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![Drawbacks of Ref counter ● Cyclic reference: ○ Self reference objects ○ Count will never decrease to zero. ○ It always be a unused objects. <python> a = [5] a.append(a) </python> ● ‘Del’ keyword in python. ● Refer: Link](https://image.slidesharecdn.com/garbagecollectorinpython-210301052328/75/Garbage-collector-in-python-8-2048.jpg)
Uploaded byIbrahim Kasim
Garbage collector in python
The document explains garbage collection (gc) in Python, detailing its purpose as automatic memory management to reclaim memory from unused objects. It discusses key concepts such as Python core objects (pyobj), memory references, and reference counting, along with the drawbacks of reference counting like cyclic references. Additionally, it outlines the implementation of a generational garbage collection system and mentions other implementations of gc like PyPy and Jython.
Garbage collector in python
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- 2. About Me ★ Workingin python, django, js > 6years ★ Github: github.com/ibrahimsha23 ★ Linkedin: in/ibrahimshak
- 3. GC Definition Definition(wiki) ● garbagecollection (GC) is a form of automatic memory management. The garbage collector, or just collector, attempts to reclaim garbage, or memory occupied by objects that are no longer in use by the program. Purpose: ● Freed the memory block of unwanted objects in python.
- 4. Prerequisites of GC Toknow the gc module implementation in CPython, we need to understand few elements, ➢ Pyobj (Python Core Object) ➢ Memory reference ➢ Reference counter
- 5. Pyobj ● Pyobj isthe python core object. ● All objects in python, finally referred as pyobj. ● Pyobj has three properties, ○ Type ○ Value ○ Reference Counter ● If you inspect any object in python will have these properties.
- 6. Memory Reference ● Inpython, Everything is an object. ● Tag reference. ● Creating new object with same value, will not create a new malloc. ○ a=5, b=5 ○ a = 6 ● Refer: Link
- 7. Reference Counter ● Onevery allocation/ tag the memory reference of an object, will increase the ref count for the object. ● On every assignment, function call args reference count will be increased. ● On de-allocation of object, will decrease the reference count. ● When ref count leads to zero, will be removed from the memory block. ● Reference counter is one of the types of GC. ● `sys.getrefcount( )` ● Refer: Link
- 8. Drawbacks of Refcounter ● Cyclic reference: ○ Self reference objects ○ Count will never decrease to zero. ○ It always be a unused objects. <python> a = [5] a.append(a) </python> ● ‘Del’ keyword in python. ● Refer: Link
- 9. GC - Implementation ●Generational based garbage collection ○ {0, 1, 2} ● Solving cyclic reference issue. ● Enabling/Disabling garbage collection manually. ● Source: Modules/gcmodule.c ● Refer: Link ● Gen -0 -> Newly created objects ● Gen - 1 -> Live objects ● Gen -2 -> Global objects
- 10. MISC (GC) ● Pypy,jython, iron python implementation on gc. ● Instagram disabling gc.(link).
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