java.lang.OutOfMemoryError：超出GC开销限制 [英] java.lang.OutOfMemoryError: GC overhead limit exceeded

问题描述

我在一个程序中出现这个错误，该程序创建了几个（数十万个）每个有几个（15-20）个文本项的HashMap对象。这些字符串在提交到数据库之前已经被收集（没有分解成更小的数量）。

据Sun称，错误发生在如果时间太长被用于垃圾收集：如果超过98％的时间用于垃圾回收，并且只有不到2％的堆被恢复，则会抛出OutOfMemoryError。。

显然，可以使用命令行将参数传递给JVM以用于

• 增加堆大小，通过-Xmx1024m （或更多）或


• 通过-XX：-UseGCOverheadLimit完全禁用错误检查。

第一种方法工作正常，第二种方法在另一个java.lang.OutOfMemoryError中结束，这次是关于堆。

所以，question：is有没有任何程序化的替代方案，对于特定的用例（即几个小的HashMap对象）？例如，如果我使用HashMap clear（）方法，问题就会消失，但存储在HashMap中的数据也会消失！ ： - ）

这个问题也在

解决方案

你基本上没有足够的内存来顺利运行这个过程。想到这些选项：

1. 指定更多像上面提到的内存，尝试一些像 -Xmx512m first


2. 如果可能的话，一次处理 HashMap 对象的小批量


3. 如果您有很多重复的字符串，请使用 String.intern（） ，然后将它们放入 HashMap


4. 使用 HashMap（int initialCapacity，float loadFactor） 构造函数调整您的情况




I am getting this error in a program that creates several (hundreds of thousands) HashMap objects with a few (15-20) text entries each. These Strings have all to be collected (without breaking up into smaller amounts) before being submitted to a database.

According to Sun, the error happens "if too much time is being spent in garbage collection: if more than 98% of the total time is spent in garbage collection and less than 2% of the heap is recovered, an OutOfMemoryError will be thrown.".

Apparently, one could use the command line to pass arguments to the JVM for

• Increasing the heap size, via "-Xmx1024m" (or more), or
• Disabling the error check altogether, via "-XX:-UseGCOverheadLimit".

The first approach works fine, the second ends up in another java.lang.OutOfMemoryError, this time about the heap.

So, question: is there any programmatic alternative to this, for the particular use case (i.e., several small HashMap objects)? If I use the HashMap clear() method, for instance, the problem goes away, but so do the data stored in the HashMap! :-)

The issue is also discussed in a related topic in StackOverflow.

解决方案

You're essentially running out of memory to run the process smoothly. Options that come to mind:

1. Specify more memory like you mentioned, try something in between like -Xmx512m first
2. Work with smaller batches of HashMap objects to process at once if possible
3. If you have a lot of duplicate strings, use String.intern() on them before putting them into the HashMap
4. Use the HashMap(int initialCapacity, float loadFactor) constructor to tune for your case

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