poi-ooxml/src/test/java/org/apache/poi/xssf/util/MemoryUsage.java

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   contributor license agreements.  See the NOTICE file distributed with
   this work for additional information regarding copyright ownership.
   The ASF licenses this file to You under the Apache License, Version 2.0
   (the "License"); you may not use this file except in compliance with
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       http://www.apache.org/licenses/LICENSE-2.0

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   distributed under the License is distributed on an "AS IS" BASIS,
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package org.apache.poi.xssf.util;

import static org.junit.jupiter.api.Assertions.assertNotNull;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.ss.usermodel.WorkbookFactory;
import org.apache.poi.ss.util.CellReference;
import org.junit.jupiter.api.Disabled;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.ValueSource;
import org.openxmlformats.schemas.spreadsheetml.x2006.main.CTCell;
import org.openxmlformats.schemas.spreadsheetml.x2006.main.CTRow;
import org.openxmlformats.schemas.spreadsheetml.x2006.main.CTSheetData;
import org.openxmlformats.schemas.spreadsheetml.x2006.main.CTWorksheet;
import org.openxmlformats.schemas.spreadsheetml.x2006.main.STCellType;

/**
 * Mixed utilities for testing memory usage in XSSF
 */
@Disabled("only for manual tests")
@SuppressWarnings("InfiniteLoopStatement")
public class MemoryUsage {
    private static final int NUM_COLUMNS = 255;

    private static void printMemoryUsage(String msg) {
        System.out.println(" Memory (" + msg + "): " + Runtime.getRuntime().totalMemory()/(1024*1024) + "MB");
    }

    /**
     * Generate a spreadsheet until OutOfMemoryError using low-level OOXML XmlBeans.
     * Similar to {@link #numberSpreadsheet(org.apache.poi.ss.usermodel.Workbook, int)}
     *
     * <p>
     *
     * @param numCols  the number of columns in a row
     */
    public static void xmlBeans(int numCols) {
        int i = 0, cnt = 0;
        printMemoryUsage("before");

        CTWorksheet sh = CTWorksheet.Factory.newInstance();
        CTSheetData data = sh.addNewSheetData();
        try {
            for (i = 0; ; i++) {
                CTRow row = data.addNewRow();
                row.setR(i);
                for (int j = 0; j < numCols; j++) {
                    CTCell cell = row.addNewC();
                    cell.setT(STCellType.N);
                    cell.setV(String.valueOf(j));
                    cnt++;
                }
            }
        } catch (OutOfMemoryError er) {
            System.out.println("Failed at row=" + i + ", objects: " + cnt);
        } finally {
            printMemoryUsage("after");
        }
    }

    /**
     * Generate detached (parentless) Xml beans until OutOfMemoryError
     *
     * @see #testXmlAttached()
     */
    @Test
    void testXmlDetached() {
        List<CTRow> rows = new ArrayList<>();
        int i = 0;
        try {
            for(;;) {
                //create a standalone CTRow bean
                CTRow r = CTRow.Factory.newInstance();
                assertNotNull(r);
                r.setR(++i);
                rows.add(r);
            }
        } catch (OutOfMemoryError er) {
            System.out.println("Failed at row=" + i + " from " + rows.size() + " kept.");
        } finally {
            printMemoryUsage("after");
        }
    }

    /**
     * Generate attached (having a parent bean) Xml beans until OutOfMemoryError.
     * This is MUCH more memory-efficient than {@link #testXmlDetached()}
     *
     * @see #testXmlAttached()
     */
    @Test
    void testXmlAttached() {
        printMemoryUsage("before");
        List<CTRow> rows = new ArrayList<>();
        int i = 0;
        //top-level element in sheet.xml
        CTWorksheet sh = CTWorksheet.Factory.newInstance();
        CTSheetData data = sh.addNewSheetData();
        try {
            for(;;) {
                //create CTRow attached to the parent object
                CTRow r = data.addNewRow();
                assertNotNull(r);
                r.setR(++i);
                rows.add(r);
            }
        } catch (OutOfMemoryError er) {
            System.out.println("Failed at row=" + i + " from " + rows.size() + " kept.");
        } finally {
            printMemoryUsage("after");
        }
    }

    /**
     * Generate a spreadsheet until OutOfMemoryError
     * cells in even columns are numbers, cells in odd columns are strings
     */
    @ParameterizedTest
    @ValueSource(booleans = {false, true})
    void testMixed(boolean useXSSF) throws IOException {
        int i=0, cnt=0;
        try (Workbook wb = WorkbookFactory.create(useXSSF)) {
            printMemoryUsage("before");
            Sheet sh = wb.createSheet();
            for(i=0; ; i++) {
                Row row = sh.createRow(i);
                for(int j=0; j < NUM_COLUMNS; j++) {
                    Cell cell = row.createCell(j);
                    assertNotNull(cell);
                    if(j % 2 == 0) {
                        cell.setCellValue(j);
                    } else {
                        cell.setCellValue(new CellReference(j, i).formatAsString());
                    }
                    cnt++;
                }
            }
        } catch (OutOfMemoryError er) {
            System.out.println("Failed at row=" + i + ", objects : " + cnt);
        } finally {
            printMemoryUsage("after");
        }
    }

    /**
     * Generate a spreadsheet who's all cell values are numbers.
     * The data is generated until OutOfMemoryError.
     * <p>
     * as compared to {@link #mixedSpreadsheet(org.apache.poi.ss.usermodel.Workbook, int)},
     * this method does not set string values and, hence, does not involve the Shared Strings Table.
     * </p>
     *
     * @param wb        the workbook to write to
     * @param numCols   the number of columns in a row
     */
    @ParameterizedTest
    @ValueSource(booleans = {false, true})
    void testNumberHSSF(boolean useXSSF) throws IOException {
        int i=0, cnt=0;
        try (Workbook wb = WorkbookFactory.create(useXSSF)) {
            printMemoryUsage("before");
            Sheet sh = wb.createSheet();
            for(i=0; ; i++) {
                Row row = sh.createRow(i);
                assertNotNull(row);
                for(int j=0; j < NUM_COLUMNS; j++) {
                    Cell cell = row.createCell(j);
                    cell.setCellValue(j);
                    cnt++;
                }
            }
        } catch (OutOfMemoryError er) {
            System.out.println("Failed at row=" + i + ", objects : " + cnt);
        } finally {
            printMemoryUsage("after");
        }
    }
}