QFile::exists( filename ) slow

[lni]

Hello, I have about 3,000,000 small files in a directory tree that needs to be ftped through network.

I use QNetworkAccessManager to handle the job. About 1,000,000 files have been ftped to another computers, so I tar those files and untar into the target computer, and I do

foreach(  filename, fileList ) {
 
     if ( !QFile::exists( filename ) ) {
 
        // start ftp filename using QNetworkAccessManager.
 
     }
 
 
   }

foreach(  filename, fileList ) {

     if ( !QFile::exists( filename ) ) {

        // start ftp filename using QNetworkAccessManager.

     }


   }

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However, QFile::exists( filename ) takes a lot of time (about 0.02 second ) per file. If I kills the program and restart it, those files that have been checked by QFile::exists( filename ) will return quickly ( 0.001 seconds ), that is 20 times faster.

How can I solve this problem?

Thanks.