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Posted to dev@poi.apache.org by bu...@apache.org on 2011/03/04 12:04:46 UTC
DO NOT REPLY [Bug 50868] New: Performance of
sheet.setDefaultColumnStyle(col, style) degrades as more columns are added
https://issues.apache.org/bugzilla/show_bug.cgi?id=50868
Summary: Performance of sheet.setDefaultColumnStyle(col, style)
degrades as more columns are added
Product: POI
Version: 3.7
Platform: All
OS/Version: All
Status: NEW
Severity: normal
Priority: P2
Component: XSSF
AssignedTo: dev@poi.apache.org
ReportedBy: ajit_bhagvat@yahoo.com
CC: ajit_bhagvat@yahoo.com
Created an attachment (id=26729)
--> (https://issues.apache.org/bugzilla/attachment.cgi?id=26729)
Java program to test performance of sheet.setDefaultColumnStyle(col, style) for
different no. of columns
When creating an Excel sheet with thousands of columns, the performance of
sheet.setDefaultColumnStyle(col, style) keeps degrading as more and more
columns are added. For every call to this method with a new column, the time
taken by the method keeps on increasing.
Please execute the attached test program with 1000 columns or more, and notice
the time taken by the method for every 100th column. The CPU consumption also
reaches 100% during execution of the program.
Please note: Though the test program sets only one default style for all the
columns, in practice, I need to create an Excel sheet with different default
styles for different columns.
Because of the performance issue, creating large Excel sheets with thousands of
columns is time-consuming and it is also consuming a lot of CPU for the entire
duration.
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DO NOT REPLY [Bug 50868] Performance of
sheet.setDefaultColumnStyle(col, style) degrades as more columns are added
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=50868
ajit_bhagvat@yahoo.com changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEEDINFO |NEW
--- Comment #2 from ajit_bhagvat@yahoo.com 2011-03-09 07:21:35 EST ---
Nick, you are right. I modified my code as per your suggestion and as you
suspected ColumnHelper.getColumn1Based is the source of the slowdown.
Here is the modified for loop:
ColumnHelper helper = sheet.getColumnHelper();
for(int i = 0; i < numCols; i++) {
long startTime = System.currentTimeMillis();
// sheet.setDefaultColumnStyle(i, style);
CTCol col = helper.getColumn1Based(i+1, true);
if ((i+1)%100 == 0) {
long endTime = System.currentTimeMillis();
System.out.printf("Time for setting default column style on %4dth
column (ms): %10d%n", (i+1), (endTime-startTime));
}
if (col == null) {
col = sheet.getCTWorksheet().getColsArray(0).addNewCol();
col.setMin(i+1);
col.setMax(i+1);
}
col.setStyle(style.getIndex());
}
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DO NOT REPLY [Bug 50868] Performance of
sheet.setDefaultColumnStyle(col, style) degrades as more columns are added
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=50868
Nick Burch <ni...@alfresco.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |NEEDINFO
--- Comment #3 from Nick Burch <ni...@alfresco.com> 2011-03-14 17:34:23 EDT ---
I have a feeling that we might need to re-write the search as an xpath, rather
than the current method of iterating to find the correct one
(We probably don't want to try to maintain a cache, as other code could easily
change the CTCol entries)
Can you try seeing how an xpath would perform? You need to get the CTSheet off
the XSSFSheet, then get the CTCols, and finally do a simple xpath query (eg to
get the child with a known attribute). If that looks to perform ok as you add
the columns, then we know it's a good bet for switching too.
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DO NOT REPLY [Bug 50868] Performance of
sheet.setDefaultColumnStyle(col, style) degrades as more columns are added
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=50868
Nick Burch <ni...@alfresco.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |NEEDINFO
--- Comment #1 from Nick Burch <ni...@alfresco.com> 2011-03-04 06:11:17 EST ---
I suspect that ColumnHelper.getColumn1Based is the source of the slowdown -
because a CTCol entry can cover more than one column we currently need to loop
over all of them to find the appropriate spot
Can you try making a call to getColumn1Based for your columns instead of the
set style call, and see if that shows the same problem?
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