java - XSSFWorkbook stays in memory -

i using apache pio version 3.14 export data excel. problem uses lot of memory. visualvm noticed data in oldgen shoots ~80m ~400m 800k export file , stays there. if repeat operation on , on keeps growing. seems xssfworkbook never garbage collected , holds references cells/sheets excel file. tried using sxssfworkbook memory usage similar. there way reduce memory usage? or how can dispose xssfworkbook. tried closing workbook , making reference null, not help

today saw same problem in our application. workbook cells lands in old generation , never deleted. analyze problem created application creates workbook 10 rows each row has 10 cells.

then tried move code separate thread.

still objects remain in memory workbook, sheet, rows , cells gone. here simplified code sample show how tested it.

public static void main(string[] args) {     runnable runnable = new runnable() {         @override         public void run() {             workbook workbook = null;             fileoutputstream fileoutputstream = null;              try {                 workbook = new xssfworkbook();                 sheet sheet = workbook.createsheet();                 row row = sheet.createrow(0);                 cell cell = row.createcell(0);                 cell.setcellvalue("test");                 fileoutputstream = new fileoutputstream(new file("/tmp/workbook.xlsx"));                 workbook.write(fileoutputstream);             } catch (ioexception e) {                 e.printstacktrace();             } {                 if (workbook != null) {                     try {                         workbook.close();                     } catch (ioexception e) {                         e.printstacktrace();                     }                 }                  if (fileoutputstream != null) {                     try {                         fileoutputstream.close();                     } catch (ioexception e) {                         e.printstacktrace();                     }                 }             }         }     };      thread thread = new thread(runnable);     thread.start();      // infinite loop monitor visualvm     for(;;); }