https://issues.apache.org/bugzilla/show_bug.cgi?id=52086
--- Comment #2 from Yegor Kozlov <ye...@dinom.ru> 2012-01-14 13:18:28 UTC ---
Finally I had time to review this patch, thanks for your patience.
I made a small change to initialize the useFasterWrite from a system property:
private static final boolean useFasterWrite =
Boolean.getBoolean("org.apache.poi.sstFastWrite");
this way I can test both modes without re-compiling the code.
The patch does improve performance but not that much as in your tests. In the
best case I got 25% faster which is far from "2~4x performance improvement"
observed by you.
In my tests I ran TestSSTRecord#testSSTRecordPerformance() three times in two
sets, either with org.apache.poi.sstFastWrite=true or
org.apache.poi.sstFastWrite=false.
Below is the console output:
-Dorg.apache.poi.sstFastWrite=true
serializer Memory time 0.328 +- 0.003 secs
serializer Memory time 0.302 +- 0.004 secs
serializer Memory time 0.319 +- 0.001 secs
-Dorg.apache.poi.sstFastWrite=false
serializer Memory time 0.381 +- 0.002 secs
serializer Memory time 0.364 +- 0.004 secs
serializer Memory time 0.379 +- 0.001 secs
My test environment:
java: oracle jdk 1.6.0_29 64 bit
option: -Xmx1224m -server
cpu: Intel core i5-2400
OS: windows 7 64bit, 8GB RAM
size of SST: 1<<20
serializer function: Memory
If the performance gain is only 25% then I would stay with current code and not
made such big changes.
Also, can you provide some high-level tests that show how performance improves
when saving real .xls files. How much does SST serialization take from the
total time spent in workbook.write() ?
Regards,
Yegor
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