Long delays before chunk uploads begin

[webrunner]

Hi there,

we're uploading very large files (> 4GB) which basically works good using the on-the-fly-chunking. Unfortunelaty, we're experiencing long delays before each chunk when the upload process has been running for a while. For example, currently I have a 4 GB-file that has been transferred by about 80%, and the applet says that it's uploading chunk 384 of 410, but the progress is frozen. After about 2-3 minutes(!), it starts the upload process of the chunk (10 MB chunks), and at the next chunks, it's the same.
Is there any possibility to optimize this behaviour? The delays take much more time than the upload itself at large files.

[support]

There could be a small delay to go to file offset but 2-3 minutes seems a lot. We're going to ry to reproduce this issue. Do you have an AntiVirus enabled ?

[webrunner]

No, there's no antivirus. I tested on a Mac, Firefox and Safari, but on Windows it's the same, but I don't know if there is an antivirus on Windows.

[support]

I guess the time to split is short at beginning and then it becomes longer as much the chunk id increase, correct ? I'm going to make a test.

[webrunner]

Yes, that's exactly how it is.

[support]

What is the chunk size ? 1MB or 10MB ?
I've just made a test (3GB file) under Windows XP (both applet and script on the same machine) with a 10MB chunksize and it works perfectly. There is no delay. The problem might be on server-side when the chunks are appended to final file.
Does the applet take long time to start chunk upload or to return on each when it's at 100% ?

[webrunner]

What is the chunk size ? 1MB or 10MB ?

The chunk size is 10 MB.

I've just made a test (3GB file) under Windows XP (both applet and script on the same machine) with a 10MB chunksize and it works perfectly. There is no delay. The problem might be on server-side when the chunks are appended to final file.
Does the applet take long time to start chunk upload or to return on each when it's at 100% ?

I add a logfile entry on the server side when the chunk has been appended, and after that, the applet displays "Upload complete" for the chunk, which indicates (I suppose) that the applet received a 200 status. After that, the delay appears, so to answer your question, it seems to appear on the beginning of a chunk.