performance updates to jar and zip

Xueming Shen xueming.shen at
Thu Oct 27 16:37:45 UTC 2011

On 10/27/2011 06:07 AM, Alan Bateman wrote:
> On 27/10/2011 00:19, Xueming Shen wrote:
>> :
>> Here are the "surprising" results.
>>  "nio" is the walkFileTree,
>>  "io" is the File.list()
>>  "io2" is the File.listFiles().
>> The nio's File.walkFileTree is 15 times faster than the "traditional" 
>> recursion+File.list().
>> wow!
> At least for your testing on Linux then if you run with strace then it 
> should become clear. The ioIter and ioIter2 methods in the test result 
> in each file being stat'ed 3 times whereas with walkFileTree it is 
> using Files.readAttributes to attributes in bulk (so one stat per file).
> In any case, this is all good work. One suggestion is to consider not 
> introducing a -T<n> or whatever option but instead default to using a 
> pipeline that has the right number of threads to work very fast in 
> most cases. I'm just thinking of jar tasks in ANT or shell scripts 
> where you wouldn't want to hard code a thread count.

-T is simply here to help measure the performance under different thread 
number. Agreed
that this thing should work by default.


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