> -----Original Message-----
> From: Juozas Baliuka [mailto:[EMAIL PROTECTED]]
> Sent: Thursday, January 17, 2002 8:17 AM
> To: Jakarta Commons Developers List
> Subject: RE: [simplestore] enhancements (was: [simplestore] inital check
> in)
>
>
> >Maybe I understand you wrong, but look at this:
> >In the Cocoon project we have 2 stores a) MRUMemoryStore for quick access
> >and b) JispFilesystemStore for -well- swapping. Why? Because we
> store/cache
> >generated data (xml -> xslt -> html or fop or ...) in the cache.
> Generating
> >this data is very expensive.
>
>
>
> Ok, but it is not memory management, it is optimization for generation.
It is reference management.
> Storing cache to disk has this
> disadvantage :
> if(memory.isLow()){
> // if method "isLow()" correct your cache is in disk, OS did this.
> // else if method "isLow()" is incorrect next has no meaning.
> store.flushToDisk();
>
> }
> void flushToDisk(){
>
> save(memory);// if method "isLow()" was correct you loaded cache from
> disk to memory here , OS did this.
>
> }
> You must find alternative way to Optimize generation, not memory
> management.
>
> I use this way to optimize generation :
>
> Generate content directly to stable storage if don't have it on memory and
> in disk:
>
> SomeStream getContent(Something id){
>
> Content c = find(id);
> if( c != null )return c.openStream();
>
> Content c = generateToStorageFirst(id);
> //cache to memory if possible, if your generation is very expensive and
> your going to copy it to Socket at last,
> // generating content to disk seems very fast :)
>
> return c.openStream();
>
> }
>
> //Optimization is in find
>
> Content find( Something id){
>
> Content c = findInMemoryCache(id);
>
> if (c != null )return c.openStream();
>
> return findInSomeStorage();
>
>
> }
>
> Content generateToStorageFirst(Something id){
>
> Content c = generate(id);
> if(!c.isVeryLage()){
> cache(c);
> }
> return c;
> }
> // constant for the same content;
> bolean isVeryLarge(){
>
> // if very lage, it can be faster to generate, large memory block
> allocation is very expensive.
>
> return lenght > ( totalVirtulMemorySizeForJVMis4GBon32bitOS/
> ConstantCanBeTested ) *
> CanBeTestedAppDependantConstant;
>
>
> }
>
> It is very possible to design it better , but this must be more clear read
> here.
> You never need method "isLow()" it has no meaning, because it is
> impossible
> to implement.
> if application says "low" it does not mean it is true for JVM, if JVM
> says "low" it does not mean it is true for OS.
> if OS never says this for JAVA application. If you have two applications
> on
> your machine "isLow" for OS has no
> meaning in your application, It will not help for OS to move Virtual
> Memory, or application and OS will do it both.
>
>
>
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>
>
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