since: 2.64


interface Gio.MemoryMonitor : Gio.Initable

GMemoryMonitor will monitor system memory and suggest to the application when to free memory so as to leave more room for other applications. It is implemented on Linux using the Low Memory Monitor (API documentation).

There is also an implementation for use inside Flatpak sandboxes.

Possible actions to take when the signal is received are:

  • Free caches
  • Save files that haven’t been looked at in a while to disk, ready to be reopened when needed
  • Run a garbage collection cycle
  • Try and compress fragmented allocations
  • Exit on idle if the process has no reason to stay around
  • Call malloc_trim(3) to return cached heap pages to the kernel (if supported by your libc)

Note that some actions may not always improve system performance, and so should be profiled for your application. malloc_trim(), for example, may make future heap allocations slower (due to releasing cached heap pages back to the kernel).

See GMemoryMonitorWarningLevel for details on the various warning levels.

static void
warning_cb (GMemoryMonitor *m, GMemoryMonitorWarningLevel level)
  g_debug ("Warning level: %d", level);
    drop_caches ();

static GMemoryMonitor *
monitor_low_memory (void)
  GMemoryMonitor *m;
  m = g_memory_monitor_dup_default ();
  g_signal_connect (G_OBJECT (m), "low-memory-warning",
                    G_CALLBACK (warning_cb), NULL);
  return m;

Don’t forget to disconnect the GMemoryMonitor::low-memory-warning signal, and unref the GMemoryMonitor itself when exiting.

Available since: 2.64


In order to implement MemoryMonitor, your type must inherit fromGInitable.



Gets a reference to the default GMemoryMonitor for the system.

since: 2.64



Emitted when the system is running low on free memory. The signal handler should then take the appropriate action depending on the warning level. See the GMemoryMonitorWarningLevel documentation for details.

since: 2.64

Interface structure

struct GioMemoryMonitorInterface {
  void (* low_memory_warning) (
    GMemoryMonitor* monitor,
    GMemoryMonitorWarningLevel level

The virtual function table for GMemoryMonitor.

Interface members
void (* low_memory_warning) (
    GMemoryMonitor* monitor,
    GMemoryMonitorWarningLevel level
 No description available.

Virtual methods

No description available.