Bug 46774

Summary:	Extreme memory usage in XSSF workbook
Product:	POI	Reporter:	Rob W <rob>
Component:	XSSF	Assignee:	POI Developers List <dev>
Status:	RESOLVED WONTFIX
Severity:	normal
Priority:	P2
Version:	3.5-dev
Target Milestone:	---
Hardware:	All
OS:	All
Attachments:	Sample code that illustrates the bug

Description Rob W 2009-02-26 14:48:15 UTC

Using HSSF, a simple test of 10000 rows by 255 columns runs fine with "-Xms128m -Xmx394m" and is fast.

Using XSSF, the same exact test fails before even getting to 1000 rows, and is extremely slow. After bumping the memory to "-Xms512m -Xmx2048m", it fails somewhere between 3000 and 4000 rows.

Please see the attached sample code, which is based on your Timesheet Demo.

Thank you,
Rob

Comment 1 Rob W 2009-02-26 14:50:35 UTC

This may not be a Macintosh-only problem.  I am hoping to test on another platform shortly.

Comment 2 Rob W 2009-02-26 15:04:13 UTC

Just tested with the same result under Windows Vista, so this does not appear to be a platform-specific issue.

Comment 3 Rob W 2009-02-26 15:08:56 UTC

Created attachment 23317 [details]
Sample code that illustrates the bug

I am resubmitting my original attachment (unchanged), as it isn't appearing in the bug.  If there is a delay and I've submitted it twice, I apologize.

Comment 4 Nick Burch 2009-02-27 04:45:54 UTC

XSSF is xml based, so processing the files will always take more memory than using HSSF. Also, in the interests of developer time, we use XML Beans, which allows faster development at the expense of more memory used.

If this is proving to be a problem for you, do please do some profiling to identify the heavy memory use areas, and contribute back patches to reduce the memory use!

Comment 5 Yegor Kozlov 2009-02-27 06:29:32 UTC

There was a discussion about it some time ago. See http://markmail.org/thread/vqut6wy3ashguz6x

A possible workaround is to stream your data directly in XML.  See an example demonstrating my idea: 
http://svn.apache.org/repos/asf/poi/trunk/src/examples/src/org/apache/poi/xssf/usermodel/examples/BigGridDemo.java

Yegor