Can I get a notification before fullGC?

Georg Gollmann gollmann at
Thu Oct 12 08:13:18 UTC 2006

Am 12.10.2006 um 04:18 schrieb Bert Freudenberg:
> Am 12.10.2006 um 03:59 schrieb Yoshiki Ohshima:
>>   Is there any way to get some sort of notification right *before* a
>> fullGC happens so that some guys release their cache?
> Not that I know of.
>> ... releases the cache only when a big memory clean up is
>> required.
> You could add it to the memoryHogs list ...
> - Bert -

Yes, that is exactly the scenario I had in mind way back then (2000):
> The current LowSpaceWatcher just alerts the user. This is not  
> useful for servers or for situations when objects are cached and  
> should be discarded when space becomes tight. I have now  
> generalized the mechanism used in my MailArchiver (http:// 
> As an example setup is now:
>   Smalltalk memoryHogs add: ArchivedMail
> When space is low #freeSomeSpace gets sent:
>   ArchivedMail>freeSomeSpace
>    "Remove all cached text from my instances."
>    self allInstancesDo: [ :m | m purgeText ]
> If freeSomeSpace fails to free enough memory - maybe because no  
> memoryHogs have been registered - the old behavior (alert the user)  
> is invoked.

I don´t know, if the stuff still works in the current Squeak version,  

Kind regards

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