On Apr 12, 2010, at 5:10 PM, Joe Baldwin wrote:
I have tried to ask this question previously but did not see a
response.
Sorry, prolly missed your previous message.
Assume default cache configuration, will the following call:
((org
.apache
.cayenne
.access
.DataContext
)BaseContext
.getThreadObjectContext()).getObjectStore().getDataRowCache().size()
return the number of DataObjects in DataContext cache for a webapp
(using standard configuration)?
No. getObjectStore().getDataRowCache() returns a shared cache object
used by *all* DataContexts in the system (this assumes the default
"on" value of "use shared cache" checkbox for the DataDomain is not
changed). Also it stores "data rows", i.e. "snapshots" of objects, not
the objects themselves.
(The reason I am asking is that this number this method reports
always grows during the life of the app, even on my dev server. I
would have expected this value to get smaller once all of the
sessions release references to the Select Query array lists, are
nulled, and then GC'd.)
Actually it is an LRU, so once it reaches a certain max size, it stays
constant. The default is 10000 snapshots and can be changed via a
somewhat misnamed "Size of Object Cache" field for the DataDomain in
the Modeler. Just don't set it to a value lower than an expected
concurrent number of uncommitted objects across all contexts in the
system.
What should this number look like during the course of a well
written webapp? Shouldn't the number go up and down depending on
GC? (If there is a better method for visibility, please let me know.)
Since it is an LRU, it should grow to the cache size limit, and then
stay constant.
Andrus
