diff --git a/trunk/src/app/srs_app_server.cpp b/trunk/src/app/srs_app_server.cpp
index b21d2cd24..9950b4fc2 100644
--- a/trunk/src/app/srs_app_server.cpp
+++ b/trunk/src/app/srs_app_server.cpp
@@ -817,7 +817,7 @@ srs_error_t SrsServer::initialize_st()
     }
     
     // set current log id.
-    _srs_context->generate_id();
+    _srs_context->set_id(_srs_context->generate_id());
     
     // check asprocess.
     bool asprocess = _srs_config->get_asprocess();
diff --git a/trunk/src/app/srs_app_st.cpp b/trunk/src/app/srs_app_st.cpp
index 2df8ddbf8..5fc7fe528 100755
--- a/trunk/src/app/srs_app_st.cpp
+++ b/trunk/src/app/srs_app_st.cpp
@@ -197,11 +197,10 @@ SrsContextId SrsSTCoroutine::cid()
 srs_error_t SrsSTCoroutine::cycle()
 {
     if (_srs_context) {
-        if (!cid_.empty()) {
-            _srs_context->set_id(cid_);
-        } else {
+        if (cid_.empty()) {
             cid_ = _srs_context->generate_id();
         }
+        _srs_context->set_id(cid_);
     }
     
     srs_error_t err = handler->cycle();
diff --git a/trunk/src/kernel/srs_kernel_log.hpp b/trunk/src/kernel/srs_kernel_log.hpp
index ed7c6d75b..dbf149cf2 100644
--- a/trunk/src/kernel/srs_kernel_log.hpp
+++ b/trunk/src/kernel/srs_kernel_log.hpp
@@ -80,21 +80,22 @@ public:
 // The logic context, for example, a RTMP connection, or RTC Session, etc.
 // We can grep the context id to identify the logic unit, for debugging.
 // For example:
-//      _srs_context->generate_id(); // Generate a new context id.
-//      _srs_context->get_id(); // Get current context id.
-//      int old_id = _srs_context->set_id("1000"); // Change the context id.
+//      SrsContextId cid = _srs_context->get_id(); // Get current context id.
+//      SrsContextId new_cid = _srs_context->generate_id(); // Generate a new context id.
+//      SrsContextId old_cid = _srs_context->set_id(new_cid); // Change the context id.
 class ISrsContext
 {
 public:
     ISrsContext();
     virtual ~ISrsContext();
 public:
-    // Generate the id for current context.
+    // Generate a new context id.
+    // @remark We do not set to current thread, user should do this.
     virtual SrsContextId generate_id() = 0;
-    // Get the generated id of current context.
+    // Get the context id of current thread.
     virtual SrsContextId get_id() = 0;
-    // Set the id of current context.
-    // @return the previous id value; 0 if no context.
+    // Set the context id of current thread.
+    // @return the previous context id.
     virtual SrsContextId set_id(SrsContextId v) = 0;
 };
 
diff --git a/trunk/src/main/srs_main_server.cpp b/trunk/src/main/srs_main_server.cpp
index e9d6e51be..6ec4d01f7 100644
--- a/trunk/src/main/srs_main_server.cpp
+++ b/trunk/src/main/srs_main_server.cpp
@@ -213,7 +213,7 @@ srs_error_t do_main(int argc, char** argv)
 
 int main(int argc, char** argv) {
     // For background context id.
-    _srs_context->generate_id();
+    _srs_context->set_id(_srs_context->generate_id());
 
     srs_error_t err = do_main(argc, argv);
 
diff --git a/trunk/src/protocol/srs_service_log.cpp b/trunk/src/protocol/srs_service_log.cpp
index 437dc672b..3d711343b 100644
--- a/trunk/src/protocol/srs_service_log.cpp
+++ b/trunk/src/protocol/srs_service_log.cpp
@@ -46,7 +46,6 @@ SrsThreadContext::~SrsThreadContext()
 SrsContextId SrsThreadContext::generate_id()
 {
     SrsContextId cid = SrsContextId(srs_random_str(8));
-    cache[srs_thread_self()] = cid;
     return cid;
 }
 
diff --git a/trunk/src/protocol/srs_service_st.cpp b/trunk/src/protocol/srs_service_st.cpp
index f33167882..f2fbf20e5 100644
--- a/trunk/src/protocol/srs_service_st.cpp
+++ b/trunk/src/protocol/srs_service_st.cpp
@@ -70,7 +70,7 @@ srs_error_t srs_st_init()
         return srs_error_new(ERROR_ST_SET_EPOLL, "st enable st failed, current is %s", st_get_eventsys_name());
     }
 
-    // Before ST init, we might have already inited the background cid.
+    // Before ST init, we might have already initialized the background cid.
     SrsContextId cid = _srs_context->get_id();
     if (cid.empty()) {
         cid = _srs_context->generate_id();