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

[Jason T. Greene]

Andrew Dinn wrote:
> On 01/05/2010 07:42 PM, Bill Burke wrote:
>> public List<Closeable> recursiveMount(VirtualFile file) throws
>> IOException
>>      {
>>         ArrayList<Closeable>  mounts = new ArrayList<Closeable>();
>>
>>         if (!file.isDirectory()&&
>> file.getName().matches("^.*\\.([EeWwJj][Aa][Rr]|[Zz][Ii][Pp])$"))
>>            mounts.add(VFS.mountZip(file, file, provider));
>>
>>         /****** Doubled speedup when this was commented out!!!!!!!!!!!!
>>         if (file.isDirectory())
>>            for (VirtualFile child : file.getChildren())
>>               mounts.addAll(recursiveMount(child));
>>               */
>>
>>
>>         return mounts;
>>      }
> 
> Irrespective of the answer to any general issues over caching it is 
> clear in this case that the 2 calls to file.isDirectory() can quite 
> legitimately be replaced with a single call and a local variable to 
> stash/test the result (it's a shame the compiler cannot figure this out 
> but so it goes). Since this code actually turned up in the profiling as 
> a major source of overhead then the obvious thing to do in response is 
> patch it and see what turns up next then keep going until easy to fix 
> things like this stop turning up. Saves us wasting time in protracted 
> arguments as well ;-)

In addition you don't want to do regex matching like that. However, code 
like this is not actually going to be in the AS, it was just a quick and 
dirty routine for a test case. So that bit was blown out of proportion.

-- 
Jason T. Greene
JBoss, a division of Red Hat