Hi, I made ftp client program using WinINet API.
The client first connects to the FTP server and downloads all of files in current directory.

The flow is like this.
------------------
InternetOpen(...)
InternetConnect(...)
FtpFindFirstFile(...)
(loop)
FtpGetFile(..)
InternetFindNextFile(..)
InternetCloseHandle(hFindFirstFile);
InternetCloseHandle(hConnect);
InternetCloseHandle(hOpen);
------------------

The situation is,
there are 100 FTP servers and I want run my own ftp client which inside running 5 threads each implements above routine.

As a result, some thread fail to get files.
My question is that FTP sessions(each connects another ftp server) couldn't run simultaneously

This is likely to be a concurrency problem. How have you implemented your application Do you have a pool of jobs waiting to be completed (like the 100 servers waiting to be listed), then e.g. 5 threads fetching new pending work items from that pool If so, do you have any kind of interlocking, so two jobs won't be taken on by more than one thread, if they all happen to "look" for new jobs at the same time

Are there any other aspects of your application that you could share with us