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POMemory usage of a GWT application
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  1. POMemory usage of a GWT application
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    copied!<p>I'm currently working on a GWT application as a proof of technology for future projects. I like the way of building my AJAX code in Java instead of JavaScript. But I seem to be running into a memory problem when I repeat calls to an RPC service. The browser memory usage keeps growing and growing. </p> <p>When searching Google I keep reading about how great GWT is and that its impossible to get memory leaks so can anyone explain why my browser (Firefox and Chromium) memory is rocketing?</p> <p>Thanks in advance for helping me, Bram</p> <p>The code:</p> <pre><code>... class ExampleTable extends Composite private RPCService rpcService; private Timer tableUpdater; public ExampleTable(){ ... Init timer and RPC Service ... Add components initWidget(); } private void getTableDataFromRPCService() { this.rpcService.getData(new AsyncCallback&lt;ArrayList&lt;Data&gt;&gt;() { @Override public void onSuccess(ArrayList&lt;Data&gt; result) { ExampleTable.this.updateTable(result); } @Override public void onFailure(Throwable caught) { //Do nothing } }); } private void updateTable(ArrayList&lt;Data&gt; tableData){ ... Update the table } private void startUpdateTask() { this.serviceUpdater = new Timer() { @Override public void run() { ExampleTable.this.getTableDataFromRPCService(); } }; serviceUpdater.scheduleRepeating(2000); } } </code></pre> <p><strong>EDIT:</strong></p> <p>I've spent some time to write a test application which can be downloaded <a href="http://www.pouwelse.com/GWTMemoryIssue.zip" rel="nofollow noreferrer">here</a>. I ran the application for about half an hour with the table update enabled after that Firefox took about 350MB of memory. I also ran the test with the update table disabled for an hour memory usage in Firefox went to little over 100MB.</p> <p>(To run this sample you need the Google visualization API for GWT which can be downloaded from Google but I'm not allowed to post the link because of a new user policy )</p> <p>I just got home from work and start another test without the table data update to see if memory usage keeps increasing or if it stops at a certain point.</p> <p>This is the client implementation class (GWTMemoryIssue.java):</p> <pre><code>public class GWTMemoryIssue implements EntryPoint { //Run with or without table private static final boolean WITH_TABLE = false; private final TestServiceAsync rpcService = GWT.create(TestService.class); private Panel panel; private Timer timer; private Table table; public void onModuleLoad() { RootPanel rootPanel = RootPanel.get(); this.panel = new VerticalPanel(); this.panel.setSize("100%", "100%"); rootPanel.add(panel); if (WITH_TABLE) { loadTable(); }else{ startUpdateTask(); } } private void startUpdateTask() { this.timer = new Timer() { @Override public void run() { GWTMemoryIssue.this.getTableData(); } }; this.timer.scheduleRepeating(2000); } public void loadTable() { Runnable onLoadCallback = new Runnable() { public void run() { GWTMemoryIssue.this.table = new Table(createTableData(), createTableOptions()); GWTMemoryIssue.this.table.setSize("100%", "100%"); GWTMemoryIssue.this.panel.add(GWTMemoryIssue.this.table); GWTMemoryIssue.this.startUpdateTask(); } }; VisualizationUtils.loadVisualizationApi(onLoadCallback, Table.PACKAGE); } private Options createTableOptions() { Options options = Options.create(); return options; } private DataTable createTableData() { DataTable data = DataTable.create(); data.addColumn(ColumnType.STRING, "Name"); data.addColumn(ColumnType.NUMBER, "Intval 1"); data.addColumn(ColumnType.NUMBER, "Intval 2"); data.addColumn(ColumnType.NUMBER, "Intval 3"); return data; } private void getTableData() { rpcService.getListOfItems(new AsyncCallback&lt;ArrayList&lt;ListItem&gt;&gt;(){ public void onFailure(Throwable caught) { // Do nothing } public void onSuccess(ArrayList&lt;ListItem&gt; result) { if (WITH_TABLE){ GWTMemoryIssue.this.updateTableData(result); }else{ //Ignore the data from the server } } }); } private void updateTableData(ArrayList&lt;ListItem&gt; result) { DataTable data = createTableData(); data.addRows(result.size()); int row = 0; for (ListItem li : result) { data.setValue(row, 0, li.getName()); data.setValue(row, 1, li.getIntVal()); data.setValue(row, 2, li.getIntSecondVal()); data.setValue(row, 3, li.getThirdIntVal()); row++; } this.table.draw(data, createTableOptions()); } } </code></pre>
 

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