22-Feb-2017 16:41:32.141 SEVERE [http-nio-8081-ClientPoller-0] org.apache.tomcat.util.net.NioEndpoint$Poller.run
 java.lang.OutOfMemoryError: Java heap space
        at java.util.Collections$UnmodifiableCollection.iterator(Collections.java:1038)
        at org.apache.tomcat.util.net.NioEndpoint$Poller.timeout(NioEndpoint.java:1287)
        at org.apache.tomcat.util.net.NioEndpoint$Poller.run(NioEndpoint.java:1094)
        at java.lang.Thread.run(Thread.java:745)

2017-02-22 16:41:35,731 ERROR [conversion-thread-0] [plugins.conversion.impl.TimeoutConversionRunnable] run Cannot convert. Execution error:
 -- url: /display/DEMO/NEW+XLS+test | page: 917505 | traceId: 4ecd169c1d90bb85 | userName: admin | referer: http://ec2-54-229-125-162.eu-west-1.compute.amazonaws.com:8081/ | action: viewpage
java.lang.OutOfMemoryError: Java heap space
        at com.aspose.cells.zth.b(Unknown Source)
        at com.aspose.cells.zth.a(Unknown Source)
        at com.aspose.cells.zth.a(Unknown Source)
        at com.aspose.cells.zth.a(Unknown Source)
        at com.aspose.cells.zth.a(Unknown Source)
        at com.aspose.cells.zbwm.a(Unknown Source)
        at com.aspose.cells.SheetRender.<init>(Unknown Source)
        at com.atlassian.plugins.conversion.convert.image.CellsConverter.generateThumbnailDirect(CellsConverter.java:102)
        at com.atlassian.confluence.plugins.conversion.impl.runnable.JVMConversionRunnable.generateThumbnail(JVMConversionRunnable.java:109)
        at com.atlassian.confluence.plugins.conversion.impl.runnable.JVMConversionRunnable.doWork(JVMConversionRunnable.java:77)
        at com.atlassian.confluence.plugins.conversion.impl.runnable.ConversionRunnable.run(ConversionRunnable.java:36)
        at com.atlassian.confluence.plugins.conversion.impl.runnable.JVMConversionRunnable.run(JVMConversionRunnable.java:22)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745)