FilePermission Canonical path optimization

[Sean Mullan]

Hi,

Can you elaborate more on the performance degradation that you are 
seeing at startup? Are you seeing this when you are running with or 
without a SecurityManager? If without a SecurityManager, can you provide 
some code paths/examples? As far as I can see, with the proposed fix you 
are moving the performance hit to runtime, and it will be triggered the 
first time a FilePermission check is made, and at worst case it may need 
to canonicalize all the FilePermissions in the FilePermissionCollection. 
Also, with the latest proposed fix you are potentially making 
performance worse by introducing synchronized blocks (which as Peter 
noted, still have some race conditions). I can understand why you want 
to improve application startup, but I want to make sure I understand the 
use case(s) a little better first.

Thanks,
Sean

On 12/01/2014 03:06 AM, deven you wrote:
> Hi All,
>   File.getCanonicalPath() is a very time-consuming method, we observed
> significant performance degradation from some application's startup stage
> with java.io.FilePermission. However, lazying load the calls to
> getCanonicalPath() from java.ioFilePermission is straightforward and solve
> this problem effectively. Openjdk bug[1]  tracks this bug and here is the
> patch [2]. Could anyone take a look?
>
> [1] https://bugs.openjdk.java.net/browse/JDK-8066211
> [2] http://cr.openjdk.java.net/~youdwei/ojdk-912/webrev.00/
>