Thanks. So let's see what is the best choice and tell us.
On Oct 11, 2010, at 11:47 AM, Igor Stasenko wrote: > On 11 October 2010 12:10, Stéphane Ducasse <[email protected]> wrote: >> I integrate >> Issue 3086: MCMethodDefinition>>shutdown hack to avoid lock down. >> http://code.google.com/p/pharo/issues/detail?id=3086 >> >> >> >> Igor can you have a look and let me know: >> 1- if we should rollback Issue 3086: MCMethodDefinition>>shutdown >> hack to avoid lock down. >> 2- if we should integrate >> Issue 3048: MC method cache fix >> http://code.google.com/p/pharo/issues/detail?id=3048 >> >> I will integrate >> http://code.google.com/p/pharo/issues/detail?id=3091 >> > > Wait , MCMethodDefinition is only a consequence (however, removing it > from weakdependents would be good idea as well ;)). Yes I integrate it to avoid system hanging. > The real cultprit is HostSystemMenusProxy , which locks the weak > registry during finalization. > Then MCMethodDefinition>>shutdown simply locks at same point (trying > to obtain semaphore lock). > Note, that HostSystemMenusProxy locks finalization process, but not > the process which doing shutdown, > and then during image startup, a new finalization process get created. > That's why removing access to weakdependents in > MCMethodDefinition>>shutdown , kinda solved the issue. > In reality its not. > An old weak registry were sending #finalize outside a critical section: > > finalizeValues > "Some of our elements may have gone away. Look for those and activate > the associated executors." > | finiObjects | > finiObjects := nil. > "First collect the objects." > self protected:[ > valueDictionary allAssociationsDo:[:assoc| > assoc key isNil ifTrue:[ > finiObjects isNil > ifTrue:[finiObjects := > OrderedCollection with: assoc value] > ifFalse:[finiObjects add: assoc value]] > ]. > finiObjects isNil ifFalse:[valueDictionary finalizeValues: > finiObjects asArray]. > ]. > "Then do the finalization" > finiObjects isNil ifTrue:[^self]. > finiObjects do:[:each| each finalize]. > > > So, there two ways to solve it: > a) perform finalization outside a critical section (see attached) > b) fix the HostSystemMenusProxy to prevent any manupulation with weak > registry during finalization. > > > I checked Squeak 4.2 image, and i can also say, that any attempt to > manipulate weak registry during finalization will also lock down a > finalization process (see Squeak's WeakRegistry>>finalizeValues & > WeakKeyDictionary>>finalizeValues) > > So, if we going to assume, in future that it is error to modify weak > registry during finalization, then we should leave the code in > WeakRegistry as-is, and fix HostSystemMenusProxy instead. > If not, the we should make sure that #finalize should be sent outside > weak registry's critical section. > > And the last note: if VM supports new finalization, it will happen > outside a critical section (See the > bottom of WeakRegistry>>finalizeValues). So any manipulations with > registry during finalization can't cause lockdown. > > > P.S. forwarded to Squeak-dev, to make Squeakers aware of potential > danger , when manipulating weak registry during finalization. > > -- > Best regards, > Igor Stasenko AKA sig. > <WeakRegistry-finalizeValues.st>_______________________________________________ > Pharo-project mailing list > [email protected] > http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project _______________________________________________ Pharo-project mailing list [email protected] http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project
