blocks|key|853814|text|通常，在Java中将结构化文本转换为相应的数据结构时，需要的空间比输入文件的大小大得多。除了字符串所需的空间之外，与所使用的各种数据结构相关的开销也很大。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|853815|例如，每个String实例有大约32-40字节的额外开销-更不用说每个字符存储在两个字节中，这实际上使ASCII编码的空间需求增加了一倍。|offset|length|style|CODE|853816|然后，在结构中存储字符串时会有额外的开销。例如，为了在Map中存储String实例，您将需要大约16-32字节的额外开销，这取决于实现和测量使用情况的方式。|853817|6+6GB很可能不足以一次存储一个经过解析的2.6+6GB的XML文件……|853818|底线：|BOLD|853819|如果您正在内存中加载这么大的XML文件(例如，使用DOM解析器)，那么您可能做错了什么。像SAX这样的基于流的解析器应该有更适度的需求。|853820|或者，考虑将XML文件转换为更可用的文件格式，例如嵌入式数据库，甚至是实际的基于服务器的数据库。这将允许您处理更大的文档而不会出现问题。|853821|entityMap^0|0|5|6|0|R|3|X|6|0|0|0|3|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|V|8|@$D|W|E|X|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|Y|8|@$D|Z|E|10|F|G]|$D|11|E|12|F|G]]|9|@]|A|$]]|$1|J|3|K|5|6|7|13|8|@]|9|@]|A|$]]|$1|L|3|M|5|6|7|14|8|@$D|15|E|16|F|N]]|9|@]|A|$]]|$1|O|3|P|5|6|7|17|8|@]|9|@]|A|$]]|$1|Q|3|R|5|6|7|18|8|@]|9|@]|A|$]]|$1|S|3|-4|5|6|7|19|8|@]|9|@]|A|$]]]|T|$]]

In general, when converting structured text to the corresponding data structures in Java you need a lot more space than the size of the input file. There is a lot of overhead associated with the various data structures that are used, apart from the space required for the strings.

For example, each <code>String</code> instance has an additional overhead of about 32-40 bytes - not to mention that each character is stored in two bytes, which effectively doubles the space requirements for ASCII-encoded XML.

Then you have additional overhead when storing the String in a structure. For example, in order to store a <code>String</code> instance in a <code>Map</code> you will need about 16-32 bytes of additional overhead, depending on the implementation and how you measure the usage.

It is quite possible that 6GB is just not enough to store a parsed 2.6GB XML file at once...

Bottom line:

If you are loading such a large XML file in memory (e.g. using a DOM parser) you are probably doing something wrong. A stream-based parser such as SAX should have far more modest requirements.

Alternatively consider transforming the XML file into a more usable file format, such as an embedded database - or even an actual server-based database. That would allow you to process far larger documents without issues.

blocks|key|4687551|text|您应该避免一次将整个xml加载到内存中，而是使用可以处理大量xml的专用类。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4687552|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

You should avoid loading the entire xml into memory at once and instead use a specialized class that can deal with large amounts of xml.

blocks|key|191612|text|这里可能有几个不同的问题。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|191613|但对于初学者来说：|191614|1)如果您使用的是64位操作系统，请确保使用的是64位JVM|191615|2)确保您的代码尽快关闭您打开的所有资源。|191616|3)显式地将对已完成的大型对象的引用设置为"null“。|191617|..。还有..。|191618|4)熟悉JConsole或VisualVM|offset|length|191619|191620|http://www.ibm.com/developerworks/library/j-5things7/|unordered-list-item|191621|http://visualvm.java.net/api-quickstart.html|191622|191623|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.oracle.com/javase/6/docs/technotes/guides/management/jconsole.html|1|http://docs.oracle.com/javase/6/docs/technotes/guides/visualvm/index.html|2|3^0|0|0|0|0|0|0|4|8|0|D|8|1|0|0|0|1H|2|0|0|18|3|0|0^^$0|@$1|2|3|4|5|6|7|18|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|19|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|1A|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|1B|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|1C|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|1D|8|@]|9|@]|A|$]]|$1|L|3|M|5|6|7|1E|8|@]|9|@$N|1F|O|1G|1|1H]|$N|1I|O|1J|1|1K]]|A|$]]|$1|P|3|-4|5|6|7|1L|8|@]|9|@]|A|$]]|$1|Q|3|R|5|S|7|1M|8|@]|9|@$N|1N|O|1O|1|1P]]|A|$]]|$1|T|3|U|5|S|7|1Q|8|@]|9|@$N|1R|O|1S|1|1T]]|A|$]]|$1|V|3|-4|5|6|7|1U|8|@]|9|@]|A|$]]|$1|W|3|-4|5|6|7|1V|8|@]|9|@]|A|$]]]|X|$Y|$5|Z|10|11|A|$12|13]]|14|$5|Z|10|11|A|$12|15]]|16|$5|Z|10|11|A|$12|R]]|17|$5|Z|10|11|A|$12|U]]]]

There are potentially several different issues here.

But for starters:

1) If you're on a 64-bit OS, make sure you're using a 64-bit JVM

2) Make sure your code closes all resources you open as promptly as possible.

3) Explicitly set references to large objects you're done with to "null".

... AND ...

4) Familiarize yourself with <a href="http://docs.oracle.com/javase/6/docs/technotes/guides/management/jconsole.html" rel="nofollow">JConsole</a> or <a href="http://docs.oracle.com/javase/6/docs/technotes/guides/visualvm/index.html" rel="nofollow">VisualVM</a>:

<ul>
<li><a href="http://www.ibm.com/developerworks/library/j-5things7/" rel="nofollow">http://www.ibm.com/developerworks/library/j-5things7/</a></li>
<li><a href="http://visualvm.java.net/api-quickstart.html" rel="nofollow">http://visualvm.java.net/api-quickstart.html</a></li>
</ul>

blocks|key|4204854|text|您不能将2.6+GB的XML图像作为仅有6+GB的文档加载。正如jhordo建议的那样，这个比率更有可能是12+:+1。这是因为每个字节都会变成一个16位的字符，每个标签、属性和值都会变成一个至少有32字节开销的字符串。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4204855|相反，您应该使用SAX或基于事件的解析器来逐步处理文件。这样，它将只保留您需要保留的数据量。如果您可以在一次处理中处理所有内容，则不需要保留任何内容。|4204856|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

You can't load a 2.6 GB XML image as a document with just 6 GB. As jhordo suggests, the ratio is more likely to be be 12 to 1. This is because every byte turns into a 16-bit character and every tag, attribute and value turns into a String with at least 32 bytes of overhead.

Instead what you should do is use a SAX or event based parser to process the file progressively. This way it will only keep as much data as you need to retain. If you can process everything in one pass, you won't need to retain anything.

I am reading a single XML file of size- 2.6GB-- the size of JVM is 6GB.

However I am still getting a Heap Space out of memory error?

What am I doing wrong here...

For reference, I output the max memory and free memory properties of the JVM--

The max memory was shown as approx 5.6GB, but free memory was shown as only 90MB... Why is only 90MB being shown as free, esp. when I have not even started any processing... I have just started the program?

getting heap space out of memory error- how is java heap memory used

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我正在读取一个大小为2.6 6GB的XML文件-- JVM的大小是6 6GB。然而，我仍然得到一个堆空间内存不足的错误？我到底做错了什么.作为参考，我输出了JVM的最大内存和空闲内存属性--最大内存显示为大约5.6 as，但可用内存仅显示为90MB...为什么只有90MB显示为空闲，特别是当我还没有开始任何处理的时候....

问获取内存不足的堆空间错误-如何使用java堆内存
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