High frequency statistical sampling profiler¶

A new statistical sampling profiler has been added to the newprofiling module asprofiling.sampling. This profiler enables low-overhead performance analysis ofrunning Python processes without requiring code modification or process restart.

Unlike deterministic profilers (cProfile andprofile) that instrumentevery function call, the sampling profiler periodically captures stack traces fromrunning processes. This approach provides virtually zero overhead while achievingsampling rates ofup to 1,000,000 Hz, making it the fastest sampling profileravailable for Python (at the time of its contribution) and ideal for debuggingperformance issues in production environments.

Key features include:

• Zero-overhead profiling: Attach to any running Python process withoutaffecting its performance

• No code modification required: Profile existing applications without restart

• Real-time statistics: Monitor sampling quality during data collection

• Multiple output formats: Generate both detailed statistics and flamegraph data

• Thread-aware profiling: Option to profile all threads or just the main thread

Profile process 1234 for 10 seconds with default settings:

python-mprofiling.sampling1234

Profile with custom interval and duration, save to file:

python-mprofiling.sampling-i50-d30-oprofile.stats1234

Generate collapsed stacks for flamegraph:

python-mprofiling.sampling--collapsed1234

Profile all threads and sort by total time:

python-mprofiling.sampling-a--sort-tottime1234

The profiler generates statistical estimates of where time is spent:

Real-timesamplingstats:Mean:100261.5Hz(9.97µs)Min:86333.4Hz(11.58µs)Max:118807.2Hz(8.42µs)Samples:400001Captured498841samplesin5.00secondsSamplerate:99768.04samples/secErrorrate:0.72%ProfileStats:nsamplessample%tottime(s)cumul%cumtime(s)filename:lineno(function)43/4188580.00.00087.94.189case.py:667(TestCase.run)3293/4188120.70.03387.94.188case.py:613(TestCase._callTestMethod)158562/15856233.31.58633.31.586test_compile.py:725(TestSpecifics.test_compiler_recursion_limit.<locals>.check_limit)129553/12955327.21.29627.21.296ast.py:46(parse)0/1281290.00.00026.91.281test_ast.py:884(AST_Tests.test_ast_recursion_limit.<locals>.check_limit)7/674460.00.00014.20.674test_compile.py:729(TestSpecifics.test_compiler_recursion_limit)6/603800.00.00012.70.604test_ast.py:888(AST_Tests.test_ast_recursion_limit)3/500200.00.00010.50.500test_compile.py:727(TestSpecifics.test_compiler_recursion_limit)1/380110.00.0008.00.380test_ast.py:886(AST_Tests.test_ast_recursion_limit)1/250760.00.0005.30.251test_compile.py:728(TestSpecifics.test_compiler_recursion_limit)22361/223624.70.2244.70.224test_compile.py:1368(TestSpecifics.test_big_dict_literal)4/180080.00.0003.80.180test_ast.py:889(AST_Tests.test_ast_recursion_limit)11/176960.00.0003.70.177subprocess.py:1038(Popen.__init__)16968/169683.60.1703.60.170subprocess.py:1900(Popen._execute_child)2/169410.00.0003.60.169test_compile.py:730(TestSpecifics.test_compiler_recursion_limit)Legend:nsamples:Direct/Cumulativesamples(directexecuting/oncallstack)sample%:Percentageoftotalsamplesthisfunctionwasdirectlyexecutingtottime:Estimatedtotaltimespentdirectlyinthisfunctioncumul%:Percentageoftotalsampleswhenthisfunctionwasonthecallstackcumtime:Estimatedcumulativetime(includingtimeincalledfunctions)filename:lineno(function):FunctionlocationandnameSummaryofInterestingFunctions:FunctionswithHighestDirect/CumulativeRatio(HotSpots):1.000direct/cumulativeratio,33.3%directsamples:test_compile.py:(TestSpecifics.test_compiler_recursion_limit.<locals>.check_limit)1.000direct/cumulativeratio,27.2%directsamples:ast.py:(parse)1.000direct/cumulativeratio,3.6%directsamples:subprocess.py:(Popen._execute_child)FunctionswithHighestCallFrequency(IndirectCalls):418815indirectcalls,87.9%totalstackpresence:case.py:(TestCase.run)415519indirectcalls,87.9%totalstackpresence:case.py:(TestCase._callTestMethod)159470indirectcalls,33.5%totalstackpresence:test_compile.py:(TestSpecifics.test_compiler_recursion_limit)FunctionswithHighestCallMagnification(Cumulative/Direct):12267.9xcallmagnification,159470indirectcallsfrom13direct:test_compile.py:(TestSpecifics.test_compiler_recursion_limit)10581.7xcallmagnification,116388indirectcallsfrom11direct:test_ast.py:(AST_Tests.test_ast_recursion_limit)9740.9xcallmagnification,418815indirectcallsfrom43direct:case.py:(TestCase.run)

The profiler automatically identifies performance bottlenecks through statisticalanalysis, highlighting functions with high CPU usage and call frequency patterns.

This capability is particularly valuable for debugging performance issues inproduction systems where traditional profiling approaches would be too intrusive.

(Contributed by Pablo Galindo and László Kiss Kollár ingh-135953.)

Improved error messages¶

• The interpreter now provides more helpful suggestions inAttributeErrorexceptions when accessing an attribute on an object that does not exist, buta similar attribute is available through one of its members.

  For example, if the object has an attribute that itself exposes the requestedname, the error message will suggest accessing it via that inner attribute:

  @dataclassclassCircle:radius:float@propertydefarea(self)->float:returnpi*self.radius**2classContainer:def__init__(self,inner:Circle)->None:self.inner=innercircle=Circle(radius=4.0)container=Container(circle)print(container.area)

  Running this code now produces a clearer suggestion:

  Traceback (most recent call last):File "/home/pablogsal/github/python/main/lel.py", line 42, in <module>   print(container.area)         ^^^^^^^^^^^^^^AttributeError:'Container' object has no attribute 'area'. Did you mean: 'inner.area'?

collections¶

• Addedcollections.Counter.__xor__() andcollections.Counter.__ixor__() to compute the symmetric differencebetweenCounter objects.(Contributed by Raymond Hettinger ingh-138682.)

collections.abc¶

• collections.abc.ByteString has been removed fromcollections.abc.__all__.collections.abc.ByteString has beendeprecated since Python 3.12, and is scheduled for removal in Python 3.17.

• The following statements now causeDeprecationWarnings to be emitted atruntime:

  • fromcollections.abcimportByteString

  • importcollections.abc;collections.abc.ByteString.

  DeprecationWarnings were already emitted ifcollections.abc.ByteString was subclassed or used as the secondargument toisinstance() orissubclass(), but warnings were notpreviously emitted if it was merely imported or accessed from thecollections.abc module.

dbm¶

• Added newreorganize() methods todbm.dumb anddbm.sqlite3which allow to recover unused free space previously occupied by deleted entries.(Contributed by Andrea Oliveri ingh-134004.)

difflib¶

• Introduced the optionalcolor parameter todifflib.unified_diff(),enabling color output similar togit diff.This can be controlled byenvironment variables.(Contributed by Douglas Thor ingh-133725.)

• Improved the styling of HTML diff pages generated by thedifflib.HtmlDiffclass, and migrated the output to the HTML5 standard.(Contributed by Jiahao Li ingh-134580.)

hashlib¶

• Ensure that hash functions guaranteed to be alwaysavailable exist asattributes ofhashlib even if they will not work at runtime due tomissing backend implementations. For instance,hashlib.md5 will nolonger raiseAttributeError if OpenSSL is not available and Pythonhas been built without MD5 support.(Contributed by Bénédikt Tran ingh-136929.)

http.client¶

• A newmax_response_headers keyword-only parameter has been added toHTTPConnection andHTTPSConnectionconstructors. This parameter overrides the default maximum number of allowedresponse headers.(Contributed by Alexander Enrique Urieles Nieto ingh-131724.)

http.cookies¶

• Allow ‘"’ double quotes in cookie values.(Contributed by Nick Burns and Senthil Kumaran ingh-92936.)

locale¶

• setlocale() now supports language codes with@-modifiers.@-modifier are no longer silently removed ingetlocale(),but included in the language code.(Contributed by Serhiy Storchaka ingh-137729.)

math¶

• Addmath.isnormal() andmath.issubnormal() functions.(Contributed by Sergey B Kirpichev ingh-132908.)

• Addmath.fmax(),math.fmin() andmath.signbit() functions.(Contributed by Bénédikt Tran ingh-135853.)

mmap¶

• mmap.mmap now has atrackfd parameter on Windows;if it isFalse, the file handle corresponding tofileno willnot be duplicated.(Contributed by Serhiy Storchaka ingh-78502.)

os.path¶

• Add support of the all-but-last mode inrealpath().(Contributed by Serhiy Storchaka ingh-71189.)

• Thestrict parameter toos.path.realpath() accepts a new value,os.path.ALLOW_MISSING.If used, errors other thanFileNotFoundError will be re-raised;the resulting path can be missing but it will be free of symlinks.(Contributed by Petr Viktorin forCVE 2025-4517.)

resource¶

• Add new constants:RLIMIT_NTHR,RLIMIT_UMTXP,RLIMIT_THREADS,RLIM_SAVED_CUR, andRLIM_SAVED_MAX.(Contributed by Serhiy Storchaka ingh-137512.)

shelve¶

• Added newreorganize() method toshelve used to recover unused freespace previously occupied by deleted entries.(Contributed by Andrea Oliveri ingh-134004.)

socket¶

• Add constants for the ISO-TP CAN protocol.(Contributed by Patrick Menschel and Stefan Tatschner ingh-86819.)

sqlite3¶

• Thecommand-line interface has several new features:

  • SQL keyword completion on <tab>.(Contributed by Long Tan ingh-133393.)

  • Prompts, error messages, and help text are now colored.This is enabled by default, seeControlling color fordetails.(Contributed by Stan Ulbrych and Łukasz Langa ingh-133461.)

ssl¶

• Indicate throughssl.HAS_PSK_TLS13 whether thessl modulesupports “External PSKs” in TLSv1.3, as described in RFC 9258.(Contributed by Will Childs-Klein ingh-133624.)

• Added new methods for managing groups used for SSL key agreement

  • ssl.SSLContext.set_groups() sets the groups allowed for doingkey agreement, extending the previousssl.SSLContext.set_ecdh_curve() method.This new API provides the ability to list multiple groups andsupports fixed-field and post-quantum groups in addition to ECDHcurves. This method can also be used to control what key sharesare sent in the TLS handshake.

  • ssl.SSLSocket.group() returns the group selected for doing keyagreement on the current connection after the TLS handshake completes.This call requires OpenSSL 3.2 or later.

  • ssl.SSLContext.get_groups() returns a list of all available keyagreement groups compatible with the minimum and maximum TLS versionscurrently set in the context. This call requires OpenSSL 3.5 or later.

  (Contributed by Ron Frederick ingh-136306.)

• Added a new methodssl.SSLContext.set_ciphersuites() for setting TLS 1.3ciphers. For TLS 1.2 or earlier,ssl.SSLContext.set_ciphers() shouldcontinue to be used. Both calls can be made on the same context and theselected cipher suite will depend on the TLS version negotiated when aconnection is made.(Contributed by Ron Frederick ingh-137197.)

• Added new methods for managing signature algorithms:

  • ssl.get_sigalgs() returns a list of all available TLS signaturealgorithms. This call requires OpenSSL 3.4 or later.

  • ssl.SSLContext.set_client_sigalgs() sets the signature algorithmsallowed for certificate-based client authentication.

  • ssl.SSLContext.set_server_sigalgs() sets the signature algorithmsallowed for the server to complete the TLS handshake.

  • ssl.SSLSocket.client_sigalg() returns the signature algorithmselected for client authentication on the current connection. This callrequires OpenSSL 3.5 or later.

  • ssl.SSLSocket.server_sigalg() returns the signature algorithmselected for the server to complete the TLS handshake on the currentconnection. This call requires OpenSSL 3.5 or later.

  (Contributed by Ron Frederick ingh-138252.)

sys¶

• Addsys.abi_info namespace to improve access to ABI information.(Contributed by Klaus Zimmermann ingh-137476.)

tarfile¶

• data_filter() now normalizes symbolic link targets in order toavoid path traversal attacks.(Contributed by Petr Viktorin ingh-127987 andCVE 2025-4138.)

• extractall() now skips fixing up directory attributeswhen a directory was removed or replaced by another kind of file.(Contributed by Petr Viktorin ingh-127987 andCVE 2024-12718.)

• extract() andextractall()now (re-)apply the extraction filter when substituting a link (hard orsymbolic) with a copy of another archive member, and when fixing updirectory attributes.The former raises a new exception,LinkFallbackError.(Contributed by Petr Viktorin forCVE 2025-4330 andCVE 2024-12718.)

• extract() andextractall()no longer extract rejected members whenerrorlevel() is zero.(Contributed by Matt Prodani and Petr Viktorin ingh-112887andCVE 2025-4435.)

• extract() andextractall()now replace slashes by backslashes in symlink targets on Windows to preventcreation of corrupted links.(Contributed by Christoph Walcher ingh-57911.)

timeit¶

• The command-line interface now colorizes error tracebacksby default. This can be controlled withenvironment variables.(Contributed by Yi Hong ingh-139374.)

types¶

• Expose the write-throughlocals() proxy typeastypes.FrameLocalsProxyType.This represents the type of theframe.f_locals attribute,as described inPEP 667.

unittest¶

• unittest.TestCase.assertLogs() will now accept a formatterto control how messages are formatted.(Contributed by Garry Cairns ingh-134567.)

xml.parsers.expat¶

• AddSetAllocTrackerActivationThreshold()andSetAllocTrackerMaximumAmplification()toxmlparser objects to tune protections againstdisproportional amounts of dynamic memory usage from within an Expat parser.(Contributed by Bénédikt Tran ingh-90949.)

• AddSetBillionLaughsAttackProtectionActivationThreshold()andSetBillionLaughsAttackProtectionMaximumAmplification()toxmlparser objects to tune protections againstbillion laughs attacks.(Contributed by Bénédikt Tran ingh-90949.)

zlib¶

• Allow combining two Adler-32 checksums viaadler32_combine().(Contributed by Callum Attryde and Bénédikt Tran ingh-134635.)

• Allow combining two CRC-32 checksums viacrc32_combine().(Contributed by Bénédikt Tran ingh-134635.)

module_name¶

• TODO

CLI¶

• Deprecate-b and-bb command line optionsand schedule them to become no-op in Python 3.17.These were primarily helpers for the Python 2 -> 3 transition.Starting with Python 3.17, noBytesWarning will be raisedfor these cases; use a type checker instead.

  (Contributed by Nikita Sobolev ingh-136355.)

hashlib¶

• In hash function constructors such asnew() or thedirect hash-named constructors such asmd5() andsha256(), their optional initial data parameter couldalso be passed a keyword argument nameddata= orstring= invarioushashlib implementations.

  Support for thestring keyword argument name is now deprecated andis slated for removal in Python 3.19. Prefer passing the initial data asa positional argument for maximum backwards compatibility.

  (Contributed by Bénédikt Tran ingh-134978.)

__version__¶

• The__version__ attribute has been deprecated in these standard librarymodules and will be removed in Python 3.20.Usesys.version_info instead.

  • argparse

  • csv

  • ctypes.macholib

  • ipaddress

  • json

  • logging (__date__ also deprecated)

  • optparse

  • pickle

  • platform

  • re

  • socketserver

  • tabnanny

  • tkinter.font

  • tkinter.ttk

  (Contributed by Hugo van Kemenade ingh-76007.)

Pending removal in Python 3.16¶

• The import system:

  • Setting__loader__ on a module whilefailing to set__spec__.loaderis deprecated. In Python 3.16,__loader__ will cease to be set ortaken into consideration by the import system or the standard library.

• array:

  • The'u' format code (wchar_t)has been deprecated in documentation since Python 3.3and at runtime since Python 3.13.Use the'w' format code (Py_UCS4)for Unicode characters instead.

• asyncio:

  • asyncio.iscoroutinefunction() is deprecatedand will be removed in Python 3.16;useinspect.iscoroutinefunction() instead.(Contributed by Jiahao Li and Kumar Aditya ingh-122875.)

  • asyncio policy system is deprecated and will be removed in Python 3.16.In particular, the following classes and functions are deprecated:

    • asyncio.AbstractEventLoopPolicy

    • asyncio.DefaultEventLoopPolicy

    • asyncio.WindowsSelectorEventLoopPolicy

    • asyncio.WindowsProactorEventLoopPolicy

    • asyncio.get_event_loop_policy()

    • asyncio.set_event_loop_policy()

    Users should useasyncio.run() orasyncio.Runner withloop_factory to use the desired event loop implementation.

    For example, to useasyncio.SelectorEventLoop on Windows:

    importasyncioasyncdefmain():...asyncio.run(main(),loop_factory=asyncio.SelectorEventLoop)

    (Contributed by Kumar Aditya ingh-127949.)

• builtins:

  • Bitwise inversion on boolean types,~True or~Falsehas been deprecated since Python 3.12,as it produces surprising and unintuitive results (-2 and-1).Usenotx instead for the logical negation of a Boolean.In the rare case that you need the bitwise inversion ofthe underlying integer, convert toint explicitly (~int(x)).

• functools:

  • Calling the Python implementation offunctools.reduce() withfunctionorsequence as keyword arguments has been deprecated since Python 3.14.

• logging:

  Support for custom logging handlers with thestrm argument is deprecatedand scheduled for removal in Python 3.16. Define handlers with thestreamargument instead. (Contributed by Mariusz Felisiak ingh-115032.)

• mimetypes:

  • Valid extensions start with a ‘.’ or are empty formimetypes.MimeTypes.add_type().Undotted extensions are deprecated and willraise aValueError in Python 3.16.(Contributed by Hugo van Kemenade ingh-75223.)

• shutil:

  • TheExecError exceptionhas been deprecated since Python 3.14.It has not been used by any function inshutil since Python 3.4,and is now an alias ofRuntimeError.

• symtable:

  • TheClass.get_methods methodhas been deprecated since Python 3.14.

• sys:

  • The_enablelegacywindowsfsencoding() functionhas been deprecated since Python 3.13.Use thePYTHONLEGACYWINDOWSFSENCODING environment variable instead.

• sysconfig:

  • Thesysconfig.expand_makefile_vars() functionhas been deprecated since Python 3.14.Use thevars argument ofsysconfig.get_paths() instead.

• tarfile:

  • The undocumented and unusedTarFile.tarfile attributehas been deprecated since Python 3.13.

Pending removal in Python 3.17¶

• collections.abc:

  • collections.abc.ByteString is scheduled for removal in Python 3.17.

    Useisinstance(obj,collections.abc.Buffer) to test ifobjimplements thebuffer protocol at runtime. For usein type annotations, either useBuffer or a unionthat explicitly specifies the types your code supports (e.g.,bytes|bytearray|memoryview).

    ByteString was originally intended to be an abstract class thatwould serve as a supertype of bothbytes andbytearray.However, since the ABC never had any methods, knowing that an object was aninstance ofByteString never actually told you anything usefulabout the object. Other common buffer types such asmemoryviewwere also never understood as subtypes ofByteString (either atruntime or by static type checkers).

    SeePEP 688 for more details.(Contributed by Shantanu Jain ingh-91896.)

• typing:

  • Before Python 3.14, old-style unions were implemented using the private classtyping._UnionGenericAlias. This class is no longer needed for the implementation,but it has been retained for backward compatibility, with removal scheduled for Python3.17. Users should use documented introspection helpers liketyping.get_origin()andtyping.get_args() instead of relying on private implementation details.

  • typing.ByteString, deprecated since Python 3.9, is scheduled for removal inPython 3.17.

    Useisinstance(obj,collections.abc.Buffer) to test ifobjimplements thebuffer protocol at runtime. For usein type annotations, either useBuffer or a unionthat explicitly specifies the types your code supports (e.g.,bytes|bytearray|memoryview).

    ByteString was originally intended to be an abstract class thatwould serve as a supertype of bothbytes andbytearray.However, since the ABC never had any methods, knowing that an object was aninstance ofByteString never actually told you anything usefulabout the object. Other common buffer types such asmemoryviewwere also never understood as subtypes ofByteString (either atruntime or by static type checkers).

    SeePEP 688 for more details.(Contributed by Shantanu Jain ingh-91896.)

Pending removal in Python 3.19¶

• ctypes:

  • Implicitly switching to the MSVC-compatible struct layout by setting_pack_ but not_layout_on non-Windows platforms.

• hashlib:

  • In hash function constructors such asnew() or thedirect hash-named constructors such asmd5() andsha256(), their optional initial data parameter couldalso be passed a keyword argument nameddata= orstring= invarioushashlib implementations.

    Support for thestring keyword argument name is now deprecatedand slated for removal in Python 3.19.

    Before Python 3.13, thestring keyword parameter was not correctlysupported depending on the backend implementation of hash functions.Prefer passing the initial data as a positional argument for maximumbackwards compatibility.

Pending removal in Python 3.20¶

• The__version__ attribute has been deprecated in these standard librarymodules and will be removed in Python 3.20.Usesys.version_info instead.

  • argparse

  • csv

  • ctypes.macholib

  • ipaddress

  • json

  • logging (__date__ also deprecated)

  • optparse

  • pickle

  • platform

  • re

  • socketserver

  • tabnanny

  • tkinter.font

  • tkinter.ttk

  (Contributed by Hugo van Kemenade ingh-76007.)

Pending removal in future versions¶

The following APIs will be removed in the future,although there is currently no date scheduled for their removal.

• argparse:

  • Nesting argument groups and nesting mutually exclusivegroups are deprecated.

  • Passing the undocumented keyword argumentprefix_chars toadd_argument_group() is nowdeprecated.

  • Theargparse.FileType type converter is deprecated.

• builtins:

  • Generators:throw(type,exc,tb) andathrow(type,exc,tb)signature is deprecated: usethrow(exc) andathrow(exc) instead,the single argument signature.

  • Currently Python accepts numeric literals immediately followed by keywords,for example0inx,1orx,0if1else2. It allows confusing andambiguous expressions like[0x1forxiny] (which can be interpreted as[0x1forxiny] or[0x1forxiny]). A syntax warning is raisedif the numeric literal is immediately followed by one of keywordsand,else,for,if,in,is andor. In a future release itwill be changed to a syntax error. (gh-87999)

  • Support for__index__() and__int__() method returning non-int type:these methods will be required to return an instance of a strict subclass ofint.

  • Support for__float__() method returning a strict subclass offloat: these methods will be required to return an instance offloat.

  • Support for__complex__() method returning a strict subclass ofcomplex: these methods will be required to return an instance ofcomplex.

  • Delegation ofint() to__trunc__() method.

  • Passing a complex number as thereal orimag argument in thecomplex() constructor is now deprecated; it should only be passedas a single positional argument.(Contributed by Serhiy Storchaka ingh-109218.)

• calendar:calendar.January andcalendar.February constants aredeprecated and replaced bycalendar.JANUARY andcalendar.FEBRUARY.(Contributed by Prince Roshan ingh-103636.)

• codecs: useopen() instead ofcodecs.open(). (gh-133038)

• codeobject.co_lnotab: use thecodeobject.co_lines() methodinstead.

• datetime:

  • utcnow():usedatetime.datetime.now(tz=datetime.UTC).

  • utcfromtimestamp():usedatetime.datetime.fromtimestamp(timestamp,tz=datetime.UTC).

• gettext: Plural value must be an integer.

• importlib:

  • cache_from_source()debug_override parameter isdeprecated: use theoptimization parameter instead.

• importlib.metadata:

  • EntryPoints tuple interface.

  • ImplicitNone on return values.

• logging: thewarn() method has been deprecatedsince Python 3.3, usewarning() instead.

• mailbox: Use of StringIO input and text mode is deprecated, useBytesIO and binary mode instead.

• os: Callingos.register_at_fork() in multi-threaded process.

• pydoc.ErrorDuringImport: A tuple value forexc_info parameter isdeprecated, use an exception instance.

• re: More strict rules are now applied for numerical group referencesand group names in regular expressions. Only sequence of ASCII digits is nowaccepted as a numerical reference. The group name in bytes patterns andreplacement strings can now only contain ASCII letters and digits andunderscore.(Contributed by Serhiy Storchaka ingh-91760.)

• shutil:rmtree()’sonerror parameter is deprecated inPython 3.12; use theonexc parameter instead.

• ssl options and protocols:

  • ssl.SSLContext without protocol argument is deprecated.

  • ssl.SSLContext:set_npn_protocols() andselected_npn_protocol() are deprecated: use ALPNinstead.

  • ssl.OP_NO_SSL* options

  • ssl.OP_NO_TLS* options

  • ssl.PROTOCOL_SSLv3

  • ssl.PROTOCOL_TLS

  • ssl.PROTOCOL_TLSv1

  • ssl.PROTOCOL_TLSv1_1

  • ssl.PROTOCOL_TLSv1_2

  • ssl.TLSVersion.SSLv3

  • ssl.TLSVersion.TLSv1

  • ssl.TLSVersion.TLSv1_1

• threading methods:

  • threading.Condition.notifyAll(): usenotify_all().

  • threading.Event.isSet(): useis_set().

  • threading.Thread.isDaemon(),threading.Thread.setDaemon():usethreading.Thread.daemon attribute.

  • threading.Thread.getName(),threading.Thread.setName():usethreading.Thread.name attribute.

  • threading.currentThread(): usethreading.current_thread().

  • threading.activeCount(): usethreading.active_count().

• typing.Text (gh-92332).

• The internal classtyping._UnionGenericAlias is no longer used to implementtyping.Union. To preserve compatibility with users using this privateclass, a compatibility shim will be provided until at least Python 3.17. (Contributed byJelle Zijlstra ingh-105499.)

• unittest.IsolatedAsyncioTestCase: it is deprecated to return a valuethat is notNone from a test case.

• urllib.parse deprecated functions:urlparse() instead

  • splitattr()

  • splithost()

  • splitnport()

  • splitpasswd()

  • splitport()

  • splitquery()

  • splittag()

  • splittype()

  • splituser()

  • splitvalue()

  • to_bytes()

• wsgiref:SimpleHandler.stdout.write() should not do partialwrites.

• xml.etree.ElementTree: Testing the truth value of anElement is deprecated. In a future release itwill always returnTrue. Prefer explicitlen(elem) orelemisnotNone tests instead.

• sys._clear_type_cache() is deprecated:usesys._clear_internal_caches() instead.

ctypes¶

• Removed the undocumented functionctypes.SetPointerType(),which has been deprecated since Python 3.13.(Contributed by Bénédikt Tran ingh-133866.)

glob¶

• Removed the undocumentedglob.glob0() andglob.glob1()functions, which have been deprecated since Python 3.13. Useglob.glob() and pass a directory to itsroot_dir argument instead.(Contributed by Barney Gale ingh-137466.)

http.server¶

• Removed theCGIHTTPRequestHandler classand the--cgi flag from thepython -m http.servercommand-line interface. They were deprecated in Python 3.13.(Contributed by Bénédikt Tran ingh-133810.)

importlib.resources¶

• Removed deprecatedpackage parameterfromimportlib.resources.files() function.(Contributed by Semyon Moroz ingh-138044)

pathlib¶

• Removed deprecatedpathlib.PurePath.is_reserved().Useos.path.isreserved() to detect reserved paths on Windows.(Contributed by Nikita Sobolev ingh-133875.)

platform¶

• Removed theplatform.java_ver() function,which was deprecated since Python 3.13.(Contributed by Alexey Makridenko ingh-133604.)

sre_*¶

• Removedsre_compile,sre_constants andsre_parse modules.(Contributed by Stan Ulbrych ingh-135994.)

sysconfig¶

• Removed thecheck_home parameter ofsysconfig.is_python_build().(Contributed by Filipe Laíns ingh-92897.)

threading¶

• Remove support for arbitrary positional or keyword arguments in the Cimplementation ofRLock objects. This was deprecatedin Python 3.14.(Contributed by Bénédikt Tran ingh-134087.)

typing¶

• The undocumented keyword argument syntax for creatingNamedTuple classes (for example,Point=NamedTuple("Point",x=int,y=int)) is no longer supported.Use the class-based syntax or the functional syntax instead.(Contributed by Bénédikt Tran ingh-133817.)

• UsingTD=TypedDict("TD") orTD=TypedDict("TD",None) toconstruct aTypedDict type with zero field is nolonger supported. UseclassTD(TypedDict):passorTD=TypedDict("TD",{}) instead.(Contributed by Bénédikt Tran ingh-133823.)

• Code likeclassExtraTypeVars(P1[S],Protocol[T,T2]):... now raisesaTypeError, becauseS is not listed inProtocol parameters.(Contributed by Nikita Sobolev ingh-137191.)

• Code likeclassB2(A[T2],Protocol[T1,T2]):... now correctly handlestype parameters order: it is(T1,T2), not(T2,T1)as it was incorrectly infered in runtime before.(Contributed by Nikita Sobolev ingh-137191.)

• typing.ByteString has been removed fromtyping.__all__.typing.ByteString has been deprecated since Python 3.9, and isscheduled for removal in Python 3.17.

• The following statements now causeDeprecationWarnings to be emitted atruntime:

  • fromtypingimportByteString

  • importtyping;typing.ByteString.

  DeprecationWarnings were already emitted iftyping.ByteStringwas subclassed or used as the second argument toisinstance() orissubclass(), but warnings were not previously emitted if it was merelyimported or accessed from thetyping module.

unicodedata¶

• The Unicode database has been updated to Unicode 17.0.0.

wave¶

• Removed thegetmark(),setmark() andgetmarkers() methodsof theWave_read andWave_write classes,which were deprecated since Python 3.13.(Contributed by Bénédikt Tran ingh-133873.)

zipimport¶

• Remove deprecatedzipimport.zipimporter.load_module().Usezipimport.zipimporter.exec_module() instead.(Contributed by Jiahao Li ingh-133656.)

New features¶

• AddPySys_GetAttr(),PySys_GetAttrString(),PySys_GetOptionalAttr(), andPySys_GetOptionalAttrString()functions as replacements forPySys_GetObject().(Contributed by Serhiy Storchaka ingh-108512.)

• AddPyUnstable_Unicode_GET_CACHED_HASH to get the cached hash ofa string. See the documentation for caveats.(Contributed by Petr Viktorin ingh-131510.)

• Add API for checking an extension module’s ABI compatibility:Py_mod_abi,PyABIInfo_Check(),PyABIInfo_VARandPy_mod_abi.(Contributed by Petr Viktorin ingh-137210.)

• ImplementPEP 782, thePyBytesWriter API.Add functions:

  • PyBytesWriter_Create()

  • PyBytesWriter_Discard()

  • PyBytesWriter_FinishWithPointer()

  • PyBytesWriter_FinishWithSize()

  • PyBytesWriter_Finish()

  • PyBytesWriter_Format()

  • PyBytesWriter_GetData()

  • PyBytesWriter_GetSize()

  • PyBytesWriter_GrowAndUpdatePointer()

  • PyBytesWriter_Grow()

  • PyBytesWriter_Resize()

  • PyBytesWriter_WriteBytes()

  (Contributed by Victor Stinner ingh-129813.)

• AddPyTuple_FromArray() to create atuple from an array.(Contributed by Victor Stinner ingh-111489.)

Porting to Python 3.15¶

• sqlite3.Connection APIs has been cleaned up.

  • All parameters ofsqlite3.connect() exceptdatabase are now keyword-only.

  • The first three parameters of methodscreate_function()andcreate_aggregate() are now positional-only.

  • The first parameter of methodsset_authorizer(),set_progress_handler() andset_trace_callback() is now positional-only.

  (Contributed by Serhiy Storchaka ingh-133595.)

• Private functions promoted to public C APIs:

  Thepythoncapi-compat project can be used to get most of these newfunctions on Python 3.14 and older.

• resource.RLIM_INFINITY is now always positive.Passing a negative integer value that corresponded to its old value(such as-1 or-3, depending on platform) toresource.setrlimit() andresource.prlimit() is now deprecated.(Contributed by Serhiy Storchaka ingh-137044.)

• resize() has been removed on platforms that don’t support theunderlying syscall, instead of raising aSystemError.

Deprecated C APIs¶

• For unsigned integer formats inPyArg_ParseTuple(),accepting Python integers with value that is larger than the maximal valuefor the C type or less than the minimal value for the correspondingsigned integer type of the same size is now deprecated.(Contributed by Serhiy Storchaka ingh-132629.)

• PyBytes_FromStringAndSize(NULL,len)and_PyBytes_Resize() aresoft deprecated,use thePyBytesWriter API instead.(Contributed by Victor Stinner ingh-129813.)

• Deprecatecval field of the thePyComplexObject type.UsePyComplex_AsCComplex() andPyComplex_FromCComplex()to convert a Python complex number to/from the CPy_complexrepresentation.(Contributed by Sergey B Kirpichev ingh-128813.)

• Functions_Py_c_sum(),_Py_c_diff(),_Py_c_neg(),_Py_c_prod(),_Py_c_quot(),_Py_c_pow() and_Py_c_abs() aresoft deprecated.(Contributed by Sergey B Kirpichev ingh-128813.)

• bytes_warning is deprecatedsince 3.15 and will be removed in 3.17.(Contributed by Nikita Sobolev ingh-136355.)

Removed C APIs¶

• Remove deprecatedPyUnicode functions:

  • PyUnicode_AsDecodedObject():UsePyCodec_Decode() instead.

  • PyUnicode_AsDecodedUnicode():UsePyCodec_Decode() instead; Note that some codecs (for example, “base64”)may return a type other thanstr, such asbytes.

  • PyUnicode_AsEncodedObject():UsePyCodec_Encode() instead.

  • PyUnicode_AsEncodedUnicode():UsePyCodec_Encode() instead; Note that some codecs (for example, “base64”)may return a type other thanbytes, such asstr.

  (Contributed by Stan Ulbrych ingh-133612.)

• PyImport_ImportModuleNoBlock(): deprecated aliasofPyImport_ImportModule().(Contributed by Bénédikt Tran ingh-133644.)

• PyWeakref_GetObject() andPyWeakref_GET_OBJECT:usePyWeakref_GetRef() instead. Thepythoncapi-compat projectcan be used to getPyWeakref_GetRef() on Python 3.12 and older.(Contributed by Bénédikt Tran ingh-133644.)

• Remove deprecatedPySys_ResetWarnOptions().Clearsys.warnoptions andwarnings.filters instead.

  (Contributed by Nikita Sobolev ingh-138886.)

The following functions are removed in favor ofPyConfig_Get().Thepythoncapi-compat project can be used to getPyConfig_Get()on Python 3.13 and older.

• Python initialization functions:

  • Py_GetExecPrefix():usePyConfig_Get("base_exec_prefix")(sys.base_exec_prefix) instead.UsePyConfig_Get("exec_prefix")(sys.exec_prefix) ifvirtual environmentsneed to be handled.

  • Py_GetPath():usePyConfig_Get("module_search_paths")(sys.path) instead.

  • Py_GetPrefix():usePyConfig_Get("base_prefix")(sys.base_prefix) instead.UsePyConfig_Get("prefix")(sys.prefix) ifvirtual environmentsneed to be handled.

  • Py_GetProgramFullPath():usePyConfig_Get("executable")(sys.executable) instead.

  • Py_GetProgramName():usePyConfig_Get("executable")(sys.executable) instead.

  • Py_GetPythonHome():usePyConfig_Get("home") or thePYTHONHOME environment variable instead.

  (Contributed by Bénédikt Tran ingh-133644.)