c - X 工具包 : heap is growing when recreating widgets

Question

我试图理解为什么以下程序会泄漏内存。当我使用命令 more /proc/<pid>/smaps 查看堆大小时，我可以看到堆只在增长。似乎 XtDestroyWidget 并没有真正释放内存。如果有人能告诉我为什么会这样并告诉我重新创建小部件的正确方法，我将不胜感激。提前致谢!

/* Compile on Solaris: cc widgets_mem.c -lXm -lXt -lX11 */
/* Compile on Linux: gcc -m32 widgets_mem.c -lXm -lXt -lX11 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/keysymdef.h>

#include <Xm/MainW.h>
#include <Xm/PushB.h>
#include <Xm/Form.h>


Widget      toplevel;
Widget      w_main;
Widget      w_bb;
Widget      w_button = NULL;

Window      root_win;
XtAppContext    app;
int     screen_number;
Display        *display = NULL;

void recreateWidgets ()
{
    printf ("recreating widgets\n");
    XtDestroyWidget (w_button);

    w_button = XtVaCreateManagedWidget (
    "button",
    xmPushButtonWidgetClass, w_bb,
    XmNfillOnArm, False,
    XmNhighlightThickness, 0,
    XmNborderWidth, 1,
    XmNmarginTop, 1,
    XmNmarginWidth, 2,
    XmNmarginHeight, 0,
    XmNwidth, 20,
    XmNheight, 10,
    XmNrecomputeSize, False,
    XmNalignment, XmALIGNMENT_CENTER,
    NULL);
}


void main (int argc, char **argv)
{
    XEvent  event;

    toplevel = XtVaAppInitialize (&app, "Mem leak test",
                  NULL, 0, &argc, argv, NULL, NULL);
    display = XtDisplay (toplevel);
    screen_number = DefaultScreen (display);
    root_win = RootWindow (display, screen_number);

    w_main = XtVaCreatePopupShell (
    "main", 
    topLevelShellWidgetClass, toplevel,
    XmNgeometry, "-0+0",
    XmNborderWidth, 0,
    XmNshadowThickness, 0,
    XmNminWidth, 1, 
    XmNmwmDecorations, 0,
    XmNmwmFunctions, 0,
    XmNwidth, 600,
    XmNheight, 200,
    NULL);

    w_bb = XtVaCreateManagedWidget (
    "",
    xmBulletinBoardWidgetClass, w_main,
    XmNborderWidth, 4,
    XmNshadowThickness, 0,
    XmNmarginWidth, 0,
    XmNmarginHeight, 0,
    XmNx, 0,
    XmNy, 0,
    XmNwidth, 500,
    XmNheight, 100,
    NULL);

    w_button = XtVaCreateManagedWidget (
    "button",
    xmPushButtonWidgetClass, w_bb,
    XmNfillOnArm, False,
    XmNhighlightThickness, 0,
    XmNborderWidth, 1,
    XmNmarginTop, 1,
    XmNmarginWidth, 2,
    XmNmarginHeight, 0,
    XmNwidth, 20,
    XmNheight, 10,
    XmNrecomputeSize, False,
    XmNalignment, XmALIGNMENT_CENTER,
    NULL);

    XtPopup (w_main, XtGrabNone);

    while (1)
    {
        XtAppNextEvent (app, &event);
        if (event.type == ButtonPress)
        {
            printf ("Button pressed, recreating widgets\n");
            recreateWidgets();
        }
    }
}

Answer 1

我在我的代码中发现了错误:我必须添加一个 XtDispatchEvent(&event)，它处理 destory 列表上的小部件的重新分配，这是 Xt 中的一个内部列表。