LiuGuoMing wrote:
Hi,ALL
java.lang.OutOfMemoryError: Java heap space
I'm currently using POI to generate some fairly large Excel files
(30,000+ rows), using the org.apache.poi.hssf.usermodel package.
it occur 'java.lang.OutOfMemoryError: Java heap space' when run it.
Why?How to solve it?
I have already faced with that problem. And i haven’t found solution for
it. The trouble is in implementation of java language and poi . Big
excel file consists of great number of little structures and size plenty
of them is about 1 - 8 bytes. Poi creates java object for each
structure. Empty java object in sun implementation has size of 8 bytes.
An object with 1-byte field is aligned to 16 bytes, 4 - bytes to 16, 9
bytes to 24 and etc. This lead to that : poi reads a documents with size
of 45 Mb(about 3000 000 objects), but poi object has size of 700 Mb.
I have solved that problem for reading with using "poi event based api"
. I have read only data and placed it in lists. This decreased object's
size from 700 to 160.
But still i don't know solution for file generation. I even think that,
may be, poi developers can't help you.
---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
Mailing List: http://jakarta.apache.org/site/mail2.html#poi
The Apache Jakarta Poi Project: http://jakarta.apache.org/poi/
