[FILEUPLOAD-94] Fileupload fails for forms with a large number of inputs

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.0 Final

Environment

Operating System: Linux
Platform: PC

• Bugzilla Id: 24306
• Assignee: Unassigned
• Reporter: Mike Samuel
• Created: 01/Nov/03 04:59
• Updated: 09/Mar/07 20:32
• Resolved: 09/Mar/07 20:32

Description

Attached is a test case servlet which repeats the problem with the Jun 24, 2003
fileupload-1.0 release.

FileUploadBase.parseRequest runs out of memory when parsing a form with a large
number of inputs. The cause seems to be DeferredFileOutputStream which
allocates a ByteArrayOutputStream per input, each of which preallocates a buffer
of length inMemoryThreshold. The in memory threshold defaults to 10k, but if it
is made larger (> 1 M in our environment), then the vm quickly runs out of
memory. Most of this memory is wasted since most files are ~5k, and almost all
non-file inputs are less than 1k.

I patched DeferredFileOutputStream to use a different underlying in memory
stream. I don't really know why ByteArrayOutputStream uses a single byte[],
since you can't do random access on the underlying buffer anyway.
I think the patch is something that could be incorporated into the default file
upload implementation without any noticable change in performance.