【问题标题】:Memory Leaks in GTK hello_world programGTK hello_world 程序中的内存泄漏
【发布时间】:2013-05-15 14:48:11
【问题描述】:

所以...我正在尝试从我的 GTK+ 3 程序中消除一些内存泄漏。尽管回顾一些简单的示例以查看是否有一些我忘记的清理内容是个好主意,但是文档中提供的 hello_world 程序也有泄漏。 (下面的 Valgrind 输出)。

这些泄漏是否可以接受?如果是这样,我应该使用其他应用程序来调试 GTK 程序吗?

==13717== Memcheck, a memory error detector
==13717== Copyright (C) 2002-2012, and GNU GPL'd, by Julian Seward et al.
==13717== Using Valgrind-3.8.1 and LibVEX; rerun with -h for copyright info
==13717== Command: ./a
==13717== 
Hello World
==13717== 
==13717== HEAP SUMMARY:
==13717==     in use at exit: 1,578,162 bytes in 11,614 blocks
==13717==   total heap usage: 45,699 allocs, 34,085 frees, 6,461,970 bytes allocated
==13717== 
==13717== LEAK SUMMARY:
==13717==    definitely lost: 2,560 bytes in 5 blocks
==13717==    indirectly lost: 6,656 bytes in 207 blocks
==13717==      possibly lost: 363,228 bytes in 1,937 blocks
==13717==    still reachable: 1,205,718 bytes in 9,465 blocks
==13717==         suppressed: 0 bytes in 0 blocks
==13717== Rerun with --leak-check=full to see details of leaked memory
==13717== 
==13717== For counts of detected and suppressed errors, rerun with: -v
==13717== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 2 from 2)

代码:

#include <gtk/gtk.h>

/* This is a callback function. The data arguments are ignored
 * in this example. More on callbacks below.
 */
static void
print_hello (GtkWidget *widget,
             gpointer   data)
{
  g_print ("Hello World\n");
}

static gboolean
on_delete_event (GtkWidget *widget,
                 GdkEvent  *event,
                 gpointer   data)
{
  /* If you return FALSE in the "delete_event" signal handler,
   * GTK will emit the "destroy" signal. Returning TRUE means
   * you don't want the window to be destroyed.
   *
   * This is useful for popping up 'are you sure you want to quit?'
   * type dialogs.
   */

  g_print ("delete event occurred\n");

  return TRUE;
}

int
main (int   argc,
      char *argv[])
{
  /* GtkWidget is the storage type for widgets */
  GtkWidget *window;
  GtkWidget *button;

  /* This is called in all GTK applications. Arguments are parsed
   * from the command line and are returned to the application.
   */
  gtk_init (&argc, &argv);

  /* create a new window, and set its title */
  window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
  gtk_window_set_title (GTK_WINDOW (window), "Hello");

  /* When the window emits the "delete-event" signal (which is emitted
   * by GTK+ in response to an event coming from the window manager,
   * usually as a result of clicking the "close" window control), we
   * ask it to call the on_delete_event() function as defined above.
   *
   * The data passed to the callback function is NULL and is ignored
   * in the callback function.
   */
  g_signal_connect (window, "delete-event", G_CALLBACK (on_delete_event), NULL);

  /* Here we connect the "destroy" event to the gtk_main_quit() function.
   *
   * This signal is emitted when we call gtk_widget_destroy() on the window,
   * or if we return FALSE in the "delete_event" callback.
   */
  g_signal_connect (window, "destroy", G_CALLBACK (gtk_main_quit), NULL);

  /* Sets the border width of the window. */
  gtk_container_set_border_width (GTK_CONTAINER (window), 10);

  /* Creates a new button with the label "Hello World". */
  button = gtk_button_new_with_label ("Hello World");

  /* When the button receives the "clicked" signal, it will call the
   * function print_hello() passing it NULL as its argument.
   *
   * The print_hello() function is defined above.
   */
  g_signal_connect (button, "clicked", G_CALLBACK (print_hello), NULL);

  /* The g_signal_connect_swapped() function will connect the "clicked" signal
   * of the button to the gtk_widget_destroy() function; instead of calling it
   * using the button as its argument, it will swap it with the user data
   * argument. This will cause the window to be destroyed by calling
   * gtk_widget_destroy() on the window.
   */
  g_signal_connect_swapped (button, "clicked", G_CALLBACK (gtk_widget_destroy), window);

  /* This packs the button into the window. A GtkWindow inherits from GtkBin,
   * which is a special container that can only have one child
   */
  gtk_container_add (GTK_CONTAINER (window), button);

  /* The final step is to display this newly created widget... */
  gtk_widget_show (button);

  /* ... and the window */
  gtk_widget_show (window);

  /* All GTK applications must have a gtk_main(). Control ends here
   * and waits for an event to occur (like a key press or a mouse event),
   * until gtk_main_quit() is called.
   */
  gtk_main ();

  return 0;
}

【问题讨论】:

    标签: c memory-leaks gtk valgrind


    【解决方案1】:

    此答案是根据同一问题的答案编译而成的(在现已解散的 www.gtkforums.com 上)。

    GTK+ 在分配和释放应用程序生命周期所需的内部缓冲区时非常懒惰。例如,它可以在初始化期间为查找表分配一个内存区域,这是应用程序生命周期所需的。 GTK+ 将永远不会释放它。对 Valgrind 来说,这看起来像是内存泄漏(从技术上讲确实如此),但作为一种优化,GTK+ 不会释放它,因为它将在应用程序退出期间被释放,因此不是错误。这就是为什么你需要抑制文件以便 Valgrind 可以忽略这些文件。问题是您需要在大多数 GTK+ 版本更改中更改这些内容。

    抑制文件的存储库: https://github.com/dtrebbien/GNOME.supp

    克隆存储库后,您可以使用“make”生成抑制文件(glib、gdk 等也附带),然后将 valgrind 引用到它们,如下所示:

    valgrind ./a --suppression=/path/to/gtk3.supp
    

    【讨论】:

    • 我不明白如何可靠地使用它。我使用gcc -g -Wall $(pkg-config --cflags gtk+-3.0) bill.c $(pkg-config --libs gtk+-3.0) -o bill 在问题中编译了您的代码。我构建了 dtrebbien/GNOME.supp 并将所有*supp 文件安装到/usr/lib/valgrind/ 中。我用valgrind -v --suppressions=/usr/lib/valgrind/{base,glib,gio,gdk,gtk,gtk3}.supp ./bill 运行了你的例子,valgrind 仍然显示错误。请解释更多(在 Debian/Sid/x86-64 上使用 GTK3.22,valgrind 3.12)
    【解决方案2】:

    为了调试 glib/gtk 程序,我会使用这个命令:

    G_SLICE=debug-blocks valgrind --tool=memcheck --leak-check=full <gtk program>
    

    G_SLICE=debug-blocks 将关闭 gtk 的高级内存管理以允许 valgrind 显示正确的结果。

    --leak-check=full 将显示泄漏内存块的堆栈跟踪。

    您还可以使用 --show-reachable=yes 查看程序退出时所有尚未空闲的内存块的堆栈跟踪。

    还有 massif valgrind 工具可以跟踪内存使用情况,以显示程序的哪些部分使用的内存最多。

    在地块下运行程序:

    G_SLICE=always-malloc valgrind --tool=massif --detailed-freq=2 --max-snapshots=400 --num-callers=20 <gtk program>
    

    显示结果:

    ms_print massif.out.<pid>
    

    【讨论】:

    • Valgrind 在 G_SLICE=debug-blocks 时仍然显示丢失了 2560 个块。我会看看痕迹,看看我能不能知道它们来自哪里。
    【解决方案3】:

    代替valgrind 的“泄漏消毒剂”对我有用。

    编译:

    gcc -g -fsanitize=leak `pkg-config --cflags gtk+-3.0` hello_world.c `pkg-config --libs gtk+-3.0`
    

    *注意-fsanitize=leak 选项

    运行:

    ./a.out
    

    【讨论】:

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