diff --git a/trunk/src/app/srs_app_async_call.cpp b/trunk/src/app/srs_app_async_call.cpp
index e32b536ff..f7904a041 100644
--- a/trunk/src/app/srs_app_async_call.cpp
+++ b/trunk/src/app/srs_app_async_call.cpp
@@ -38,7 +38,7 @@ ISrsAsyncCallTask::~ISrsAsyncCallTask()
 
 SrsAsyncCallWorker::SrsAsyncCallWorker()
 {
-    trd = NULL;
+    trd = new SrsDummyCoroutine();
     wait = srs_cond_new();
 }
 
@@ -74,7 +74,7 @@ int SrsAsyncCallWorker::count()
 int SrsAsyncCallWorker::start()
 {
     srs_freep(trd);
-    trd = new SrsCoroutine("async", this, _srs_context->get_id());
+    trd = new SrsSTCoroutine("async", this, _srs_context->get_id());
     return trd->start();
 }
 
diff --git a/trunk/src/app/srs_app_conn.cpp b/trunk/src/app/srs_app_conn.cpp
index fb215454c..0dbb06d72 100644
--- a/trunk/src/app/srs_app_conn.cpp
+++ b/trunk/src/app/srs_app_conn.cpp
@@ -41,7 +41,7 @@ SrsConnection::SrsConnection(IConnectionManager* cm, srs_netfd_t c, string cip)
     kbps = new SrsKbps();
     kbps->set_io(skt, skt);
     
-    trd = new SrsCoroutine("conn", this);
+    trd = new SrsSTCoroutine("conn", this);
 }
 
 SrsConnection::~SrsConnection()
diff --git a/trunk/src/app/srs_app_edge.cpp b/trunk/src/app/srs_app_edge.cpp
index efe649ef9..2d6defb7a 100644
--- a/trunk/src/app/srs_app_edge.cpp
+++ b/trunk/src/app/srs_app_edge.cpp
@@ -166,7 +166,7 @@ SrsEdgeIngester::SrsEdgeIngester()
     
     upstream = new SrsEdgeRtmpUpstream(redirect);
     lb = new SrsLbRoundRobin();
-    trd = NULL;
+    trd = new SrsDummyCoroutine();
 }
 
 SrsEdgeIngester::~SrsEdgeIngester()
@@ -199,7 +199,7 @@ int SrsEdgeIngester::start()
     }
     
     srs_freep(trd);
-    trd = new SrsCoroutine("edge-igs", this);
+    trd = new SrsSTCoroutine("edge-igs", this);
     return trd->start();
 }
 
@@ -423,7 +423,7 @@ SrsEdgeForwarder::SrsEdgeForwarder()
     
     sdk = NULL;
     lb = new SrsLbRoundRobin();
-    trd = NULL;
+    trd = new SrsDummyCoroutine();
     queue = new SrsMessageQueue();
 }
 
@@ -493,7 +493,8 @@ int SrsEdgeForwarder::start()
         return ret;
     }
     
-    trd = new SrsCoroutine("edge-fwr", this);
+    srs_freep(trd);
+    trd = new SrsSTCoroutine("edge-fwr", this);
     return trd->start();
 }
 
diff --git a/trunk/src/app/srs_app_encoder.cpp b/trunk/src/app/srs_app_encoder.cpp
index 39ba45876..96da82bd7 100644
--- a/trunk/src/app/srs_app_encoder.cpp
+++ b/trunk/src/app/srs_app_encoder.cpp
@@ -41,7 +41,7 @@ static std::vector<std::string> _transcoded_url;
 
 SrsEncoder::SrsEncoder()
 {
-    trd = NULL;
+    trd = new SrsDummyCoroutine();
     pprint = SrsPithyPrint::create_encoder();
 }
 
@@ -74,7 +74,7 @@ int SrsEncoder::on_publish(SrsRequest* req)
     
     // start thread to run all encoding engines.
     srs_freep(trd);
-    trd = new SrsCoroutine("encoder", this, _srs_context->get_id());
+    trd = new SrsSTCoroutine("encoder", this, _srs_context->get_id());
     if ((ret = trd->start()) != ERROR_SUCCESS) {
         srs_error("st_thread_create failed. ret=%d", ret);
         return ret;
diff --git a/trunk/src/app/srs_app_forward.cpp b/trunk/src/app/srs_app_forward.cpp
index 165c5e36d..05636cea7 100755
--- a/trunk/src/app/srs_app_forward.cpp
+++ b/trunk/src/app/srs_app_forward.cpp
@@ -55,7 +55,7 @@ SrsForwarder::SrsForwarder(SrsOriginHub* h)
     sh_video = sh_audio = NULL;
     
     sdk = NULL;
-    trd = NULL;
+    trd = new SrsDummyCoroutine();
     queue = new SrsMessageQueue();
     jitter = new SrsRtmpJitter();
 }
@@ -136,7 +136,7 @@ int SrsForwarder::on_publish()
               req->stream.c_str());
     
     srs_freep(trd);
-    trd = new SrsCoroutine("forward", this);
+    trd = new SrsSTCoroutine("forward", this);
     if ((ret = trd->start()) != ERROR_SUCCESS) {
         srs_error("start srs thread failed. ret=%d", ret);
         return ret;
diff --git a/trunk/src/app/srs_app_http_stream.cpp b/trunk/src/app/srs_app_http_stream.cpp
index f85ea1e86..a948a9391 100755
--- a/trunk/src/app/srs_app_http_stream.cpp
+++ b/trunk/src/app/srs_app_http_stream.cpp
@@ -60,7 +60,7 @@ SrsBufferCache::SrsBufferCache(SrsSource* s, SrsRequest* r)
     req = r->copy();
     source = s;
     queue = new SrsMessageQueue(true);
-    trd = new SrsCoroutine("http-stream", this);
+    trd = new SrsSTCoroutine("http-stream", this);
     
     // TODO: FIXME: support reload.
     fast_cache = _srs_config->get_vhost_http_remux_fast_cache(req->vhost);
diff --git a/trunk/src/app/srs_app_ingest.cpp b/trunk/src/app/srs_app_ingest.cpp
index 0565445f3..dbbe59628 100644
--- a/trunk/src/app/srs_app_ingest.cpp
+++ b/trunk/src/app/srs_app_ingest.cpp
@@ -105,7 +105,7 @@ SrsIngester::SrsIngester()
     
     expired = false;
     
-    trd = NULL;
+    trd = new SrsDummyCoroutine();
     pprint = SrsPithyPrint::create_ingester();
 }
 
@@ -141,7 +141,7 @@ int SrsIngester::start()
     
     // start thread to run all encoding engines.
     srs_freep(trd);
-    trd = new SrsCoroutine("ingest", this, _srs_context->get_id());
+    trd = new SrsSTCoroutine("ingest", this, _srs_context->get_id());
     if ((ret = trd->start()) != ERROR_SUCCESS) {
         srs_error("st_thread_create failed. ret=%d", ret);
         return ret;
diff --git a/trunk/src/app/srs_app_kafka.cpp b/trunk/src/app/srs_app_kafka.cpp
index 6f435cc2b..7d4e103ef 100644
--- a/trunk/src/app/srs_app_kafka.cpp
+++ b/trunk/src/app/srs_app_kafka.cpp
@@ -365,7 +365,7 @@ SrsKafkaProducer::SrsKafkaProducer()
     metadata_expired = srs_cond_new();
     
     lock = srs_mutex_new();
-    trd = NULL;
+    trd = new SrsDummyCoroutine();
     worker = new SrsAsyncCallWorker();
     cache = new SrsKafkaCache();
     
@@ -410,7 +410,7 @@ int SrsKafkaProducer::start()
     }
     
     srs_freep(trd);
-    trd = new SrsCoroutine("kafka", this, _srs_context->get_id());
+    trd = new SrsSTCoroutine("kafka", this, _srs_context->get_id());
     if ((ret = trd->start()) != ERROR_SUCCESS) {
         srs_error("start kafka thread failed. ret=%d", ret);
     }
diff --git a/trunk/src/app/srs_app_listener.cpp b/trunk/src/app/srs_app_listener.cpp
index d2ef6512a..a3e5db8b0 100755
--- a/trunk/src/app/srs_app_listener.cpp
+++ b/trunk/src/app/srs_app_listener.cpp
@@ -80,7 +80,7 @@ SrsUdpListener::SrsUdpListener(ISrsUdpHandler* h, string i, int p)
     nb_buf = SRS_UDP_MAX_PACKET_SIZE;
     buf = new char[nb_buf];
     
-    trd = NULL;
+    trd = new SrsDummyCoroutine();
 }
 
 SrsUdpListener::~SrsUdpListener()
@@ -140,7 +140,7 @@ int SrsUdpListener::listen()
     srs_verbose("st open socket success. ep=%s:%d, fd=%d", ip.c_str(), port, _fd);
     
     srs_freep(trd);
-    trd = new SrsCoroutine("udp", this);
+    trd = new SrsSTCoroutine("udp", this);
     if ((ret = trd->start()) != ERROR_SUCCESS) {
         srs_error("st_thread_create listen thread error. ep=%s:%d, ret=%d", ip.c_str(), port, ret);
         return ret;
@@ -187,7 +187,7 @@ SrsTcpListener::SrsTcpListener(ISrsTcpHandler* h, string i, int p)
     _fd = -1;
     _stfd = NULL;
     
-    trd = NULL;
+    trd = new SrsDummyCoroutine();
 }
 
 SrsTcpListener::~SrsTcpListener()
@@ -242,7 +242,7 @@ int SrsTcpListener::listen()
     srs_verbose("st open socket success. ep=%s:%d, fd=%d", ip.c_str(), port, _fd);
     
     srs_freep(trd);
-    trd = new SrsCoroutine("tcp", this);
+    trd = new SrsSTCoroutine("tcp", this);
     if ((ret = trd->start()) != ERROR_SUCCESS) {
         srs_error("st_thread_create listen thread error. ep=%s:%d, ret=%d", ip.c_str(), port, ret);
         return ret;
diff --git a/trunk/src/app/srs_app_ng_exec.cpp b/trunk/src/app/srs_app_ng_exec.cpp
index e132b2f2f..371ac64d8 100644
--- a/trunk/src/app/srs_app_ng_exec.cpp
+++ b/trunk/src/app/srs_app_ng_exec.cpp
@@ -38,7 +38,7 @@ using namespace std;
 
 SrsNgExec::SrsNgExec()
 {
-    trd = NULL;
+    trd = new SrsDummyCoroutine();
     pprint = SrsPithyPrint::create_exec();
 }
 
@@ -61,7 +61,7 @@ int SrsNgExec::on_publish(SrsRequest* req)
     
     // start thread to run all processes.
     srs_freep(trd);
-    trd = new SrsCoroutine("encoder", this, _srs_context->get_id());
+    trd = new SrsSTCoroutine("encoder", this, _srs_context->get_id());
     if ((ret = trd->start()) != ERROR_SUCCESS) {
         srs_error("st_thread_create failed. ret=%d", ret);
         return ret;
diff --git a/trunk/src/app/srs_app_recv_thread.cpp b/trunk/src/app/srs_app_recv_thread.cpp
index b24ffd1f9..bc7768902 100644
--- a/trunk/src/app/srs_app_recv_thread.cpp
+++ b/trunk/src/app/srs_app_recv_thread.cpp
@@ -61,7 +61,7 @@ SrsRecvThread::SrsRecvThread(ISrsMessagePumper* p, SrsRtmpServer* r, int tm)
     rtmp = r;
     pumper = p;
     timeout = tm;
-    trd = NULL;
+    trd = new SrsDummyCoroutine();
 }
 
 SrsRecvThread::~SrsRecvThread()
@@ -77,7 +77,7 @@ int SrsRecvThread::cid()
 int SrsRecvThread::start()
 {
     srs_freep(trd);
-    trd = new SrsCoroutine("recv", this);
+    trd = new SrsSTCoroutine("recv", this);
     return trd->start();
 }
 
@@ -535,7 +535,7 @@ SrsHttpRecvThread::SrsHttpRecvThread(SrsResponseOnlyHttpConn* c)
 {
     conn = c;
     error = ERROR_SUCCESS;
-    trd = new SrsCoroutine("http-receive", this, _srs_context->get_id());
+    trd = new SrsSTCoroutine("http-receive", this, _srs_context->get_id());
 }
 
 SrsHttpRecvThread::~SrsHttpRecvThread()
diff --git a/trunk/src/app/srs_app_rtsp.cpp b/trunk/src/app/srs_app_rtsp.cpp
index d0f83b2cb..135ca9aa8 100644
--- a/trunk/src/app/srs_app_rtsp.cpp
+++ b/trunk/src/app/srs_app_rtsp.cpp
@@ -195,7 +195,7 @@ SrsRtspConn::SrsRtspConn(SrsRtspCaster* c, srs_netfd_t fd, std::string o)
     stfd = fd;
     skt = new SrsStSocket();
     rtsp = new SrsRtspStack(skt);
-    trd = new SrsCoroutine("rtsp", this);
+    trd = new SrsSTCoroutine("rtsp", this);
     
     req = NULL;
     sdk = NULL;
diff --git a/trunk/src/app/srs_app_server.cpp b/trunk/src/app/srs_app_server.cpp
index f54e1e310..5788b2fa1 100644
--- a/trunk/src/app/srs_app_server.cpp
+++ b/trunk/src/app/srs_app_server.cpp
@@ -362,7 +362,7 @@ SrsSignalManager::SrsSignalManager(SrsServer* s)
     
     server = s;
     sig_pipe[0] = sig_pipe[1] = -1;
-    trd = new SrsCoroutine("signal", this);
+    trd = new SrsSTCoroutine("signal", this);
     signal_read_stfd = NULL;
 }
 
diff --git a/trunk/src/app/srs_app_st.cpp b/trunk/src/app/srs_app_st.cpp
index c3e34e3cc..f92becc78 100755
--- a/trunk/src/app/srs_app_st.cpp
+++ b/trunk/src/app/srs_app_st.cpp
@@ -40,7 +40,46 @@ ISrsCoroutineHandler::~ISrsCoroutineHandler()
 {
 }
 
-SrsCoroutine::SrsCoroutine(const string& n, ISrsCoroutineHandler* h, int cid)
+SrsCoroutine::SrsCoroutine()
+{
+}
+
+SrsCoroutine::~SrsCoroutine()
+{
+}
+
+SrsDummyCoroutine::SrsDummyCoroutine()
+{
+}
+
+SrsDummyCoroutine::~SrsDummyCoroutine()
+{
+}
+
+int SrsDummyCoroutine::start()
+{
+    return ERROR_THREAD_DUMMY;
+}
+
+void SrsDummyCoroutine::stop()
+{
+}
+
+void SrsDummyCoroutine::interrupt()
+{
+}
+
+int SrsDummyCoroutine::pull()
+{
+    return ERROR_THREAD_DUMMY;
+}
+
+int SrsDummyCoroutine::cid()
+{
+    return 0;
+}
+
+SrsSTCoroutine::SrsSTCoroutine(const string& n, ISrsCoroutineHandler* h, int cid)
 {
     name = n;
     handler = h;
@@ -50,12 +89,12 @@ SrsCoroutine::SrsCoroutine(const string& n, ISrsCoroutineHandler* h, int cid)
     started = interrupted = disposed = false;
 }
 
-SrsCoroutine::~SrsCoroutine()
+SrsSTCoroutine::~SrsSTCoroutine()
 {
     stop();
 }
 
-int SrsCoroutine::start()
+int SrsSTCoroutine::start()
 {
     int ret = ERROR_SUCCESS;
     
@@ -77,7 +116,7 @@ int SrsCoroutine::start()
     return ret;
 }
 
-void SrsCoroutine::stop()
+void SrsSTCoroutine::stop()
 {
     if (!started || disposed) {
         return;
@@ -101,7 +140,7 @@ void SrsCoroutine::stop()
     return;
 }
 
-void SrsCoroutine::interrupt()
+void SrsSTCoroutine::interrupt()
 {
     if (!started || interrupted) {
         return;
@@ -113,17 +152,17 @@ void SrsCoroutine::interrupt()
     st_thread_interrupt((st_thread_t)trd);
 }
 
-int SrsCoroutine::pull()
+int SrsSTCoroutine::pull()
 {
     return err;
 }
 
-int SrsCoroutine::cid()
+int SrsSTCoroutine::cid()
 {
     return context;
 }
 
-int SrsCoroutine::cycle()
+int SrsSTCoroutine::cycle()
 {
     if (_srs_context) {
         if (context) {
@@ -139,9 +178,9 @@ int SrsCoroutine::cycle()
     return ret;
 }
 
-void* SrsCoroutine::pfn(void* arg)
+void* SrsSTCoroutine::pfn(void* arg)
 {
-    SrsCoroutine* p = (SrsCoroutine*)arg;
+    SrsSTCoroutine* p = (SrsSTCoroutine*)arg;
     void*res = (void*)(uint64_t)p->cycle();
     return res;
 }
diff --git a/trunk/src/app/srs_app_st.hpp b/trunk/src/app/srs_app_st.hpp
index 2d151f06e..480349181 100644
--- a/trunk/src/app/srs_app_st.hpp
+++ b/trunk/src/app/srs_app_st.hpp
@@ -67,6 +67,39 @@ public:
     virtual int cycle() = 0;
 };
 
+/**
+ * The corotine object.
+ */
+class SrsCoroutine
+{
+public:
+    SrsCoroutine();
+    virtual ~SrsCoroutine();
+public:
+    virtual int start() = 0;
+    virtual void stop() = 0;
+    virtual void interrupt() = 0;
+    virtual int pull() = 0;
+    virtual int cid() = 0;
+};
+
+/**
+ * An empty coroutine, user can default to this object before create any real coroutine.
+ * @see https://github.com/ossrs/srs/pull/908
+ */
+class SrsDummyCoroutine : public SrsCoroutine
+{
+public:
+    SrsDummyCoroutine();
+    virtual ~SrsDummyCoroutine();
+public:
+    virtual int start();
+    virtual void stop();
+    virtual void interrupt();
+    virtual int pull();
+    virtual int cid();
+};
+
 /**
  * A ST-coroutine is a lightweight thread, just like the goroutine.
  * But the goroutine maybe run on different thread, while ST-coroutine only
@@ -81,7 +114,7 @@ public:
  * @remark We always create joinable thread, so we must join it or memory leak,
  *      Please read https://github.com/ossrs/srs/issues/78
  */
-class SrsCoroutine
+class SrsSTCoroutine : public SrsCoroutine
 {
 private:
     std::string name;
@@ -97,8 +130,8 @@ private:
 public:
     // Create a thread with name n and handler h.
     // @remark User can specify a cid for thread to use, or we will allocate a new one.
-    SrsCoroutine(const std::string& n, ISrsCoroutineHandler* h, int cid = 0);
-    virtual ~SrsCoroutine();
+    SrsSTCoroutine(const std::string& n, ISrsCoroutineHandler* h, int cid = 0);
+    virtual ~SrsSTCoroutine();
 public:
     /**
      * Start the thread.
diff --git a/trunk/src/app/srs_app_thread.cpp b/trunk/src/app/srs_app_thread.cpp
index 4839c3586..1db664707 100755
--- a/trunk/src/app/srs_app_thread.cpp
+++ b/trunk/src/app/srs_app_thread.cpp
@@ -32,7 +32,7 @@ using namespace std;
 SrsCoroutineManager::SrsCoroutineManager()
 {
     cond = srs_cond_new();
-    trd = new SrsCoroutine("manager", this);
+    trd = new SrsSTCoroutine("manager", this);
 }
 
 SrsCoroutineManager::~SrsCoroutineManager()
diff --git a/trunk/src/kernel/srs_kernel_error.hpp b/trunk/src/kernel/srs_kernel_error.hpp
index c3fb41f4c..8149f4343 100644
--- a/trunk/src/kernel/srs_kernel_error.hpp
+++ b/trunk/src/kernel/srs_kernel_error.hpp
@@ -106,6 +106,7 @@
 #define ERROR_THREAD_DISPOSED               1069
 #define ERROR_THREAD_INTERRUPED             1070
 #define ERROR_THREAD_TERMINATED             1071
+#define ERROR_THREAD_DUMMY                  1072
 
 ///////////////////////////////////////////////////////
 // RTMP protocol error.