Python in a Nutshell

Name

set_threshold

Synopsis

set_threshold(thresh0[,thresh1[,thresh2]])

Sets the thresholds that control how frequently cyclic garbage collection cycles run. If you set thresh0 to 0, garbage collection is disabled. Garbage collection is an advanced topic, and the details of the generational garbage collection approach used in Python and its thresholds are beyond the scope of this book.

When you know you have no cyclic garbage loops in your program, or when you can’t afford the delay of a cyclic garbage collection run at some crucial time, you can suspend automatic garbage collection by calling gc.disable( ). You can enable collection again later by calling gc.enable( ). You can test whether automatic collection is currently enabled by calling gc.isenabled( ), which returns True or False. To control when the time needed for collection is spent, you can call gc.collect( ) to force a full cyclic collection run to happen immediately. An idiom for wrapping some time-critical code is therefore:

import gc
gc_was_enabled = gc.isenabled( )
if gc_was_enabled:
    gc.collect( )
    gc.disable( )
# insert some time-critical code here
if gc_was_enabled:
    gc.enable( )

The other functionality in module gc is more advanced and rarely used, and can be grouped into two areas. Functions get_threshold and set_threshold and the debug flag DEBUG_STATS can help you fine-tune garbage collection to optimize your program’s performance. The rest of gc’s functionality is there to help you diagnose memory leaks in your ...