Spring Boot内存消耗增加到超过-Xmx选项

问题描述

我注意到Spring Boot应用程序不遵守通过Xmx选项设置的内存量.例如:java -Xss64m -Xmx64m -jar test.jar

I noticed Spring Boot application does not obey the amount of memory set via Xmx option.For example: java -Xss64m -Xmx64m -jar test.jar

我还在控制台上打印了启动时应用程序实际使用的内存量，并显示:最大内存:61M

I also printed on console the amount of memory really used by application at startup, and shows:Max memory: 61M

long maxBytes = Runtime.getRuntime().maxMemory();
System.out.println("Max memory: " + maxBytes / 1024 / 1024 + "M");

当我在访问任何网页之前打开Windows进程时，它显示+ -105M，那么Java怎么说61M?

When I open Windows processes before accessing any web page, it shows +-105M, so how can Java say 61M?

访问任何网页后，它从+ -125M变为+ -135M.为什么会有这样的增加?它应该提供"java.lang.OutOfMemoryError:PermGen空间"，但不要以这种方式增加.

After accessing any web page it goes from +-125M to +-135M. Why is there such increase? It should give "java.lang.OutOfMemoryError: PermGen space" but do not increase this way.

如果许多应用程序可能耗尽服务器的内存，这会让我感到担忧.顺便说一句，我正在使用Java 1.8_45

It makes me get worried, if many applications could run out of memory at the server. By the way, I am using Java 1.8_45

推荐答案

在监视Spring Boot应用程序之后，我发现了一些可能的原因，例如:

After monitoring the Spring Boot application, I found out some possible reasons such as:

1. http线程数(Undertow开始于每个线程约50个线程默认值，但您可以通过属性增加/减少所需的线程数量)
2. 通过JNI访问本机例程(.dll，.so)
3. 静态变量
4. 使用缓存(内存缓存，ehcache等)
5. 如果VM是32位或64位，则64位会使用更多的内存来运行同一应用程序，因此，如果您不需要大于1.5GB的堆，请使应用程序的运行时间保持在32位以上以节省内存.

1. Number of http threads (Undertow starts around 50 threads perdefault, but you can increase / decrease via property the amount of threads needed)
2. Access to native routines (.dll, .so) via JNI
3. Static variables
4. Use of cache (memcache, ehcache, etc)
5. If a VM is 32 bit or 64 bit, 64 bit uses more memory to run the same application, so if you don't need a heap bigger than 1.5GB, so keep your application runnnig over 32 bit to save memory.

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