialization state.
-
+   /// Clear all entries in the cache, restore to initialization state.
+   /// Private or else must be protected by a lock.
    void clear()
    {
       for (typename std::list<T*>::iterator i = m_StorageList.begin(); i != m_StorageList.end(); ++ i)
diff --git a/srtcore/core.cpp b/srtcore/core.cpp
index 83ff52f16..b802bdec9 100644
--- a/srtcore/core.cpp
+++ b/srtcore/core.cpp
@@ -11946,7 +11946,7 @@ void srt::CUDT::processKeepalive(const CPacket& ctrlpkt, const time_point& tsArr
     if (m_parent->m_GroupOf)
     {
         // Lock GlobControlLock in order to make sure that
-        // the state if the socket having the group and the
+        // the state of the socket having the group and the
         // existence of the group will not be changed during
         // the operation. The attempt of group deletion will
         // have to wait until this operation completes.
diff --git a/srtcore/group.cpp b/srtcore/group.cpp
index d2d275bf6..d4598d7c1 100644
--- a/srtcore/group.cpp
+++ b/srtcore/group.cpp
@@ -3199,7 +3199,7 @@ void CUDTGroup::send_CloseBrokenSockets(vector<SRTSOCKET>& w_wipeme)
         InvertedLock ug(m_GroupLock);
 
         // With unlocked GroupLock, we can now lock GlobControlLock.
-        // This is needed prevent any of them be deleted from the container
+        // This is needed to prevent any of them deleted from the container
         // at the same time.
         ScopedLock globlock(CUDT::uglobal().m_GlobControlLock);