[Glass] Explanation to "too many failed pom_gen scavenges" in this context??

[Dale Henrichs via Glass]

On 03/08/2016 09:50 AM, Mariano Martinez Peck wrote:
> Hi guys,
>
> First of all, thanks to Richard for the suggestion. Adding the env var 
> did write the useful info in the gem log.
>
> Problem is that even if I tried to fix it (in my code), I still failed 
> :(    I attach the whole log in case someone wants to take a look.
>
> However, I think there is something strange in 
> #installAlmostOutOfMemoryStaticHandler:. I added some logging to this 
> method to see what was going on (in bold the important parts):
>
>
> /installAlmostOutOfMemoryStaticHandler: initialCommitThreshold/
> /  | handler commitThreshold used |/
> /  commitThreshold := initialCommitThreshold./
> /  handler := AlmostOutOfMemory/
> /    addDefaultHandler: [ :ex | /
> /      "Exception caught, do a commit."/
> /      Transcript/
> /        show: 'exception handled: ' , ex printString;/
> /        cr./
> /      System commitTransaction/
> /        ifFalse: [ /
> /          Transcript/
> /            show: 'AutoCommit failed';/
> /            cr./
> /          nil error: 'AutoCommit failed' ]./
> /      System _vmMarkSweep./
> /*Transcript*/
> */        show: 'commit threshold value: ' , commitThreshold 
> printString;/*
> */        cr./*
> */      used := System _tempObjSpacePercentUsedLastMark./*
> */      Transcript/*
> */        show: 'percent used ' , used printString;/*
> */        cr./*
> */      used < commitThreshold/*
> /        ifTrue: [ /
> /          "We dropped below the threshold, reenable the signal"/
> /*Transcript*/
> */            show: 're-enable the signal ';/*
> */            cr./*
> /          System enableAlmostOutOfMemoryError ]/
> /        ifFalse: [ /
> /          "commit and mark sweep did drop us below threshold. cut 
> threshold in half /
> /           and try again. Record an entry in the object log "/
> /          commitThreshold := (100 - commitThreshold) // 2 + 
> commitThreshold./
> /          Transcript/
> /            show: 'commit threshold value: ' , commitThreshold 
> printString;/
> /            cr./
> /          commitThreshold < 98/
> /            ifTrue: [ /
> /              Transcript/
> /                show: 'signalAlmostOutOfMemoryThreshold: ';/
> /                cr./
> /              System signalAlmostOutOfMemoryThreshold: commitThreshold ]/
> /            ifFalse: [ /
> /              "we're with 10% of out of memory, commit instance 
> counts structure /
> /               into objectlog for posterity."/
> /              Transcript/
> /                show: '10% out of memory... record in the object log ';/
> /                cr./
> /              (ObjectLogEntry/
> /                trace: 'almost out of memory: ' , commitThreshold 
> printString/
> /                object: (System _vmInstanceCountsReport: 3)) addToLog./
> /              System commitTransaction/
> /                ifFalse: [ /
> /                  Transcript/
> /                    show: 'Last AutoCommit failed ';/
> /                    cr./
> /                  nil error: 'AutoCommit failed' ] ] ]./
> /      ex resume ]./
> /  SessionTemps current/
> /    at: #'CommitOnAlmostOutOfMemoryStaticException'/
> /    put: handler./
> /  System signalAlmostOutOfMemoryThreshold: commitThreshold/
>
>
>
> Now...if I check the gem log, I get this:
>
> /--transcript--'exception handled: a AlmostOutOfMemory occurred 
> (notification 6013), Session''s temporary object memory is almost full'/
> /--transcript--'commit threshold value: 10'/
> /--transcript--'percent used 0'/
> /--transcript--'re-enable the signal '/
>
> And that 4 lines repeated several times, until it starts with the:
>
>
> /*********** Fatal error 4067 OutOfMemory *****/
> /
> /
> /Printing Smalltalk stack because of OutOfMemory:/
> /Smalltalk stack: printing to topaz .out file at [03/08/2016 
> 12:36:11.827 EST]/
>
>
>
> And this is what I don't understand...from the transcript, it seems 
> that "*/System _tempObjSpacePercentUsedLastMark"/ *always answered 0, 
> hence we are below threshold (no problem!). But then I get the 
> OutOfMemory anyway...  so... how can I run out of memory if 
> #_tempObjSpacePercentUsedLastMark answered 0 each time?
>

Okay the `--transcript--'re-enable the signal '` simply means that the 
AlmostOfMemory signal was re-enabled - the handler is armed - it does 
not guarantee that you won't run out of memory.

The `*********** Fatal error 4067 OutOfMemory *****` means that you ran 
out of memory without triggering an AlmostOutOfMemory exception ... for 
the reasons I mentioned earlier: most likely you ran out of memory 
during a primitive call BEFORE the deferred exception could be signaled ..

BTW, I tried looking at the selector in my 3.2.9 and didn't see symbols, 
so I don't know what methods are actually being called  in the first 
couple of frames, so I can't guess about what might be consuming memory ...

Dale
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