升级到最新的 JDK 后，我们(在某些机器上)遇到了一个奇怪的 OutOfMemoryException。

考虑这个简单的应用程序:

public class Test
{
    public static void main (String[] args) {
        try {
            java.text.SimpleDateFormat dateFormatter = new java.text.SimpleDateFormat("E dd/MM/yyyy HH:mm");
            System.out.println("formatted date: " + dateFormatter.format(new java.util.Date()));
        } catch (Exception x) {
            System.err.println(x);
            System.exit(1);
        }
    }
}

运行这个小程序会导致这个异常(即使用-Xmx2048M -Xms2048运行它):

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
    at java.util.Currency.readLongArray(Currency.java:657)
    at java.util.Currency.access$100(Currency.java:76)
    at java.util.Currency$1.run(Currency.java:211)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.util.Currency.<clinit>(Currency.java:192)
    at java.text.DecimalFormatSymbols.initialize(DecimalFormatSymbols.java:566)
    at java.text.DecimalFormatSymbols.<init>(DecimalFormatSymbols.java:94)
    at java.text.DecimalFormatSymbols.getInstance(DecimalFormatSymbols.java:157)
    at java.text.NumberFormat.getInstance(NumberFormat.java:767)
    at java.text.NumberFormat.getIntegerInstance(NumberFormat.java:439)
    at java.text.SimpleDateFormat.initialize(SimpleDateFormat.java:664)
    at java.text.SimpleDateFormat.<init>(SimpleDateFormat.java:585)
    at java.text.SimpleDateFormat.<init>(SimpleDateFormat.java:560)
    at Test.main(Test.java:5)

有人可以给我解释一下吗？

我们使用的java版本是:

java version "1.7.0_45"
Java(TM) SE Runtime Environment (build 1.7.0_45-b18)
Java HotSpot(TM) 64-Bit Server VM (build 24.45-b08, mixed mode)

当我们使用以前的版本时，我们没有问题:

java -version

java version "1.7.0_25"
Java(TM) SE Runtime Environment (build 1.7.0_25-b16)
Java HotSpot(TM) 64-Bit Server VM (build 23.25-b01, mixed mode)

Java 测试

formatted date: ma 21/10/2013 10:19

更新:在每个人都提到增加堆大小之前...我已经尝试过了:

java -Xmx2048M -Xms2048M 测试

Runtime.getRuntime().freeMemory(): 2048120480
Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
    at java.util.Currency.readLongArray(Currency.java:657)
    at java.util.Currency.access$100(Currency.java:76)
    at java.util.Currency$1.run(Currency.java:211)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.util.Currency.<clinit>(Currency.java:192)
    at java.text.DecimalFormatSymbols.initialize(DecimalFormatSymbols.java:566)
    at java.text.DecimalFormatSymbols.<init>(DecimalFormatSymbols.java:94)
    at java.text.DecimalFormatSymbols.getInstance(DecimalFormatSymbols.java:157)
    at java.text.NumberFormat.getInstance(NumberFormat.java:767)
    at java.text.NumberFormat.getIntegerInstance(NumberFormat.java:439)
    at java.text.SimpleDateFormat.initialize(SimpleDateFormat.java:664)
    at java.text.SimpleDateFormat.<init>(SimpleDateFormat.java:585)
    at java.text.SimpleDateFormat.<init>(SimpleDateFormat.java:560)
    at Test.main(Test.java:8)

最佳答案

我深入研究了 java.util.Currency 的代码。它在静态类初始化程序 block 中读取位于 Java JRE 中的资源文件。

String homeDir = System.getProperty("java.home");
try {
    String dataFile = homeDir + File.separator +
            "lib" + File.separator + "currency.data";
    DataInputStream dis = new DataInputStream(
        new BufferedInputStream(
        new FileInputStream(dataFile)));
    if (dis.readInt() != MAGIC_NUMBER) {
        throw new InternalError("Currency data is possibly corrupted");
    }
    formatVersion = dis.readInt();
    if (formatVersion != VALID_FORMAT_VERSION) {
        throw new InternalError("Currency data format is incorrect");
    }
    dataVersion = dis.readInt();
    mainTable = readIntArray(dis, A_TO_Z * A_TO_Z);
    int scCount = dis.readInt();
    scCutOverTimes = readLongArray(dis, scCount);

如您所见，它在 JRE/lib/currency.data 中读取。第四个整数包含 scCount。这个整数太高了。我猜该文件已损坏。尝试更换它。

关于java - OutOfMemoryException(升级到 JDK 7u45 后)，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/19489685/