java - garbage collector does not work -

i have program download stocks data internet , create stock objects contains stock meta data , array of historical prices.

at first ran on more 20000 stocks created them , entered them arraylist writing them db(all of them in 1 transaction). wasn't idea , before ended download stocks wanted program died because of outofmemory.

then decided after every 500 stocks adding arraylist write them db , clean arraylist(arraylist.clear() gc make it's "magic") , fill arraylist new 500 stocks , go through same proccess on again.

that didn't work either, , program died again because of outofmemory exception.

i thought problem may in else in code , made experiment , ran same code 1 little difference: after create each stock object not put arraylist , continue , create stock objects on again without adding them arraylist.

the result program didn't consume memory @ , make me confused , frustrated.

please me find out if wrong program.

here lines of code:

the first version:

arraylist<stock> stocksdata = new arraylist<stock>(); stock stock;  bufferedreader br = null; string line = "";  try {     br = new bufferedreader(new filereader(yahoo_stocks_symbols));     while ((line = br.readline()) != null) {         string[] stockmetadata = line.split(csv_split);         stock = new stock();         if (stockmetadata.length >= 4) {             stock.setsymbol(stockmetadata[0]);             stock.setname(stockmetadata[1]);             stock.setexchange(stockmetadata[2]);             stock.setcategory(stockmetadata[3]);             data_updater.updatestockdata(stock, fromdate, todate);             if (stock.gethistoricaldata() != null                     && stock.gethistoricaldata().size() > 0) {                 stocksdata.add(stock);             }         }     } } 

the second version:

arraylist<stock> stocksdata = new arraylist<stock>(); stock stock;  bufferedreader br = null; string line = "";  try {     br = new bufferedreader(new filereader(yahoo_stocks_symbols));     while ((line = br.readline()) != null) {         string[] stockmetadata = line.split(csv_split);         stock = new stock();         if (stockmetadata.length >= 4) {             stock.setsymbol(stockmetadata[0]);             stock.setname(stockmetadata[1]);             stock.setexchange(stockmetadata[2]);             stock.setcategory(stockmetadata[3]);             data_updater.updatestockdata(stock, fromdate, todate);             if (stock.gethistoricaldata() != null                     && stock.gethistoricaldata().size() > 0) {                 stocksdata.add(stock);             }         }         if (stocksdata.size() == 500) {             writingutils.getinstance().updatestocks(stocksdata);             stocksdata.clear();             // tried             //system.gc();         }     } } 

im adding more information:

stock fields:

protected string _symbol;  protected string _name;  protected string _exchange;  protected date _uptodate;  protected arraylist<dailydata> _historicaldata; 

dailydata fields:

private date _date;  private double _open;  private double _close;  private double _adjclose;  private double _high;  private double _low;  private double _volume; 

first start profiling application tool jvisualvm (which comes jdk) , pinpointing objects being retained in heap.

second, there no 'clean()' method on arraylist, not clear did prevent list growing indefinitely.

lastly, consider setting conditional breakpoint in program 'catch' when list growing beyond expectation.

edit: if you're asking :

'can outofmemoryerror due fact that:

protected arraylist<dailydata> _historicaldata; 

is growing , contributing memory pressure?'

the answer yes. have tried increase memory process? try running:

java -xms1g -xmx1g *yourprogram*

to see if still fails. may not have leak, may application needs more memory doing.