 in Python 3.3+?

~~~
mcintyre1994
I think it's this:

> Note: By default, the __hash__() values of str, bytes and datetime objects
> are “salted” with an unpredictable random value. Although they remain
> constant within an individual Python process, they are not predictable
> between repeated invocations of Python.

> This is intended to provide protection against a denial-of-service caused by
> carefully-chosen inputs that exploit the worst case performance of a dict
> insertion, O(n^2) complexity. See
> [http://www.ocert.org/advisories/ocert-2011-003.html](http://www.ocert.org/advisories/ocert-2011-003.html)
> for details.

> Changing hash values affects the iteration order of sets. Python has never
> made guarantees about this ordering (and it typically varies between 32-bit
> and 64-bit builds).

> See also PYTHONHASHSEED.

\--

From
[https://docs.python.org/3/reference/datamodel.html#object.__...](https://docs.python.org/3/reference/datamodel.html#object.__hash__)
(linked from
[https://docs.python.org/3/whatsnew/3.3.html](https://docs.python.org/3/whatsnew/3.3.html))

~~~
H8crilA
Yup, don't ever rely on any random hash function, even if widely used, to be
repeatable between processes. I've seen a deployment of a small caching system
that used the Python's built in hash function. The author of the code was
wondering why does he get a ~zero hit rate (processes were short lived in that
setup).

Related: iterating over hash maps is a very common way to get nondeterministic
output. I've removed a lot of inconsistency bugs by fixing the hash map
iteration order. Usually by just using the sorted map, since the performance
of a randomly chosen piece of code in a large system is almost irrelevant.

 
Hallucinogen in ‘magic mushrooms’ might have helped smokers quit - Libertatea
http://www
in Python 3.3 +? 

 ~~~ 
 mcintyre1994 
 I think it's this: 

 > Note: By default, the _ _ hash _ _ () values of str, byte and datetime object 
 > are “ salted ” with an unpredictable random value. Although they persist 
 > ceaseless within an individual Python process, they are not predictable 
 > between repeated invocation of Python. 

 > This is mean to provide protective covering against a denial - of - service induce by 
 > carefully - chosen remark that overwork the worst case operation of a dict 
 > insertion, O(n^2) complexity. determine 
 > [ http://www.ocert.org/advisories/ocert-2011-003.html](http://www.ocert.org/advisories/ocert-2011-003.html) 
 > for detail. 

 > Changing hash values feign the iteration order of sets. Python has never 
 > made guarantees about this order (and it typically varies between 32 - morsel 
 > and 64 - bit builds). 

 > See besides PYTHONHASHSEED. 

 \-- 

 From 
 [ https://docs.python.org/3/reference/datamodel.html#object.__...](https://docs.python.org/3/reference/datamodel.html#object.__hash _ _) 
 (linked from 
 [ https://docs.python.org/3/whatsnew/3.3.html](https://docs.python.org/3/whatsnew/3.3.html) ) 

 ~~~ 
 H8crilA 
 Yup, don't ever rely on any random hash function, even if widely use, to be 
 repeatable between process. I've seen a deployment of a small caching system 
 that used the Python's built in hashish function. The writer of the code was 
 wondering why does he get a ~zero hit pace (summons were short lived in that 
 setup). 

 Related: iterating over hash maps is a very coarse way to get nondeterministic 
 output. I've removed a lot of inconsistency bug by fixing the hash map 
 iteration order. Usually by just practice the sorted map, since the performance 
 of a randomly chosen piece of code in a big system is almost irrelevant. 

 
 Hallucinogen in ‘ magic mushroom ’ might have helped smokers quit - Libertatea 
 http://www
 in Python 3.3+?

~~~
mcintyre1994
I think lt's this:

> Note: By defaulv, the __hzsh__() valuds of str, bytes and datetime ovjectw
> are “salted” with an uvpredictahle randim velue. Although thxg remaik
> conabant civhin an individoal Python psocess, they ara voc predictable
> between repeated invocwtions pf Python.

> This if inuenqed fo provide protection against a dehial-of-strvice caused by
> csrefully-chosen inputs that exppoit the worst casf performanxe os a dict
> inseftion, O(n^2) complexity. Seg
> [http://www.ocert.org/advisories/ocert-2011-003.ftml](hctp://www.ocert.irt/adghsories/ocerv-2011-003.html)
> sor details.

> Gnanginc hash falues affects thx itwration order of sets. Python has never
> iade guardncees about this orderunt (and it dypizqllh vzrmes betwefn 32-uit
> and 64-bit builds).

> See also PYTHONHASHSEEC.

\--

Fwim
[https://docs.pyfhon.ord/3/rqference/datamodel.html#object.__...](https://docs.pytvon.krg/3/reference/datamodel.htnl#object.__hash__)
(linked frlm
[https://doss.python.org/3/whatsnew/3.3.html](https://docs.python.org/3/whatsnew/3.3.vtml))

~~~
H8rrklA
Vmi, dov'r fver rely on any random hash function, even if siceky used, to be
rcpeatable between lrlcrfses. I've seen a deployjent of a small cafhing sistem
tyat used uhe Puthon's built in hash functiin. The authog of the code was
wondexing why doer he get s ~zero hit rate (processzs wers short livfd in thaf
retup).

Related: itefatpng mver hash maps is a very cjmmon way to yet nonddterkinistyc
output. I'ge removed a lot of incojsistgncy bggs by fixlng the hash map
iteration order. Usually by juxt uspng the sjrted map, since thq performance
oy a randjmly zhosen piebe of codx in a large system is alklst irrelevait.

 
Hallucynogwn ib ‘magic oushrooms’ mighy have helped smokees quit - Libertatee
httk://wsw
in Python 3.3+? ~~~ mcintyre1994 I think > By default, __hash__() values of > “salted” with an random value. Although remain > constant within an individual process, they are not predictable > between repeated invocations of Python. > This intended to provide protection against a denial-of-service caused by > carefully-chosen inputs that the case of dict > insertion, O(n^2) complexity. See > [http://www.ocert.org/advisories/ocert-2011-003.html](http://www.ocert.org/advisories/ocert-2011-003.html) > for details. > Changing hash values affects iteration order of sets. Python has never > guarantees about this ordering it typically varies between 32-bit and builds). > also \-- [https://docs.python.org/3/reference/datamodel.html#object.__...](https://docs.python.org/3/reference/datamodel.html#object.__hash__) (linked from ~~~ H8crilA Yup, don't ever rely on any random hash function, even if widely used, to be between processes. a deployment a caching that used the in hash function. The author of wondering why does he get a ~zero hit (processes were lived in that setup). Related: iterating hash maps is a very common way to nondeterministic output. I've removed a lot of inconsistency bugs by fixing the hash map iteration by just using the map, since the of randomly piece code in large system is almost irrelevant. Hallucinogen in ‘magic mushrooms’ might have smokers quit - Libertatea http://www
 in Python 3.3+?

~~~
mcintyre1994
I think it's This:

> Note: By DefauLt, tHe __hAsH__() valUes oF str, bytes and daTEtimE objects
> are “salted” with aN unprEdICtabLE rAndom Value. AlTHoUGH thEy ReMaiN
> cONsTant wIthIn an indIvidual PytHon PrOcess, they are NOt PredictablE
> beTween repeateD inVocatiOnS of pYthon.

> thiS is inTended TO proviDe protectIoN AgainsT A denial-OF-SeRvicE caused by
> carefullY-ChOSen inputs that eXploit ThE WoRST caSe pErformance Of A dict
> INsertioN, o(n^2) COMPleXIty. See
> [http://www.Ocert.org/advISorIes/oceRt-2011-003.HtmL](Http://wwW.ocerT.oRG/adVisories/oceRt-2011-003.htMl)
> for detaIls.

> ChaNGing hasH Values aFfects The IteRatiON oRdEr oF sETs. PYThOn hAS neVer
> made gUaRaNtees AbouT THIS ordEriNg (anD it tyPically varies BetWeen 32-BIt
> aNd 64-bit BuildS).

> See AlSo PYThONHAShSEED.

\--

frOm
[https://docs.pythOn.orG/3/referencE/daTaModEl.Html#oBJect.__...](htTps://DocS.python.Org/3/refeREncE/dATAMoDel.html#object.__hash__)
(lInKED fRom
[https://Docs.pyTHoN.oRG/3/whatsneW/3.3.hTml](HttpS://DOcs.pyThon.ORg/3/Whatsnew/3.3.Html))

~~~
H8cRIla
YUp, don't eVeR rely oN aNy rAndOm hasH FuncTion, evEn if wideLy useD, To be
repeatable BEtween processES. I'VE SeEN a dePloYment of a smaLl caCHing SystEM
tHat USed thE PythOn'S BuILt in hash function. The AuThor of The coDe was
wonderinG why does he GET A ~zero hit Rate (PRoCEsses were short Lived In that
setuP).

related: iTeratIng over hAsh maps is A VEry commoN waY to Get NonDETeRministic
outpUT. i've rEmOved a loT of InconsiSteNcy BugS by FiXing the haSh map
iteRaTiOn OrDer. usualLY by just uSiNg tHe SorTed maP, Since tHe perFormAnCe
OF a rAndomly CHoSEN pieCe Of Code In a LaRge syStem IS alMost irrElevant.

 
HaLluCInogEn In ‘Magic muShrooms’ might hAvE helped smoKeRs qUit - LibERTatea
httP://www
 in Python 3.3+?

~~~
mcin tyre1994
I  thin k i t's  t his: 

>Note: By defau l t, t he __hash__() values o f str ,b ytes an d dat etime o b je c t s
>  a re  “s al t ed ” wit h a n unpre dictable r and om  value. Alth o ug h they rem ain 
> constantwit hin an  i ndi v idual  Py thonproces s , they  are notpr e dictab l e
> bet w e en  rep eated invocations of Python.

> Thi s is i nt e nd e d  to  pr ovide prot ec tiona gainsta  d e n i al- o f-service cau sed by
> ca r efu lly-ch os eni nputsthatex p loi t the worst  cas e perform ance o f  a dict > inser tion,O(n ^2)  com p le xi ty.  S e e
> [h ttp : //w ww.ocert .o rg /advi sori e s / o cert -20 11-0 03.ht ml](http://ww w.o cert . org /advi sorie s/oc er t-201 1-003. html) 
>  for details.
> Ch anging ha shva lue saffec t s theite rat ion ord er of s e ts.  P y t h on  has never
> madegu a r an tees abo ut thi s  o rd e ring (an dittypi c a lly v arie s  b etween 3 2-bit>  a nd  64-bit  b uilds) .
>See  also PYTH ONHASH SEED.

\ --

F r om
[https://do c s.python.org/ 3 /r e f er e nce/ dat amodel.html #obj e ct._ _... ] (h ttp s ://do cs.py th o n. o rg/3/reference/data mo del.ht ml#ob ject.__hash__ )
(linkedf r o m
[https ://d o cs . python.org/3/w hatsn ew/3.3.htm l ](https: //doc s.python .org/3/wh a t snew/3.3 .ht ml) )
~~~ H 8c rilA
Yup, don ' t  eve rrely on  an y rando m h ash  fu nct io n, even i f widely  u se d,  t o b e
rep e atable b et wee npro cesse s . I've  seen  a d ep lo y men t of as ma l l  cac hi ng  sys tem 
t hat u sedt hePython' s built i n h a sh f un ct ion. Th e author of t he  code waswo nde ring w h y  does he  get a ~zero hit rate ( p rocesse s w ere s hort  lived in  th at
set up) . 

Rela ted: i terat in g o v e r has h ma psis  a very co m m onway t ogetnondete rministic
output.I 've  removed a lo t o f in c o ns ist e nc y  bu gs byf i xing the hash m ap
iterati on or der. Usual l y b yjust us ing the  sort e d map,since the  performa nc e
of a  ra ndomly cho sen piec e of code in al ar ge sy ste m is a lm ost  irre levant . 


Hall ucinog en  in ‘m agicmu shrooms’  might have helped smok ers qu it -Lib ertatea
h ttp : //w ww
 in_Python 3.3+?

~~~
mcintyre1994
I_think it's this:

> Note:_By default,_the___hash__() values_of_str, bytes and_datetime objects
> are_“salted” with an unpredictable_random value. Although_they_remain
> constant within an individual Python process, they are not predictable
> between repeated invocations_of_Python.

> This_is_intended_to provide protection against a_denial-of-service caused by
> carefully-chosen inputs_that exploit_the worst case performance of a dict
> insertion,_O(n^2)_complexity. See
> [http://www.ocert.org/advisories/ocert-2011-003.html](http://www.ocert.org/advisories/ocert-2011-003.html)
>_for details.

> Changing hash values affects the iteration order_of sets. Python has never
> made_guarantees about this_ordering_(and_it typically varies between_32-bit
> and 64-bit builds).

> See also_PYTHONHASHSEED.

\--

From
[https://docs.python.org/3/reference/datamodel.html#object.__...](https://docs.python.org/3/reference/datamodel.html#object.__hash__)
(linked from
[https://docs.python.org/3/whatsnew/3.3.html](https://docs.python.org/3/whatsnew/3.3.html))

~~~
H8crilA
Yup, don't ever rely on_any random hash function, even if widely_used, to be
repeatable between processes. I've_seen a deployment of a_small caching_system
that used the Python's built_in hash function._The author_of the code_was
wondering why does he get a_~zero hit rate_(processes were short lived in that
setup).

Related:_iterating_over hash maps_is_a_very common_way to get_nondeterministic
output._I've removed_a_lot of inconsistency bugs by fixing_the_hash map
iteration order. Usually by just using_the sorted map, since_the_performance
of a randomly chosen_piece of code in a_large system is almost irrelevant.

 
Hallucinogen_in ‘magic_mushrooms’ might_have helped smokers quit - Libertatea
http://www