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From bugzi...@apache.org
Subject [Bug 53508] Performance XSSFCell.setCellValue(String) is very slow
Date Thu, 05 Jul 2012 11:24:37 GMT
https://issues.apache.org/bugzilla/show_bug.cgi?id=53508

--- Comment #2 from velten@econda.de ---
Hello Yegor

Thank you for very fast response!

I must admit, that I tried to create a testcase, but failed. 

But problem on our server persisted.

I recognized that the problem disappeared only with server restart. First I
recognized this on our testing server. Then I proofed this a second time at our
production server.

I was able to measure the difference: Long running server performance was
around 30 times slower than fresh started server. 

After some over night XMLX-Exports on our production server the performance is
down again (perhaps 20 times slower). Test server has had no workload and is
unchanged fast.


We figured out only with thread dumps, that the SharedStringsTable Hash Key
Generation is perhaps the problem, because threads was hanging in this method
very often.

Obviously the POI code causes not the 30 times slowdown in performance. Perhaps
there is a bad cache implementation or something else in the XML-Beans code?

Currently I have not tested your code snippet. Surely this could help to speed
up POI anyway.

I will try to search something further..   


Before Server restart:
2012-07-04 16:44:42,423 ERROR table.Table.serializeXLS() (729) - serializeXLS
for 31681 rows with 20 columns for user 'XXX' lasted 473392 with an avg of
14.942457624443673 per row

After Server restart:
2012-07-04 18:56:29,686 ERROR table.Table.serializeXLS() (729) - serializeXLS
for 31681 rows with 20 columns for user 'XXX' lasted 14919 with an avg of
0.4709131656197721 per row

After some over night export workload this morning:
2012-07-05 10:52:00,446 ERROR table.Table.serializeXLS() (729) - serializeXLS
for 31680 rows with 20 columns for user 'XXX' lasted 281254 with an avg of
8.877967171717172 per row

(Each of this durations was stable reproducible over several test export runs)

Best wishes

Daniel

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