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From Jonathan Ellis <jbel...@gmail.com>
Subject Re: Testing row cache feature in trunk: write should put record in cache
Date Thu, 18 Feb 2010 20:03:55 GMT
Did you force a GC from jconsole to make sure you weren't just
measuring uncollected garbage?

On Wed, Feb 17, 2010 at 2:51 PM, Weijun Li <weijunli@gmail.com> wrote:
> OK I'll work on the change later because there's another problem to solve:
> the overhead for cache is too big that 1.4mil records (1k each) consumed all
> of the 6gb memory of JVM (I guess 4gb are consumed by the row cache). I'm
> thinking that ConcurrentHashMap is not a good choice for LRU and the row
> cache needs to store compressed key data to reduce memory usage. I'll do
> more investigation on this and let you know.
>
> -Weijun
>
> On Tue, Feb 16, 2010 at 9:22 PM, Jonathan Ellis <jbellis@gmail.com> wrote:
>>
>> ... tell you what, if you write the option-processing part in
>> DatabaseDescriptor I will do the actual cache part. :)
>>
>> On Tue, Feb 16, 2010 at 11:07 PM, Jonathan Ellis <jbellis@gmail.com>
>> wrote:
>> > https://issues.apache.org/jira/secure/CreateIssue!default.jspa, but
>> > this is pretty low priority for me.
>> >
>> > On Tue, Feb 16, 2010 at 8:37 PM, Weijun Li <weijunli@gmail.com> wrote:
>> >> Just tried to make quick change to enable it but it didn't work out :-(
>> >>
>> >>                ColumnFamily cachedRow =
>> >> cfs.getRawCachedRow(mutation.key());
>> >>
>> >>                 // What I modified
>> >>                 if( cachedRow == null ) {
>> >>                     cfs.cacheRow(mutation.key());
>> >>                     cachedRow = cfs.getRawCachedRow(mutation.key());
>> >>                 }
>> >>
>> >>                 if (cachedRow != null)
>> >>                     cachedRow.addAll(columnFamily);
>> >>
>> >> How can I open a ticket for you to make the change (enable row cache
>> >> write
>> >> through with an option)?
>> >>
>> >> Thanks,
>> >> -Weijun
>> >>
>> >> On Tue, Feb 16, 2010 at 5:20 PM, Jonathan Ellis <jbellis@gmail.com>
>> >> wrote:
>> >>>
>> >>> On Tue, Feb 16, 2010 at 7:17 PM, Jonathan Ellis <jbellis@gmail.com>
>> >>> wrote:
>> >>> > On Tue, Feb 16, 2010 at 7:11 PM, Weijun Li <weijunli@gmail.com>
>> >>> > wrote:
>> >>> >> Just started to play with the row cache feature in trunk: it
seems
>> >>> >> to
>> >>> >> be
>> >>> >> working fine so far except that for RowsCached parameter you
need
>> >>> >> to
>> >>> >> specify
>> >>> >> number of rows rather than a percentage (e.g., "20%" doesn't
work).
>> >>> >
>> >>> > 20% works, but it's 20% of the rows at server startup.  So on
a
>> >>> > fresh
>> >>> > start that is zero.
>> >>> >
>> >>> > Maybe we should just get rid of the % feature...
>> >>>
>> >>> (Actually, it shouldn't be hard to update this on flush, if you want
>> >>> to open a ticket.)
>> >>
>> >>
>> >
>
>

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