blocks|key|13134|text|进程结束时，由malloc()分配的内存将被释放。但是，使用shmget()分配的内存在进程结束时不会被释放。小心点。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|13135|编辑：|13136|mmap()不是shmget()阅读这里的区别：http://www.opengroup.org/onlinepubs/000095399/functions/mmap.html+http://www.opengroup.org/onlinepubs/009695399/functions/shmget.html|13137|它们是不同的系统调用，它们做的是非常不同的事情。|13138|entityMap|0|LINK|mutability|MUTABLE|url|http://www.opengroup.org/onlinepubs/000095399/functions/mmap.html|1|http://www.opengroup.org/onlinepubs/009695399/functions/shmget.html^0|7|8|U|8|0|0|O|1T|0|2I|1V|1|0|0^^$0|@$1|2|3|4|5|6|7|V|8|@$9|W|A|X|B|C]|$9|Y|A|Z|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|10|8|@]|D|@]|E|$]]|$1|H|3|I|5|6|7|11|8|@]|D|@$9|12|A|13|1|14]|$9|15|A|16|1|17]]|E|$]]|$1|J|3|K|5|6|7|18|8|@]|D|@]|E|$]]|$1|L|3|-4|5|6|7|19|8|@]|D|@]|E|$]]]|M|$N|$5|O|P|Q|E|$R|S]]|T|$5|O|P|Q|E|$R|U]]]]

Memory allocated by <code>malloc()</code> is freed when the process ends. However memory allocated using <code>shmget()</code> is not freed when the process ends. Be careful with that.

Edit:

mmap() is not shmget() read about the difference here: <a href="http://www.opengroup.org/onlinepubs/000095399/functions/mmap.html" rel="nofollow noreferrer">http://www.opengroup.org/onlinepubs/000095399/functions/mmap.html</a> <a href="http://www.opengroup.org/onlinepubs/009695399/functions/shmget.html" rel="nofollow noreferrer">http://www.opengroup.org/onlinepubs/009695399/functions/shmget.html</a>

They are different system calls, which do very different things.

blocks|key|4117980|text|是的，当进程终止时，内存被释放。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4117981|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|$]]

Yes, the memory is freed when the process terminates.

blocks|key|899852|text|进程结束时肯定会释放malloc()ed内存，但不是通过调用free()。它是从MMU表中删除的整个内存映射(以线性RAM的形式呈现给进程)。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|899853|entityMap^0|A|8|U|6|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|M|8|@]|D|@]|E|$]]]|G|$]]

<code>malloc()</code>ed memory is definitely freed when the process ends, but not by calling <code>free()</code>. it's the whole memory mapping (presented to the process as linear RAM) that is just deleted from the MMU tables.

blocks|key|1316095|text|在Linux+(和大多数其他Unixes)中，当您从命令shell调用程序时，它会创建一个新进程来运行该程序。进程保留的所有资源，包括堆内存，都应该在进程终止时释放回操作系统。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1316096|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|$]]

In Linux (and most other Unixes) when you invoke a program from a command shell, it creates a new process to run that program in. All resources a process reserves, including heap memory, should get released back to the OS when your process terminates.

blocks|key|899884|text|内存“分配”有两个不同的含义，在这样的问题中通常是重叠的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|899885|899886|内存由sbrk系统调用提供给进程，|unordered-list-item|899887|内存由|899888|分配给程序上下文中的某些用途|899889|​|899890|sbrk系统调用告诉内核准备更多内存，以防进程需要。直到内存被写入之前，它才真正映射到进程地址空间中。这称为请求分页。通常，在进程退出之前，操作系统不会真正撤销访问此内存的权限。如果内存变得不足，那么kswapd+(内核的一部分)将把最少使用的部分转移到磁盘上以腾出空间。如果您愿意，内核可以对进程工作集中的内存量实施硬限制:)|899891|第二个上下文是您在调用malloc/free时所谈论的上下文。malloc保存可用内存列表，并在请求时将数据块分发给您的函数。如果它检测到手头没有足够的内存来满足请求，它将调用sbrk以允许进程访问更多内存。|899892|当您查看top的输出时，您将看到一个进程的内存使用情况的两个数字。对于‘虚拟大小’和‘驻留大小’，虚拟大小是进程请求访问的总量。驻留大小是进程当前正在使用的数量。|899893|899894|entityMap^0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|V|8|@]|9|@]|A|$]]|$1|C|3|D|5|E|7|W|8|@]|9|@]|A|$]]|$1|F|3|G|5|E|7|X|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|Y|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|Z|8|@]|9|@]|A|$]]|$1|L|3|M|5|6|7|10|8|@]|9|@]|A|$]]|$1|N|3|O|5|6|7|11|8|@]|9|@]|A|$]]|$1|P|3|Q|5|6|7|12|8|@]|9|@]|A|$]]|$1|R|3|K|5|6|7|13|8|@]|9|@]|A|$]]|$1|S|3|-4|5|6|7|14|8|@]|9|@]|A|$]]]|T|$]]

Memory 'allocation' has two distinct meanings that are commonly overlapped in questions like this.

<ul>
<li> memory is made available to the process by the sbrk system call</li>
<li> memory is assigned to some purpose within the context of the program by malloc() </li>
</ul>


the sbrk system call tell the kernel to get some more memory ready in case the process needs it. the memory is not actually mapped into the processes address space until immediately before it is written to. This is called demand paging. Typically the right to access this memory is never actually revoked by the operating system until the process exits. If memory becomes scarce then the kswapd (part of the kernel) will shuffle the least used parts off to disk to make room. The kernel can enforce a hard limit on the ammount of memory in a processes working set if you would like :)

the second context is what you are talking about when you call malloc/free. malloc keeps a list of available memory and hands chunks out to your functions when requested. if it detects that it doesnt have enough memory on hand to meet a request it will call sbrk to allow the process to access more. 

when you look at the output of top you will see two numbers for a processes memory usage. One for the 'virtual size' and 'resident size', virtual size is the total amount that the process has requested access to. resident size is the amount that is actively being used by the process at the moment.

blocks|key|1316075|text|当程序退出时，内存从程序点释放。在此之后，它不会以任何方式捆绑在一起，并且可以被其他进程重用。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1316076|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|$]]

The memory is released from the point of the program when it exits. It is not tied up in any way after that and can be reused by other processes.

blocks|key|13278|text|现代操作系统会在进程终止时释放该进程分配的所有内存。唯一可能不是这样的情况可能是在非常旧的操作系统中(也许是DOS?)还有一些嵌入式系统。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|13279|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|$]]

modern operating systems will release all memory allocated by a process when that process is terminated. The only situations where that might not be true, would probably be in very old operating systems (perhaps DOS?) and some embedded systems.

If you do not free memory that you malloc'd in a C program under Linux, when is it released? After the program terminates? Or is the memory still locked up until an unforseen time (probably at reboot)?

Freeing memory in C under Linux

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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如果你没有释放你在Linux下的C程序中被恶意锁定的内存，它什么时候释放？在程序终止后？或者内存仍然被锁定，直到不可预知的时间(可能是在重启时)？

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