https://issues.apache.org/bugzilla/show_bug.cgi?id=54593
Bug ID: 54593
Summary: Poor performance when adding borders
Product: POI
Version: 3.9
Hardware: PC
Status: NEW
Severity: normal
Priority: P2
Component: XSSF
Assignee: [email protected]
Reporter: [email protected]
Classification: Unclassified
Created attachment 29974
--> https://issues.apache.org/bugzilla/attachment.cgi?id=29974&action=edit
generated XSSF workbooks with and witout bordering
Hi,
i just started with Apache POI and created a simple test XSSF workbook (see
attached files, sheet is locked, password is "kuku"). I noticed a big gap in
elapsed times after adding borders. Small benchmark (average of 10 consecutive
runs) on my i5@2,5GHz notebook (Oracle JDK 1.7, JVM setting -Xmx256M) shows
XSSF no borders: 700ms
XSSF borders: 2500ms
HSSF borders: 290ms
I use RegionUtil for bordering (as is suggested in the quick guide) and my
bordering helper method looks like
private static void thinBorder(Workbook wb, Sheet sh, CellRangeAddress rng) {
RegionUtil.setBorderBottom(CellStyle.BORDER_THIN, rng, sh, wb);
RegionUtil.setBorderLeft(CellStyle.BORDER_THIN, rng, sh, wb);
RegionUtil.setBorderRight(CellStyle.BORDER_THIN, rng, sh, wb);
RegionUtil.setBorderTop(CellStyle.BORDER_THIN, rng, sh, wb);
}
and i use that approach for bordering single cells as well. After a small
debugging, i found that underlaying calls to CellUtil method
private static void setFormatProperties(CellStyle style, Workbook workbook,
Map<String, Object> properties)
take 30-70ms each. Combined with a creation of different styles during the
bordering, that might be the cause of my problem. Without borders, there are 9
different styles (based on Workbook.getNumCellStyles()), with borders, there
are 66 styles.
Perhaps my bordering strategy can be optimised, but creation of approx. 25
styles per second (if i understand the code logic well) seems like poor
performance and could be a stopper for big workbooks with formatting. I
understand that the HSSF implementation migh be more effective avoiding XML,
but the difference simply seems too big.
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