diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2b2a0a7..58300ea 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,8 +1,12 @@
 cmake_minimum_required(VERSION 3.0)
 
-set(CMAKE_C_STANDARD 99)
+set(CMAKE_CXX_STANDARD 11)
 
-project(tiny_thread_pool LANGUAGES C)
+project(tiny_thread_demo LANGUAGES CXX)
 
-add_executable(tiny_pool main.c tiny_pool.c)
-target_link_libraries(tiny_pool pthread)
+include_directories(src)
+
+add_subdirectory(src)
+
+add_executable(demo demo.cc)
+target_link_libraries(demo tiny_pool)
diff --git a/demo.cc b/demo.cc
new file mode 100644
index 0000000..a053e30
--- /dev/null
+++ b/demo.cc
@@ -0,0 +1,34 @@
+#include <iostream>
+#include <unistd.h>
+#include "tiny_pool.h"
+
+void demo_func(void *arg) {
+
+    std::cout << *(int*)arg << std::endl;
+
+    sleep(1);
+
+}
+
+int main() {
+    std::cout << "tiny thread pool demo start" << std::endl;
+
+
+    auto pool = tiny_pool_create(3);
+
+    int dat[] = {0, 1, 2, 3, 4, 5, 6};
+    tiny_pool_submit(pool, demo_func, (void*)&dat[0]);
+    tiny_pool_submit(pool, demo_func, (void*)&dat[1]);
+    tiny_pool_submit(pool, demo_func, (void*)&dat[2]);
+    tiny_pool_submit(pool, demo_func, (void*)&dat[3]);
+    tiny_pool_submit(pool, demo_func, (void*)&dat[4]);
+    tiny_pool_submit(pool, demo_func, (void*)&dat[5]);
+    tiny_pool_submit(pool, demo_func, (void*)&dat[6]);
+
+    tiny_pool_boot(pool);
+
+    tiny_pool_join(pool);
+
+    std::cout << "tiny thread pool demo exit" << std::endl;
+    return 0;
+}
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
new file mode 100644
index 0000000..f84f5d3
--- /dev/null
+++ b/src/CMakeLists.txt
@@ -0,0 +1,8 @@
+cmake_minimum_required(VERSION 3.0)
+
+set(CMAKE_C_STANDARD 99)
+
+project(tiny_thread_pool LANGUAGES C)
+
+add_library(tiny_pool tiny_pool.c)
+target_link_libraries(tiny_pool pthread)
diff --git a/tiny_pool.c b/src/tiny_pool.c
similarity index 94%
rename from tiny_pool.c
rename to src/tiny_pool.c
index d075cea..97e0d83 100644
--- a/tiny_pool.c
+++ b/src/tiny_pool.c
@@ -78,6 +78,7 @@ task_t* task_queue_pop(pool_t *pool) { // pop one task with blocking wait
         pthread_cond_wait(&pool->task_queue_not_empty, &pool->mutex); // wait new task added
         printf("%lu -> pop exit wait\n", pthread_self());
         if (pool->status == EXITING) {
+            pthread_mutex_unlock(&pool->mutex);
             printf("%lu -> sub thread exit from idle\n", pthread_self());
             pthread_exit(NULL); // sub thread exit at EXITING stage
         }
@@ -190,9 +191,15 @@ void free_tiny_pool(pool_t *pool) {
 
     printf("start free pool resource\n");
 
+//    pthread_mutex_unlock(&pool->mutex);
+
+//    printf("flag 1\n");
+
     pthread_cond_destroy(&pool->without_busy_thread);
     pthread_cond_destroy(&pool->task_queue_not_empty);
     pthread_cond_destroy(&pool->task_queue_empty);
+//    printf("flag 2\n");
+
     pthread_mutex_destroy(&pool->mutex);
 
     free(pool->threads);
@@ -202,6 +209,8 @@ void free_tiny_pool(pool_t *pool) {
 
 }
 
+#include <unistd.h>
+
 bool tiny_pool_join(pool_t *pool) {
     printf("start pool join\n");
 
@@ -237,11 +246,26 @@ bool tiny_pool_join(pool_t *pool) {
     pthread_mutex_unlock(&pool->mutex); // prevent other functions blocking waiting
 
     printf("start sub threads joining\n");
+
+//    for (uint32_t i = 0; i < pool->thread_num; ++i) {
+//        pthread_cond_broadcast(&pool->task_queue_not_empty); // trigger idle threads
+//        while (pthread_mutex_trylock(&pool->mutex)) {
+//            printf("try lock again\n");
+//        }
+//        pthread_mutex_unlock(&pool->mutex);
+//    }
+//
+//    printf("free threads complete\n");
+
     for (uint32_t i = 0; i < pool->thread_num; ++i) {
         pthread_cond_broadcast(&pool->task_queue_not_empty); // trigger idle threads
+        printf("start join sub thread %lu\n", pool->threads[i]);
         pthread_join(pool->threads[i], NULL);
         printf("sub thread %lu joined\n", pool->threads[i]);
     }
+
+//    sleep(10);
+
     printf("sub threads join complete\n");
 
     free_tiny_pool(pool);
diff --git a/tiny_pool.h b/src/tiny_pool.h
similarity index 98%
rename from tiny_pool.h
rename to src/tiny_pool.h
index 4ee507c..11b148c 100644
--- a/tiny_pool.h
+++ b/src/tiny_pool.h
@@ -75,6 +75,10 @@ typedef struct pool_t {
     pthread_cond_t without_busy_thread; // condition for busy thread number becomes zero
 } pool_t;
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /// This function create a new thread pool, you need to specify the number of threads,
 /// it will be in the `PREPARING` state, and return NULL on failure.
 pool_t* tiny_pool_create(uint32_t size);
@@ -104,4 +108,8 @@ void tiny_pool_detach(pool_t *pool);
 /// this will cause the interruption of running tasks and the loss of un-running tasks.
 void tiny_pool_kill(pool_t *pool);
 
+#ifdef __cplusplus
+};
+#endif
+
 #endif