diff --git a/trunk/src/app/srs_app_log.cpp b/trunk/src/app/srs_app_log.cpp
index 2ea4079c7f..0faef4fa69 100644
--- a/trunk/src/app/srs_app_log.cpp
+++ b/trunk/src/app/srs_app_log.cpp
@@ -38,13 +38,6 @@
 #include <srs_kernel_utility.hpp>
 #include <srs_app_threads.hpp>
 
-#include <srs_protocol_kbps.hpp>
-
-SrsPps* _srs_thread_sync_10us = new SrsPps();
-SrsPps* _srs_thread_sync_100us = new SrsPps();
-SrsPps* _srs_thread_sync_1000us = new SrsPps();
-SrsPps* _srs_thread_sync_plus = new SrsPps();
-
 // the max size of a line of log.
 #define LOG_MAX_SIZE 8192
 
@@ -235,24 +228,9 @@ void SrsFileLog::write_log(char *str_log, int size, int level)
         return;
     }
 
-    // It's ok to use cache, because it has been updated in generating log header.
-    srs_utime_t now = srs_get_system_time();
-
     // write log to file.
     if ((err = writer_->write(str_log, size, NULL)) != srs_success) {
         srs_error_reset(err); // Ignore any error for log writing.
     }
-
-    // Stat the sync wait of locks.
-    srs_utime_t elapsed = srs_update_system_time() - now;
-    if (elapsed <= 10) {
-        ++_srs_thread_sync_10us->sugar;
-    } else if (elapsed <= 100) {
-        ++_srs_thread_sync_100us->sugar;
-    } else if (elapsed <= 1000) {
-        ++_srs_thread_sync_1000us->sugar;
-    } else {
-        ++_srs_thread_sync_plus->sugar;
-    }
 }
 
diff --git a/trunk/src/app/srs_app_threads.cpp b/trunk/src/app/srs_app_threads.cpp
index 2a160fe16b..e8c17414d5 100644
--- a/trunk/src/app/srs_app_threads.cpp
+++ b/trunk/src/app/srs_app_threads.cpp
@@ -35,10 +35,10 @@ using namespace std;
 
 #include <srs_protocol_kbps.hpp>
 
-extern SrsPps* _srs_thread_sync_10us;
-extern SrsPps* _srs_thread_sync_100us;
-extern SrsPps* _srs_thread_sync_1000us;
-extern SrsPps* _srs_thread_sync_plus;
+SrsPps* _srs_thread_sync_10us = new SrsPps();
+SrsPps* _srs_thread_sync_100us = new SrsPps();
+SrsPps* _srs_thread_sync_1000us = new SrsPps();
+SrsPps* _srs_thread_sync_plus = new SrsPps();
 
 SrsThreadMutex::SrsThreadMutex()
 {
@@ -310,9 +310,28 @@ srs_error_t SrsAsyncFileWriter::flush()
 {
     srs_error_t err = srs_success;
 
+    // The time to wait here, is the time to wait there, because they wait for the same lock
+    // at queue to push_back or swap all messages.
+    srs_utime_t now = srs_update_system_time();
+
     vector<SrsSharedPtrMessage*> flying;
-    queue_->swap(flying);
+    if (true) {
+        queue_->swap(flying);
+    }
+
+    // Stat the sync wait of locks.
+    srs_utime_t elapsed = srs_update_system_time() - now;
+    if (elapsed <= 10) {
+        ++_srs_thread_sync_10us->sugar;
+    } else if (elapsed <= 100) {
+        ++_srs_thread_sync_100us->sugar;
+    } else if (elapsed <= 1000) {
+        ++_srs_thread_sync_1000us->sugar;
+    } else {
+        ++_srs_thread_sync_plus->sugar;
+    }
 
+    // Flush the flying messages to disk.
     for (int i = 0; i < (int)flying.size(); i++) {
         SrsSharedPtrMessage* msg = flying.at(i);