See question 20 from the POI FAQ [1]. Accessing the same document objects from multiple threads is not supported.
[1] https://poi.apache.org/faq.html On Thu, Aug 23, 2018 at 3:47 AM Pavel Drankov <titant...@gmail.com> wrote: > Hi, > > I have an instance of SXSSFSheet and when I'm trying to fill it with > values concurrently, such exceptions occurs: > > java.util.ConcurrentModificationException: null > at java.util.TreeMap$PrivateEntryIterator.nextEntry(TreeMap.java:1211) > ~[na:1.8.0_152] > at java.util.TreeMap$EntryIterator.next(TreeMap.java:1247) ~[na:1.8.0_152] > at java.util.TreeMap$EntryIterator.next(TreeMap.java:1242) ~[na:1.8.0_152] > at org.apache.poi.xssf.streaming.SXSSFSheet.getRowNum(SXSSFSheet.java:1851) > ~[poi-ooxml-3.14.jar:3.14] > at org.apache.poi.xssf.streaming.SXSSFRow.getRowNum(SXSSFRow.java:218) > ~[poi-ooxml-3.14.jar:3.14] > at org.apache.poi.xssf.streaming.SXSSFCell.getRowIndex(SXSSFCell.java:84) > ~[poi-ooxml-3.14.jar:3.14] > at org.apache.poi.xssf.streaming.SXSSFCell.setHyperlink(SXSSFCell.java:649) > ~[poi-ooxml-3.14.jar:3.14] > > java.lang.NullPointerException: null > at > > org.apache.poi.xssf.streaming.AutoSizeColumnTracker.updateColumnWidths(AutoSizeColumnTracker.java:302) > ~[poi-ooxml-3.14.jar:3.14] > at > org.apache.poi.xssf.streaming.SXSSFSheet.flushOneRow(SXSSFSheet.java:1834) > ~[poi-ooxml-3.14.jar:3.14] > at org.apache.poi.xssf.streaming.SXSSFSheet.flushRows(SXSSFSheet.java:1813) > ~[poi-ooxml-3.14.jar:3.14] > at org.apache.poi.xssf.streaming.SXSSFSheet.createRow(SXSSFSheet.java:155) > ~[poi-ooxml-3.14.jar:3.14] > > I put synchronization on the object access and it works fine now, but is > not it an issue? Should the SXSSFCell and SXSSFSheet objects be thread > safe? > > Best wishes, > Pavel >
