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线程池是一种优化多线程应用程序性能的技术。在多线程编程中，频繁创建和销毁线程会导致系统资源消耗增加。通过在后续任务启动前复用之前创建的线程，线程池能够显著降低资源浪费。GLib线程池提供了一套功能丰富的API，支持任务_submission、线程管理以及任务排序等操作。
线程池的内部数据结构由以下三个成员变量组成：
struct GThreadPool { GFunc func; // 线程执行的函数指针 gpointer user_data; // 线程任务的用户数据 gboolean exclusive; // 线程池是否为独占线程池}; 线程池提供了多个函数来管理线程池：
GThreadPool * g_thread_pool_new()gboolean g_thread_pool_push()gboolean g_thread_pool_set_max_threads()gint g_thread_pool_get_max_threads()guint g_thread_pool_get_num_threads()guint g_thread_pool_unprocessed()void g_thread_pool_free()void g_thread_pool_set_max_unused_threads()gint g_thread_pool_get_max_unused_threads()guint g_thread_pool_get_num_unused_threads()void g_thread_pool_stop_unused_threads()void g_thread_pool_set_sort_function()guint g_thread_pool_get_max_idle_time()gboolean g_thread_pool_move_to_front()GThreadPool * g_thread_pool_new()void g_thread_pool_free()gboolean g_thread_pool_push()gint g_thread_pool_get_max_threads()guint g_thread_pool_get_num_threads()gint g_thread_pool_get_max_unused_threads()guint g_thread_pool_get_num_unused_threads()guint g_thread_pool_get_max_idle_time()guint g_thread_pool_unprocessed()gboolean g_thread_pool_set_max_threads()void g_thread_pool_set_max_unused_threads()void g_thread_pool_set_max_idle_time()gboolean g_thread_pool_move_to_front()void g_thread_pool_set_sort_function()void g_thread_pool_stop_unused_threads()使用线程池的步骤如下示例：
#includestatic void test_thread_pool_func(gpointer data, gpointer user_data) { g_print("get data: %d ", GPOINTER_TO_INT(data));}void test_thread_pool_push(void) { GThreadPool *pool = NULL; GError *error = NULL; potv *pool = g_thread_pool_new(test_thread_pool_func, NULL, 4, FALSE, &error); if (!pool) { g_error(" unable to create thread pool"); return; } if (g_thread_pool_push(pool, GINT_TO_POINTER(99))) { g_print("successfull pushed task"); } else { g_print(" failed to push task"); } g_thread_pool_free(pool, TRUE, TRUE);}int main(int argc, char **argv) { test_thread_pool_push(); return 0;}
运行结果显示任务已成功提交到线程池执行。
编写一个任务处理函数，使线程池能够处理多种任务：
#includetypedef int (*foobar_method)(int a, int b);typedef struct { int foo; int bar; foobar_method func;} foobar_t;static int test_foobar_add(int a, int b) { return a + b;}static int test_foobar_multi(int a, int b) { return a * b;}static void test_thread_pool_func(gpointer data, gpointer user_data) { foobar_t *foobar = (foobar_t *)data; if (!foobar) { return; } int ret_val = foobar->func(foobar->foo, foobar->bar); g_print("ret_val: %d", ret_val); g_free(foobar);}gpointer test_thread_func(gpointer data) { foobar_t *foobar = g_new(foobar_t, 1); foobar->foo = 2; foobar->bar = 3; foobar->func = test_foobar_add; g_thread_pool_push(data, (gpointer)foobar); // 重置数据并设置不同的函数 foobar->foo = 2; foobar->bar = 3; foobar->func = test_foobar_multi; g_thread_pool_push(data, (gpointer)foobar); g_free(foobar); return NULL;}void test_thread_pool(void) { GError *error = NULL; GThread *thd = NULL; GThreadPool *pool = g_thread_pool_new(test_thread_pool_func, NULL, 4, True, &error); if (!pool) { g_error(" unable to create thread pool"); return; } thd = g_thread_new("test-thread", test_thread_func, pool); g_thread_join(thd); g_thread_pool_free(pool, TRUE, TRUE);}int main(int argc, char **argv) { test_thread_pool(); return 0;}
运行结果表明不同的函数已经在不同的线程中正确执行。
使用g_thread_pool_set_max_threads可以设置线程池的最大线程数：
#includestatic void test_thread_pool_func(gpointer data, gpointer user_data) { g_print("tid %ld: get data: %d ", (longlong)pthread_self(), GPOINTER_TO_INT(data)); sleep(1); if (GPOINTER_TO_INT(data) == TEST_THREAD_POOL_FIN) { g_print("theadpool free "); g_thread_pool_free(g_pool, TRUE, TRUE); }}gpointer test_thread_func(gpointer data) { GThreadPool *pool = (GThreadPool *)data; if (!pool) return NULL; // 设置最大线程数为0以测试设置 g_thread_pool_set_max_threads(pool, 0, NULL); sleep(1); // 重新设置为4 g_thread_pool_set_max_threads(pool, 4, NULL); // 发送多个任务 g_thread_pool_push(pool, GINT_TO_POINTER(99)); g_thread_pool_push(pool, GINT_TO_POINTER(100)); sleep(1); return NULL;}void test_thread_pool(void) { GError *error = NULL; GThread *thd = NULL; GThreadPool *pool = g_thread_pool_new(test_thread_pool_func, NULL, 4, TRUE, &error); sleep(1); thd = g_thread_new("test-thread", test_thread_func, pool); sleep(1); g_thread_join(thd); g_thread_pool_free(pool, TRUE, TRUE);}int main(int argc, char **argv) { test_thread_pool(); return 0;}
运行结果表明线程池在成功设置最大线程数后，能够正确管理线程数。
使用g_thread_pool_set_sort_function可以自定义任务排序：
#includestatic int _test_thread_int_cmp_func(gconstpointer a, gconstpointer b, gpointer user_data) { return GPOINTER_TO_INT(a) - GPOINTER_TO_INT(b);}static void test_thread_pool_func(gpointer data, gpointer user_data) { g_print("tid %ld: get data: %d ", (longlong)pthread_self(), GPOINTER_TO_INT(data)); sleep(1); if (GPOINTER_TO_INT(data) == TEST_THREAD_POOL_FIN) { g_print("theadpool free "); g_thread_pool_free(g_pool, TRUE, TRUE); }}gpointer test_thread_func(gpointer data) { GThreadPool *pool = (GThreadPool *)data; if (!pool) return NULL; // 设置线程池为1个线程 g_thread_pool_set_max_threads(pool, 1, NULL); sleep(1); // 不同的任务使用相同线程 g_thread_pool_set_sort_function(pool, _test_thread_int_cmp_func, NULL); // 发送多个任务 g_thread_pool_push(pool, GINT_TO_POINTER(99)); g_thread_pool_push(pool, GINT_TO_POINTER(120)); g_thread_pool_push(pool, GINT_TO_POINTER(101)); g_thread_pool_push(pool, GINT_TO_POINTER(106)); g_thread_pool_push(pool, GINT_TO_POINTER(203)); g_thread_pool_push(pool, GINT_TO_POINTER(104)); return NULL;}void test_thread_pool(void) { GError *error = NULL; GThread *thd = NULL; GThreadPool *pool = g_thread_pool_new(test_thread_pool_func, NULL, 1, TRUE, &error); sleep(1); thd = g_thread_new("test-thread", test_thread_func, pool); sleep(1); g_thread_join(thd); g_thread_pool_free(pool, TRUE, TRUE);}int main(int argc, char **argv) { test_thread_pool(); return 0;}
运行结果表明排序函数能够按照指定的顺序执行任务。
GLib线程池为开发人员提供了一个高效且灵活的工具来管理多线程任务。通过合理设置线程池参数，可以优化应用程序的性能表现，同时通过自定义排序函数实现任务执行订单的需求。
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