From: Ellen K. 

That was actually a very informative post, I am saving it.  Thank you.

On Fri, 20 May 2005 11:10:59 +0100, Adam
 wrote in message
:

>Ellen K. wrote:
>
>> It was an analogy.  If you want your database to do a transaction you
>> have to BEGIN TRANSACTION before it starts doing stuff and COMMIT
>> TRANSACTION when it's done.  ROLLBACK TRANSACTION goes in your error
>> handlers that come after each piece, so that if one piece fails, all the
>> pieces that came before get rolled back.
>>
>> And GC means garbage collection, one problem with which is that you
>> never know when the garbage collector is going to do its thing.
>>
>
>That's not true. You can call System.gc() whenever you wish or indeed
>when it makes sense. Garbage collecting per se has a huge range of
>possible solutions which is partly dependant upon ram etc e.g:
>
>low ram - many & often.  Possibly called by app at the end of a given
>process (e.g. I show you something graphical & I know it wll take you a
>little time to read & make a decision ergo paint & .gc())
>
>high ram - few & far between. Possibly called by the program at a time
>which makes sense (e.g. if load is low). i.e. if the time taken to gc &
>thus the service slowdown is more important than ram useage then...wait
>till it's quiet & do gc then....
>
>In embedded/low power/mem systems then gc becomes important not just to
>free up memory but actually because memory consumes energy & if you want
>a long battery life then you will need to minimise your use of memory
>where possible.
>
>What is more you can set some aspects of gc at the commandline/start
>time e.g. java (since 1.4 at least) takes the following args:
>
>-Xnoclassgc       disable class garbage collection
>-Xincgc           enable incremental garbage collection
>-Xloggc:    log GC status to a file with time stamps
>
>& then you have the inital mem settings e.g.:
>
>    -Xms        set initial Java heap size
>    -Xmx        set maximum Java heap size
>    -Xss        set java thread stack size
>
>& then you can watch what's going on so as to set your wn .gc() calls via
>
>-XX:+PrintGCDetails
>
>
>& then finally you have:
>
>-XX:+DisableExplicitGC
>
>Where upon your program is entirely responsible for doing the gc via .gc().
>
>
>Adam

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