c - 避免 GLib 内存池和 Valgrind 可能在 C 中丢失

Question

由于memory pools (g_slice)，我的代码可能丢失了。我的问题是:我可以在我的代码中做些什么来避免泄漏，还是这纯粹是一个 GLib 问题？

所有这些都被报告为“可能丢失”。

==2552== 
==2552== 744 bytes in 3 blocks are possibly lost in loss record 6 of 8
==2552==    at 0x40235BE: memalign (vg_replace_malloc.c:694)
==2552==    by 0x402361B: posix_memalign (vg_replace_malloc.c:835)
==2552==    by 0x408693E: ??? (in /usr/lib/libglib-2.0.so.0.1600.6)
==2552==    by 0x4088112: g_slice_alloc (in /usr/lib/libglib-2.0.so.0.1600.6)
==2552==    by 0x405B503: ??? (in /usr/lib/libglib-2.0.so.0.1600.6)
==2552==    by 0x804876C: add_inv (in /home/user/a.out)
==2552==    by 0x8048818: main (in /home/user/a.out)

---

#include <glib.h>
static GHashTable *hashtable1;
static GHashTable *hashtable2;

int add_inv (char *a, char *b) {
  GHashTable *table = NULL;
  gpointer old_value;
  char *mykey = NULL;
  int i, plus, *pointer;

  for (i = 0; i < 2; i++)
    {
      if (i == 0)
        {
          table = hashtable1;
          mykey = a;
        }
      else if (i == 1)
        {
          table = hashtable2;
          mykey = b;
        }
      old_value = g_hash_table_lookup (table, mykey);
      if (old_value != NULL)
        {
          pointer = (int *) old_value;
          plus = *pointer + 10;
        }
      else
        plus = 10;

      pointer = g_malloc (sizeof (int));
      *pointer = plus;
      g_hash_table_replace (table, g_strdup (mykey), pointer);
    }
}

int main () {
  int i;
  hashtable1 = g_hash_table_new_full (g_str_hash, g_str_equal, (GDestroyNotify) g_free, g_free);
  hashtable2 = g_hash_table_new_full (g_str_hash, g_str_equal, (GDestroyNotify) g_free, g_free);

  for (i = 0; i < 20; i++)
    {
      char *a = g_strdup ("val1");
      char *b = g_strdup ("val2");
      add_inv (a, b);
      g_free (a);
      g_free (b);
    }
  g_hash_table_destroy (hashtable1);
  g_hash_table_destroy (hashtable2);
  return 0;
}

Answer 1

设置 G_SLICE 环境变量以重新配置 GSlice 内存分配器。

G_SLICE=always-malloc ./your_application

这里是GLib documentation的相关部分.

This will cause all slices allocated through g_slice_alloc() and released by g_slice_free1() to be actually allocated via direct calls to g_malloc() and g_free(). This is most useful for memory checkers and similar programs that use Bohem GC alike algorithms to produce more accurate results. It can also be in conjunction with debugging features of the system's malloc implementation such as glibc's MALLOC_CHECK_=2 to debug erroneous slice allocation code, allthough debug-blocks usually is a better suited debugging tool.