Memory Slices

GSlice was a space-efficient and multi-processing scalable way to allocate equal sized pieces of memory. Since GLib 2.76, its implementation has been removed and it calls g_malloc() and g_free(), because the performance of the system-default allocators has improved on all platforms since GSlice was written.

The GSlice APIs have not been deprecated, as they are widely in use and doing so would be very disruptive for little benefit.

New code should be written using g_new()/g_malloc() and g_free(). There is no particular benefit in porting existing code away from g_slice_new()/g_slice_free() unless it’s being rewritten anyway.

Here is an example for using the slice allocator:

gchar *mem[10000];
gint i;

// Allocate 10000 blocks.
for (i = 0; i < 10000; i++)
  {
    mem[i] = g_slice_alloc (50);

    // Fill in the memory with some junk.
    for (j = 0; j < 50; j++)
      mem[i][j] = i * j;
  }

// Now free all of the blocks.
for (i = 0; i < 10000; i++)
  g_slice_free1 (50, mem[i]);

And here is an example for using the using the slice allocator with data structures:

GRealArray *array;

// Allocate one block, using the g_slice_new() macro.
array = g_slice_new (GRealArray);

// We can now use array just like a normal pointer to a structure.
array->data            = NULL;
array->len             = 0;
array->alloc           = 0;
array->zero_terminated = (zero_terminated ? 1 : 0);
array->clear           = (clear ? 1 : 0);
array->elt_size        = elt_size;

// We can free the block, so it can be reused.
g_slice_free (GRealArray, array);