diff --git a/README.md b/README.md
index 9bbbfc2cd..5de795541 100755
--- a/README.md
+++ b/README.md
@@ -176,6 +176,7 @@ The ports used by SRS:
 
 ## V4 changes
 
+* v4.0, 2021-05-08, Refine global or thread-local variables initialize. 4.0.104
 * v4.0, 2021-05-07, RTC: Support circuit breaker. 4.0.103
 * v4.0, 2021-05-07, RTC: Refine play stream find track. 4.0.102
 * v4.0, 2021-05-07, RTC: Refine FastTimer to fixed interval. 4.0.101
diff --git a/trunk/src/app/srs_app_hybrid.cpp b/trunk/src/app/srs_app_hybrid.cpp
index e398b0222..9e0079a75 100644
--- a/trunk/src/app/srs_app_hybrid.cpp
+++ b/trunk/src/app/srs_app_hybrid.cpp
@@ -208,10 +208,11 @@ SrsServer* SrsServerAdapter::instance()
 
 SrsHybridServer::SrsHybridServer()
 {
-    // Note that the timer depends on other global variables,
-    // so we MUST never create it in constructor.
-    timer20ms_ = NULL;
-    timer5s_ = NULL;
+    // Create global shared timer.
+    timer20ms_ = new SrsFastTimer("hybrid", 20 * SRS_UTIME_MILLISECONDS);
+    timer100ms_ = new SrsFastTimer("hybrid", 100 * SRS_UTIME_MILLISECONDS);
+    timer1s_ = new SrsFastTimer("hybrid", 1 * SRS_UTIME_SECONDS);
+    timer5s_ = new SrsFastTimer("hybrid", 5 * SRS_UTIME_SECONDS);
 
     clock_monitor_ = new SrsClockWallMonitor();
 }
@@ -219,7 +220,10 @@ SrsHybridServer::SrsHybridServer()
 SrsHybridServer::~SrsHybridServer()
 {
     srs_freep(clock_monitor_);
+
     srs_freep(timer20ms_);
+    srs_freep(timer100ms_);
+    srs_freep(timer1s_);
     srs_freep(timer5s_);
 
     vector<ISrsHybridServer*>::iterator it;
@@ -239,17 +243,6 @@ srs_error_t SrsHybridServer::initialize()
 {
     srs_error_t err = srs_success;
 
-    // init st
-    if ((err = srs_st_init()) != srs_success) {
-        return srs_error_wrap(err, "initialize st failed");
-    }
-
-    // Create global shared timer.
-    timer20ms_ = new SrsFastTimer("hybrid", 20 * SRS_UTIME_MILLISECONDS);
-    timer100ms_ = new SrsFastTimer("hybrid", 100 * SRS_UTIME_MILLISECONDS);
-    timer1s_ = new SrsFastTimer("hybrid", 1 * SRS_UTIME_SECONDS);
-    timer5s_ = new SrsFastTimer("hybrid", 5 * SRS_UTIME_SECONDS);
-
     // Start the timer first.
     if ((err = timer20ms_->start()) != srs_success) {
         return srs_error_wrap(err, "start timer");
@@ -478,5 +471,5 @@ srs_error_t SrsHybridServer::on_timer(srs_utime_t interval)
     return err;
 }
 
-SrsHybridServer* _srs_hybrid = new SrsHybridServer();
+SrsHybridServer* _srs_hybrid = NULL;
 
diff --git a/trunk/src/app/srs_app_threads.cpp b/trunk/src/app/srs_app_threads.cpp
index 77ee3d1b7..c81a07b52 100644
--- a/trunk/src/app/srs_app_threads.cpp
+++ b/trunk/src/app/srs_app_threads.cpp
@@ -83,12 +83,12 @@ srs_error_t SrsCircuitBreaker::initialize()
 
 bool SrsCircuitBreaker::hybrid_high_water_level()
 {
-    return enabled_ && hybrid_critical_water_level() || hybrid_high_water_level_;
+    return enabled_ && (hybrid_critical_water_level() || hybrid_high_water_level_);
 }
 
 bool SrsCircuitBreaker::hybrid_critical_water_level()
 {
-    return enabled_ && hybrid_dying_water_level() || hybrid_critical_water_level_;
+    return enabled_ && (hybrid_dying_water_level() || hybrid_critical_water_level_);
 }
 
 bool SrsCircuitBreaker::hybrid_dying_water_level()
@@ -133,7 +133,7 @@ srs_error_t SrsCircuitBreaker::on_timer(srs_utime_t interval)
     // The hybrid thread cpu and memory.
     float thread_percent = stat->percent * 100;
 
-    if (enabled_ && hybrid_high_water_level() || hybrid_critical_water_level() || _srs_pps_snack2->r10s()) {
+    if (enabled_ && (hybrid_high_water_level() || hybrid_critical_water_level() || _srs_pps_snack2->r10s())) {
         srs_trace("CircuitBreaker: cpu=%.2f%%,%dMB, break=%d,%d,%d, cond=%.2f%%, snk=%d,%d,%d",
             u->percent * 100, memory,
             hybrid_high_water_level(), hybrid_critical_water_level(), hybrid_dying_water_level(), // Whether Circuit-Break is enable.
@@ -147,3 +147,17 @@ srs_error_t SrsCircuitBreaker::on_timer(srs_utime_t interval)
 
 SrsCircuitBreaker* _srs_circuit_breaker = new SrsCircuitBreaker();
 
+srs_error_t srs_thread_initialize()
+{
+    srs_error_t err = srs_success;
+
+    // init st
+    if ((err = srs_st_init()) != srs_success) {
+        return srs_error_wrap(err, "initialize st failed");
+    }
+
+    _srs_hybrid = new SrsHybridServer();
+
+    return err;
+}
+
diff --git a/trunk/src/app/srs_app_threads.hpp b/trunk/src/app/srs_app_threads.hpp
index 7e293b6fb..57fe7cbfb 100644
--- a/trunk/src/app/srs_app_threads.hpp
+++ b/trunk/src/app/srs_app_threads.hpp
@@ -63,5 +63,8 @@ private:
 
 extern SrsCircuitBreaker* _srs_circuit_breaker;
 
+// Initialize global or thread-local variables.
+extern srs_error_t srs_thread_initialize();
+
 #endif
 
diff --git a/trunk/src/core/srs_core_version4.hpp b/trunk/src/core/srs_core_version4.hpp
index 7d3af0f74..56062eeec 100644
--- a/trunk/src/core/srs_core_version4.hpp
+++ b/trunk/src/core/srs_core_version4.hpp
@@ -26,6 +26,6 @@
 
 #define VERSION_MAJOR       4
 #define VERSION_MINOR       0
-#define VERSION_REVISION    103
+#define VERSION_REVISION    104
 
 #endif
diff --git a/trunk/src/main/srs_main_server.cpp b/trunk/src/main/srs_main_server.cpp
index fd0fe5804..727c41b45 100644
--- a/trunk/src/main/srs_main_server.cpp
+++ b/trunk/src/main/srs_main_server.cpp
@@ -87,6 +87,11 @@ SrsServer* _srs_server = NULL;
 srs_error_t do_main(int argc, char** argv)
 {
     srs_error_t err = srs_success;
+
+    // Initialize global or thread-local variables.
+    if ((err = srs_thread_initialize()) != srs_success) {
+        return srs_error_wrap(err, "thread init");
+    }
     
     // TODO: support both little and big endian.
     srs_assert(srs_is_little_endian());