pdfwriter潜在的内存泄漏

Question

我遇到了垃圾回收错误：java.lang.OutOfMemoryError：超出了我要解决的GC开销限制。

在日志中，生成PDF报告时我看到一个潜在的问题。 这段代码可能已经超过2年了。问题开始于两天前。

这段代码会导致内存泄漏吗？我更担心作者接受一个输出流并且它没有被关闭。 Doc正在关闭，是否足够？这段代码已经运行了好几年了。

在下面的代码编写器中被刷新但未关闭。这是潜在的内存泄漏吗？

  public void formatAndStream(OutputStream out) throws Exception {
    // Translate order to something more manageable.
    // Only the reports know which fields have meaning to them, so delegate this.
    List<FormField> ffs = buildFieldOrder();

    /**
     * Note on HeaderFooter and iText's built-in setHeader() setFooter() **
     * These can only contain text and so do not meet all our needs.
     * We must instead manually build a header and upper footer.
     */
    doc = new Document(pageSize);
    doc.addAuthor(I18.N("repfmt.pdfAuthor"));
    doc.addTitle(pdfTitle);
    doc.addCreationDate();
    doc.addProducer();

    // Build our PDF writer Listeners.
    // DocListener is too generic.
    PdfPageEventHelper list = new PdfPageEventHelper() {
        public void onStartPage(PdfWriter writer, Document document) {
            doStartPage(writer, document);
        }

        public void onEndPage(PdfWriter writer, Document document) {
            try {
                prepareForNextPage(document);
            } catch (Exception e) {
                System.err.println("Error preparing for page " + pageNumber);
                e.printStackTrace();
            }
        }
    };

    // Configure our PDF output.
    writer = PdfWriter.getInstance(doc, out);
    createDate = new Date();
    writer.setPageEvent(list);

    /*
    Margins
        Margins when set apply to the NEXT page to be written.
        Ergo, you must set margins for page 1 with prescient knowledge of the first section to be rendered.
        Each margin set thereafter should occur on end page.
        Subsect header renders must occur on begin page.
     */
    currentReport = findNextCareSubsection(ffs, true);
    currentSubsection = createSubsection(currentReport);
    prepareForNextPage(doc);

    // open the doc for writing
    doc.open();

    try {
        // Write the first section (it's special)
        if (currentSubsection != null) {
            currentSubsection.write(doc, docWidth, writer);
        }

        boolean pageBreakNeeded = false;
        // Iterate the elements in order, rendering them to the PDF output.
        for (FormField ff : ffs) {
            currentReport = null;
            currentSubsection = null;
            if (ff instanceof GeneralField) {
                GeneralField gf = (GeneralField)ff;
                switch (gf) {
                    case Pagebreak:
                        pageBreakNeeded = true;
                        break;
                    default:
                        System.err.println("Dropping unsupported GeneralField:  " + gf);
                }
            } else {
                SubsectionRenderer sr = this.createSubsection(ff);
                if (sr != null) {
                    currentReport = ff;
                    currentSubsection = sr;
                    // If we can fit the subsection's first header on this page, add() it.
                    // If we cannot, break the page.
                    // subsequent header paints must happen as part of a margin set/fill operation
                    float height = currentSubsection.getNextPageHeaderHeight(docWidth);
                    if (!pageBreakNeeded && Util.hasAtLeast(doc, writer, height)) {
                        currentSubsection.writeHeader(doc, docWidth);  // first hit is here
                    } else {
                        doc.newPage();
                        pageBreakNeeded = false;
                    }

                    if (pageBreakNeeded) {   // second hit here
                        doc.newPage();
                        pageBreakNeeded = false;
                    }

                    currentSubsection.write(doc, docWidth, writer);
                }
            }
        }
    } catch (Exception t) {
        doc.add(new Paragraph(I18.N("repfmt.errorMsg"), Defaults.FONT_ERROR));
        throw t;
    } finally {
        try {
            writer.flush();
            doc.close();
        } catch (Throwable t) {
           // prevent stream close exceptions from masking real exceptions
           System.err.println(I18.N("repfmt.4") + t);
        }
    }
}