[jboss-user] [JBoss Microcontainer Development] - VFS3 and symlinks

[Marko Strukelj]

Marko Strukelj [http://community.jboss.org/people/mstruk] replied to the discussion

"VFS3 and symlinks"

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I don't think we have any performance tests in VFS yet. I'm also not aware of any JBoss projects performance testing  how-to.

So here are a few things you want to have in mind specifically for testing symlink impact on performance.
 
First, you'll need to create a lot of symlinks, it's best they point to different files (to avoid filesystem caches) - so maybe create one directory with randomly named files and one directory with corresponding symlinks. Put a filename as content of each file.
 
Then use VFS on directory containing symlinks and visitor to iterate over them, read each virtual file - check that the content matches the name. 
 
To compare the result, test nonsymlink access - delete the temp dirs and recreate just the files again using random names. Use VFS on directory containing files.
 
So ... the important thing is to try and neutralize the effect of filesystem caches, although in real life situations there will be a filesystem cache so does it really make sense to avoid it while testing? It depends on what you want to measure really.
 
The question is how realistic scenario the described test would be - having tons of symlinks. It's actually quite unrealistic as you typically don't go create symlinks for individual files, but for whole directories, so a test where the symlinks directory is actually a symlink to files directory is more realistic, but in this case again you benefit from filesystem caches.
 
I'd say - just cover all the scenarios  :) 

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