[jira] [Commented] (NET-493) FTPClient: Slow data transfer rate if __bufferSize != 0

["Erik Wramner (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/NET-493?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13545699#comment-13545699 ] 

Erik Wramner commented on NET-493:
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I don't know if this is the root cause, but we have had severe performance issues with FTP using commons-net 3.2. A file that normally takes seconds to transfer may take more than an hour. We have observed that often the file is transferred relatively quickly, but then it can take a very long time before the response from the remote server that the file has been successfully received reaches our code (and the logs in commons-net). Reverting to 3.1 solves the performance issues. We are using JDK 1.7_09 on Windows Server 2003.
                
> FTPClient: Slow data transfer rate if __bufferSize != 0
> -------------------------------------------------------
>
>                 Key: NET-493
>                 URL: https://issues.apache.org/jira/browse/NET-493
>             Project: Commons Net
>          Issue Type: Bug
>          Components: FTP
>    Affects Versions: 3.2
>         Environment: Windows 7 32bit / Windows XP 32bit
>            Reporter: Mico Micic
>              Labels: ftpclient
>         Attachments: screenshot-1.jpg, screenshot-2.jpg
>
>
> The patch applied in [NET-465|https://issues.apache.org/jira/browse/NET-465] causes a very slow data transfer rate. The line {code}850: socket.setSendBufferSize(__bufferSize){code} in {code}_openDataConnection_{code} sets the buffer size to 1024  by default. With this size I had a very bad transfer rate on windows 7 and XP. The wireshark log shows that each FTP-DATA packet is exactly 1024 bytes long and has to be acknowledged on the TCP layer before the next one is sent. I don't know why, but when I set the buffer size to 0 (FTPClient.setBufferSize) the transfer rate is fine. 

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