Odd result with canonical paths with intermixed usage of java.io.File and java.nio.file.Files APIs

Alan Bateman Alan.Bateman at oracle.com
Mon Dec 11 14:25:36 UTC 2017

On 11/12/2017 14:06, Jaikiran Pai wrote:
> :
> So a few related questions that I have are:
>     1. Is this inconsistency an expected behaviour or is this a bug?
>     2. If this is an expected behaviour, then would it be a better 
> idea (as an application developer) to use Path.toRealPath[2] instead 
> of using the File.getCanonicalPath()? Are these 2 APIs semantically 
> equivalent? The File.getCanonicalPath() talks about the canonical path 
> being "unique" paths but the Path.toRealPath has no such mentions.
The correctness issues with the canonicalization cache is a long 
standing issue [1]. You can workaround it by running with 
-Dsun.io.useCanonCaches=false as I think you have found. The goal is to 
eventually disable and remove it. The first steps to get there happened 
in JDK 9 when FilePermission was changed to not canonicalize by default 
(FilePermission was the original motivation for this cache).

If you have follow-up questions then please bring the thread to 


[1] https://bugs.openjdk.java.net/browse/JDK-7066948

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