### Interface

# Gio MemoryMonitor

since: 2.64

#### Description

    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);
      if (warning_level > G_MEMORY_MONITOR_WARNING_LEVEL_LOW)
        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

#### Prerequisite

In order to implement MemoryMonitor, your type must inherit from`GInitable`.

#### Functions

###### g_memory_monitor_dup_default

Gets a reference to the default `GMemoryMonitor` for the system.

since: 2.64

#### Signals

###### Gio.MemoryMonitor::low-memory-warning

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

`low_memory_warning`

    void (* low_memory_warning) (
        GMemoryMonitor* monitor,
        GMemoryMonitorWarningLevel level
      )

| The virtual function pointer for the `GMemoryMonitor::low-memory-warning` signal.

#### Virtual methods

###### Gio.MemoryMonitor.low_memory_warning

The virtual function pointer for the `GMemoryMonitor::low-memory-warning` signal.

since: 2.0