在 Mac-OS X 10.8 中限制进程的内存分配 [英] Limit Memory allocation to a process in Mac-OS X 10.8

问题描述

我想控制最大内存，一个进程可以在 Mac-OS X 10.8 中使用.我觉得设置 ulimit -v 应该可以实现目标，但似乎并非如此.我尝试了以下简单的命令:

I would like to control the maximum memory, a process can use in Mac-OS X 10.8. I feel that setting ulimit -v should achieve the goals but doesn't seem to be the case. I tried following simple commands :

    ulimit -m 512

    java -Xms1024m -Xmx2048m SomeJavaProgram

我假设第二个命令应该失败，因为 Java 进程将通过为自己保留 1024MB 内存开始，但它会平静地通过.在我的示例程序中，我尝试使用以下代码片段分配超过 1024MB:

I was assuming that 2nd command should fail as Java Process will start by keeping 1024MB of memory for itself but it passes peacefully. Inside my Sample program, I try allocating more than 1024MB using following code snippet:

System.out.println("Allocating 1 GB of Memory");
List<byte[]> list = new LinkedList<byte[]>();
list.add(new byte[1073741824]); //1024 MB
System.out.println("Done....");

这两个程序都可以毫无问题地执行.我们如何控制 Mac-OS X 中程序的最大内存分配?

Both these programs get executed without any issues. How can we control the max memory allocation for a program in Mac-OS X?

推荐答案

我不确定您是否还需要回答这个问题，但这里是答案，以防其他人碰巧遇到同样的问题.

I'm not sure if you still need the question answered, but here is the answer in case anyone else happens to have the same question.

ulimit -m 严格限制常驻内存，而不是进程可以从操作系统请求的内存量.

ulimit -m strictly limits resident memory, and not the amount of memory a process can request from the operating system.

ulimit -v 将限制进程可以从操作系统请求的虚拟内存量.

ulimit -v will limit the amount of virtual memory a process can request from the operating system.

例如...

#include <stdio.h>
#include <stdlib.h>


int main(int argc, char* argv[]) {

    int size = 1 << 20;

    void* memory = NULL;

    memory = malloc(size);

    printf("allocated %i bytes...\n", size);

    return 0; 

}

ulimit -m 512
./memory
allocated 1048576 bytes...

ulimit -v 512
./memory
Segmentation fault

如果您执行 ulimit -a，它应该提供子进程所有当前限制的摘要.

If you execute ulimit -a it should provide a summary of all the current limits for child processes.

正如@bikram990 在下面的评论中提到的，java 进程可能不会遵守软限制.要强制执行 Java 内存限制，您可以向进程传递参数(-Xmx、-Xss 等...).

As mentioned in comments below by @bikram990, the java process may not observe soft limits. To enforce java memory restrictions, you can pass arguments to the process (-Xmx, -Xss, etc...).

警告！

您还可以通过 ulimit -H 命令设置硬限制，不能被子进程修改.但是，如果没有提升的权限(root)，这些限制也不能在降低后再次提高.

You can also set hard limits via the ulimit -H command, which cannot be modified by sub-processes. However, those limits also cannot be raised again once lowered, without elevated permissions (root).

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