[jboss-dev] Further profling: Where should I focus?

[Bill Burke]

David M. Lloyd wrote:
> Caching behavior depends on the filesystem.  For zip mounts, "isDirectory" 
> and "lastModified" don't even hit the filesystem (in most cases).  Don't 
> take JProfiler data as real-world timing; it's useful to find slow spots, 
> sometimes, but it's not an accurate reflection of what the real speed of 
> the thing is.
> 
> For real filesystem stuff, you CAN NOT EVER do any form of caching of file 
> metainformation because the backing data is not owned by VFS, and thus can 
> change without any sort of notice.
> 

You can and should cache everything and anything because the App Server 
doesn't need live VFS-based information because 90% of the time it is 
static with the other 10% happening on redeployment.

As I stated early, define a parallel non-cache api that invalidates the 
cache on diffs for sensitive operations (like hot-deployment).

> Try the test again with a "warmed up" JVM and no profiler agent installed 
> and you'll probably see a different story.
> 

No different story here.  JVM "warm up" has no effect.  Still the VFS 
taking 60% of the time.

-- 
Bill Burke
JBoss, a division of Red Hat
http://bill.burkecentral.com