PythonMemory Management101 DeepinginGarbagecollector Jos Manuel - - PowerPoint PPT Presentation

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PythonMemory Management101 DeepinginGarbagecollector Jos Manuel - - PowerPoint PPT Presentation

Dec 23, 2023 108 likes •503 views

PythonMemory Management101 DeepinginGarbagecollector Jos Manuel Ortega @jmortegac Aboutme @jmortegac http://jmortega.github.io https://www.linkedin.com/in/jmortega1/ Agenda

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José Manuel Ortega @jmortegac

PythonMemory Management101

DeepinginGarbagecollector

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Aboutme

  • @jmortegac
  • http://jmortega.github.io
  • https://www.linkedin.com/in/jmortega1/
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Agenda

  • Introductiontomemorymanagement
  • Garbagecollectorandreference

countingwithpython

  • Reviewthegcmoduleforconfiguring

thepythongarbagecollector

  • Bestpracticesformemorymanagment
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Introductiontomemorymanagement

  • Memorymanagementistheprocessof

efficientlyallocating,de-allocating,and coordinatingmemorysothatallthe differentprocessesrunsmoothlyandcan

  • ptimallyaccessdifferentsystem

resources.

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PythonObjectsinMemory

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PythonMemoryManager

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Heapallocation

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def main(): x=300 print(id(x)) w=fun(x) print(id(w)) def sqr(x): print (id(x)) z=x*x print(id(z)) return z if __name__ == "__main__": main()

Heapallocation

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PythonObjectsinMemory

  • EachvariableinPythonactsasanobject
  • Pythonisadynamicallytypedlanguage

whichmeansthatwedonotneedto declaretypesforvariables.

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PythonObjectsinMemory

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PythonObjectsinMemory

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PythonObjectsinMemory

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PythonObjectsinMemory

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id()method

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id()method

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id()method

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isOperator

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Referencecounting

  • Pythonmanagesobjectsbyusingreference

counting

  • Referencecountingworksbycountingthe

numberoftimesanobjectisreferencedby

  • therobjectsintheapplication.
  • Whenreferencestoanobjectareremoved,

thereferencecountforanobjectis decremented.

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  • Areferenceisacontainerobjectpointingat

anotherobject.

  • Referencecountingisasimpletechnique

inwhichobjectsareallocatedwhenthereis referencetotheminaprogram

Referencecounting

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  • whenreferencecountincreases?

○ x=1 ○ def(x): ○ list.append(x)

Referencecounting

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Referencecounting

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Referencecounting

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Referencecounting

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  • Easytoimplement
  • Objectsareimmediatelydeletedwhen

referencecounteris0 ✗Notthread-safe ✗Doesn’tdetectcyclicreferences ✗spaceoverhead-referencecountis storedforeveryobject

Referencecounting

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Garbagecollector(GC)module

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  • ReferenceCounting+GenerationalGC
  • RefCountreacheszero,immediate

deletion

  • Deletedobjectswithcyclicreferences

aredeletedwithTracingGC

PythonGarbagecollector

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Garbagecollector(GC)referencecycle

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>>> def ref_cycle(): ... list = [1, 2, 3, 4] ... list.append(list) ... return list

Garbagecollector(GC)referencecycle

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Garbage collector(GC) reference cycle

import gc for i in range(8): ref_cycle() n = gc.collect() print("Number of unreachable objects collected by GC:", n) print("Uncollectable garbage:", gc.garbage) print("Number of unreachable objects collected by GC:", gc.collect())

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Garbage collector(GC) reference cycle

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PythonObjectGraphs https://mg.pov.lt/objgraph/

import objgraph x = "hello" y = [x, [x], list(x), dict(x=x)]

  • bjgraph.show_refs([y],

filename='sample-graph.png')

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Bestpracticesformemorymanagement

  • Usinggc.collect()carefully

print("Collecting...") n = gc.collect() print("Number of unreachable objects collected:", n) print("Uncollectable garbage:", gc.garbage)

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Garbage collector(GC) methods

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  • Usingwithcontextmanagerforworking

withfiles with open('data.txt', 'r') as file: data = ','.join(line.strip() for line in file)

Bestpracticesformemorymanagement

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  • AvoidListSlicingwith[:]

list= [1,2,3,4] list[1:3] list[slice(1,3)]

Bestpracticesformemorymanagement

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Bestpracticesformemorymanagment

  • StringConcatenation

string= “hello” string+= “world” wordList = ("hello", "world") string = " ".join(wordList)

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  • UseIteratorsandGenerators

Bestpracticesformemorymanagement

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  • https://stackabuse.com/basics-of-memory-management-in-p

ython/

  • https://realpython.com/python-memory-management
  • https://rushter.com/blog/python-garbage-collector
  • https://pythonchb.github.io/PythonTopics/weak_references.

html

References

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https://www.youtube.com/c/JoseManuelOrtegadev