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https://issues.apache.org/jira/browse/PDFBOX-4818?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Tilman Hausherr updated PDFBOX-4818:
------------------------------------
Comment: was deleted
(was: I don't see where you are closing the "doc" PDDocument object in
"render()".)
> Is it possible to render a pdf to multi pic with PdfRenderer multi threads?
> ---------------------------------------------------------------------------
>
> Key: PDFBOX-4818
> URL: https://issues.apache.org/jira/browse/PDFBOX-4818
> Project: PDFBox
> Issue Type: Improvement
> Components: Rendering
> Affects Versions: 2.0.19
> Reporter: jiangpeiheng
> Priority: Major
>
> Hi, pdfbox developers.
> I'm using pdfbox to render my pdf file to multi jpg pictures. I've read the
> faq, and found that the PDDocument is not thread safe which means operating
> same PDDocument with multi threads risks.
> The method now I'm using is generate multi PDDocuments to render different
> parts of pdf to speed up the render process. However, it costs much memory.
> And when meeting some big pdf (400+ pages), it may occur OOM.
> So I'm wondering, what is the best way to use pdfbox to render a pdf?
> Here is my code for rendering:
> {code:java}
> package com.bytedance.esign.utils.pdf;
> import com.bytedance.esign.constants.enums.ResponseCode;
> import com.bytedance.esign.exception.EsignException;
> import com.bytedance.esign.threadpool.ThreadPoolManager;
> import com.bytedance.esign.utils.ContractLoadingRecorder;
> import com.google.common.collect.Lists;
> import lombok.AllArgsConstructor;
> import lombok.Data;
> import lombok.extern.slf4j.Slf4j;
> import org.apache.commons.io.IOUtils;
> import org.apache.pdfbox.io.MemoryUsageSetting;
> import org.apache.pdfbox.pdmodel.PDDocument;
> import org.apache.pdfbox.rendering.PDFRenderer;
> import javax.imageio.ImageIO;
> import java.awt.image.BufferedImage;
> import java.io.ByteArrayInputStream;
> import java.io.ByteArrayOutputStream;
> import java.io.IOException;
> import java.io.InputStream;
> import java.util.ArrayList;
> import java.util.Collections;
> import java.util.List;
> import java.util.concurrent.CompletableFuture;
> import java.util.function.Supplier;
> /**
> * pdfbox 工具
> *
> * @author jiangpeiheng create on 2020/1/15
> */
> @Slf4j
> public class PdfBoxUtil {
> private static final String LOG_PERFIX = "PDF_BOX_UTIL";
> private static final int MAX_PAGE_FOR_SINGLE_RENDER_TASK = 15;
> static {
>
> System.setProperty("org.apache.pdfbox.rendering.UsePureJavaCMYKConversion",
> "true");
> }
> /**
> * pdf转图片
> *
> * @param is
> * @param contractId
> * @return
> */
> public static List<byte[]> pdfToJpg(InputStream is, String contractId) {
> long start = System.currentTimeMillis();
> try {
> byte[] docBytes = IOUtils.toByteArray(is);
> PDDocument doc = load(docBytes); // 只为获取页数
> int pageCount = doc.getPages().getCount();
> close(doc);
> doc = null; // 方便gc
> // 向redis上报总页数
> ContractLoadingRecorder.setTotalPage(contractId, pageCount);
> // 拆任务
> List<CompletableFuture<List<byte[]>>> futures =
> splitTask(docBytes, pageCount, contractId);
> List<byte[]> images = Lists.newArrayList();
> futures.forEach(future -> images.addAll(future.join()));
> // 判断最终切割的页数
> if (pageCount != images.size()) {
> log.error("[{}]PDF渲染图片，最终获取到的图片页数与预期页数不符，expect:{},
> actual:{}",
> LOG_PERFIX, pageCount, images.size());
> throw new EsignException(ResponseCode.SYSTEM_ERROR.getCode(),
> "PDF切图，最终图片页数与预计页数不符！");
> }
> log.info("[{}]PDF渲染图片整体流程成功", LOG_PERFIX);
> return images;
> } catch (Exception e) {
> log.error("[{}]PDF渲染图片整体流程异常, contractId:{}, e:",
> LOG_PERFIX, contractId, e);
> return Collections.emptyList();
> } finally {
> log.info("[{}]PDF渲染图片整体流程完成, contractId:{}, cost:{}",
> LOG_PERFIX, contractId, System.currentTimeMillis() -
> start);
> }
> }
> private static List<CompletableFuture<List<byte[]>>> splitTask(byte[]
> pdfBytes, int pages, String contractId) {
> List<CompletableFuture<List<byte[]>>> futures = Lists.newArrayList();
> int start = 0;
> int end = Math.min(start + MAX_PAGE_FOR_SINGLE_RENDER_TASK, pages);
> while (start != end && end <= pages) {
> RenderTask task = new RenderTask(pdfBytes, start, end,
> contractId);
> futures.add(CompletableFuture.supplyAsync(task,
> ThreadPoolManager.PDF_RENDER_EXECUTOR));
> start = end;
> end = Math.min(start + MAX_PAGE_FOR_SINGLE_RENDER_TASK, pages);
> }
> return futures;
> }
> @Data
> @AllArgsConstructor
> private static class RenderTask implements Supplier<List<byte[]>> {
> private byte[] pdfBytes;
> private int start;
> private int end;
> private String contractId;
> @Override
> public List<byte[]> get() {
> return render(pdfBytes, start, end, contractId);
> }
> }
> private static List<byte[]> render(byte[] pdfBytes, int start, int end,
> String contractId) {
> long startTime = System.currentTimeMillis();
> try (
> PDDocument doc = load(pdfBytes)
> ) {
> log.info("[{}]载入并发线程的PDDocument耗时:{}",
> LOG_PERFIX, System.currentTimeMillis() - startTime);
> PDFRenderer renderer = new PDFRenderer(doc);
> List<byte[]> images = new ArrayList<>();
> for (int i = start; i < end; i++) {
> BufferedImage bim = renderer.renderImageWithDPI(i, 200);
> images.add(transformImage(bim));
> long subStart = System.currentTimeMillis();
> ContractLoadingRecorder.incrRenderedPage(contractId);
> log.info("[{}]上报新增渲染页数耗时:{}",
> LOG_PERFIX, System.currentTimeMillis() - subStart);
> }
> log.info("[{}]单task渲染PDF成功, start:{}, end:{}, pages:{}",
> LOG_PERFIX, start, end, images.size());
> return images;
> } catch (Exception e) {
> log.error("[{}]单task渲染PDF异常, start:{}, end:{}, e:",
> LOG_PERFIX, start, end, e);
> return Collections.emptyList();
> } finally {
> log.info("[{}]单task渲染PDF完成, start:{}, end:{}, cost:{}",
> LOG_PERFIX, start, end, System.currentTimeMillis() -
> startTime);
> }
> }
> private static byte[] transformImage(BufferedImage bim) throws
> IOException {
> ByteArrayOutputStream os = new ByteArrayOutputStream();
> ImageIO.write(bim, "jpg", os);
> return os.toByteArray();
> }
> private static PDDocument load(byte[] docBytes) throws IOException {
> return PDDocument.load(new ByteArrayInputStream(docBytes),
> MemoryUsageSetting.setupTempFileOnly());
> }
> private static void close(PDDocument doc) throws IOException {
> if (doc == null) {
> return;
> }
> doc.close();
> }
> }
> {code}
> Thanks
> Jiangpeiheng
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