Nginx 메모리 관리

WBOY
풀어 주다: 2016-07-30 13:31:32
원래의
1283명이 탐색했습니다.

1. 소스 코드 위치

헤더 파일: http://trac.nginx.org/nginx/browser/nginx/src/core/ngx_palloc.h

소스 파일: http://trac.nginx.org/nginx/browser/nginx/src/core/ngx_palloc.c

2. 데이터 구조 정의

먼저 nginx 메모리 풀에 대해 알아보겠습니다. 주요 데이터 구조:

ngx_pool_data_t(메모리 풀 데이터 블록 구조)

<span> 1:</span><span>typedef</span> <span>struct</span> {<precourier new width:950px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 2:</span>     u_char               *last;        <precourier new width:950px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 3:</span>     u_char               *end;<precourier new width:950px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 4:</span>     ngx_pool_t           *next;<precourier new width:950px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 5:</span>     ngx_uint_t            failed;<precourier new width:950px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 6:</span> } ngx_pool_data_t; <ul> <li>last : 현재 메모리 풀에서 할당한 마지막 주소를 저장하는 unsigned char 형 포인터, 즉 여기부터 다음 할당이 시작된다. </li> <li>end: 메모리 풀의 끝 위치; </li> <li>next: 메모리 풀에는 많은 메모리 블록이 있으며 이 메모리 블록은 이 포인터를 통해 연결 목록으로 연결됩니다. 다음 메모리 블록을 가리킨다. </li> <li>failed: 메모리 풀 할당 실패 횟수입니다. </li> </ul><blockquote><p>ngx_pool_s(메모리 풀 헤더 구조) </p></blockquote><divcourier new width:950px color:black padding:0px direction:ltr line-height:12pt background-color:rgb><precourier new width:950px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 1:</span><span>struct</span> ngx_pool_s {<precourier new width:950px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 2:</span>     ngx_pool_data_t       d;<precourier new width:950px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 3:</span>     size_t                max;<precourier new width:950px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 4:</span>     ngx_pool_t           *current;<precourier new width:950px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 5:</span>     ngx_chain_t          *chain;<precourier new width:950px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 6:</span>     ngx_pool_large_t     *large;<precourier new width:950px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 7:</span>     ngx_pool_cleanup_t   *cleanup; <precourier new width:950px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 8:</span>     ngx_log_t            *log;<precourier new width:950px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 9:</span> };<ul> <li>d: 메모리 풀의 데이터 블록 </li> <li>max: 메모리 풀 데이터 블록의 최대값 </li> <li>current: 현재 메모리 풀을 가리킵니다. </li> <li>체인: 이 포인터는 ngx_chain_t 구조에 연결됩니다. </li> <li>대형: 할당된 공간이 최대값을 초과할 때 사용됩니다. ></li>cleanup: 메모리 풀 콜백 해제<li>log: 로그 정보<li> </ul>ngx_pool_data_t와 ngx_pool_t로 구성된 nginx 메모리 풀 구조는 아래와 같습니다. <p></p><p><img src="http://image.codes51.com/Article/image/20150814/20150814194335_5243.jpg" style="max-width:90%" style="max-width:90%" alt="Nginx 메모리 관리" ></p>3. 관련 기능 소개 <p></p><blockquote>메모리 풀 방식을 분석하기 전에 몇 가지 주요 메모리 관련 기능을 소개해야 합니다. <p></p> ngx_alloc: (malloc만 사용 단순 캡슐화)<p></p> <p><divcourier new width:870px color:black padding:0px direction:ltr line-height:12pt background-color:rgb><precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 1:</span><span>void</span> *<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 2:</span> ngx_alloc(size_t size, ngx_log_t *log)<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 3:</span> {<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 4:</span>     <span>void</span>  *p;<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 5:</span>  <precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 6:</span>     p = malloc(size);<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 7:</span>     <span>if</span> (p == NULL) {<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 8:</span>         ngx_log_error(NGX_LOG_EMERG, log, ngx_errno,<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 9:</span>                       <span>"malloc(%uz) failed"</span>, size);<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 10:</span>     }<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 11:</span>  <precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 12:</span>     ngx_log_debug2(NGX_LOG_DEBUG_ALLOC, log, 0, <span>"malloc: %p:%uz"</span>, p, size);<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 13:</span>  <precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 14:</span>     <span>return</span> p;<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 15:</span> }</precourier></precourier></precourier></precourier></precourier></precourier></precourier></precourier></precourier></precourier></precourier></precourier></precourier></precourier></precourier></divcourier></p> </blockquote><blockquote>ngx_calloc: (malloc을 호출하고 0으로 초기화) <p></p> </blockquote><blockquote><p><divcourier new width:870px color:black padding:0px direction:ltr line-height:12pt background-color:rgb><precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 1:</span><span>void</span> *<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 2:</span> ngx_calloc(size_t size, ngx_log_t *log)<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 3:</span> {<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 4:</span>     <span>void</span>  *p;<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 5:</span>  <precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 6:</span>     p = ngx_alloc(size, log);<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 7:</span>  <precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 8:</span>     <span>if</span> (p) {<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 9:</span>         ngx_memzero(p, size);<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 10:</span>     }<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 11:</span>  <precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 12:</span>     <span>return</span> p;<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 13:</span> }</precourier></precourier></precourier></precourier></precourier></precourier></precourier></precourier></precourier></precourier></precourier></precourier></precourier></divcourier></p></blockquote><blockquote>ngx_memzero: <p></p> <p><divcourier new width:870px color:black padding:0px direction:ltr line-height:12pt background-color:rgb><precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 1:</span> #define ngx_memzero(buf, n)       (<span>void</span>) memset(buf, 0, n)</precourier></divcourier></p> </blockquote><blockquote>ngx_free: <p></p> <p><divcourier new width:870px color:black padding:0px direction:ltr line-height:12pt background-color:rgb><precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 1:</span> #define ngx_free          free</precourier></divcourier></p> </blockquote><blockquote>ngx_memalign: <p></p> <p><divcourier new width:870px color:black padding:0px direction:ltr line-height:12pt background-color:rgb><precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 1:</span><span>void</span> *<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 2:</span> ngx_memalign(size_t alignment, size_t size, ngx_log_t *log)<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 3:</span> {<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 4:</span>     <span>void</span>  *p;<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 5:</span>     <span>int</span>    err;<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 6:</span>  <precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 7:</span>     err = posix_memalign(&p, alignment, size);<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 8:</span>  <precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 9:</span>     <span>if</span> (err) {<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 10:</span>         ngx_log_error(NGX_LOG_EMERG, log, err,<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 11:</span>                       <span>"posix_memalign(%uz, %uz) failed"</span>, alignment, size);<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 12:</span>         p = NULL;<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 13:</span>     }<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 14:</span>  <precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 15:</span>     ngx_log_debug3(NGX_LOG_DEBUG_ALLOC, log, 0,<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 16:</span>                    <span>"posix_memalign: %p:%uz @%uz"</span>, p, size, alignment);<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 17:</span>  <precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 18:</span>     <span>return</span> p;<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 19:</span> }</precourier></precourier></precourier></precourier></precourier></precourier></precourier></precourier></precourier></precourier></precourier></precourier></precourier></precourier></precourier></precourier></precourier></precourier></precourier></divcourier></p> </blockquote><limicrosoft yahei font-size:15px line-height:35px>여기서 정렬에 대한 가장 중요한 점은 동적 정렬이 필요한 일부 Unix 플랫폼의 경우 POSIX 1003.1d에서 제공하는 posix_memalign()이 캡슐화되어 있다는 것입니다. 대부분의 경우 컴파일러와 C 라이브러리는 정렬 문제를 투명하게 처리하도록 도와줍니다. nginx는 NGX_HAVE_POSIX_MEMALIGN 매크로에 의해 제어됩니다. <blockquote>posix_memalign( )<em>을 성공적으로 호출하면 </em>size<em>바이트의 동적 메모리가 반환되며 이 메모리의 주소는 </em>alignment<em> 배수입니다. </em>alignment<em> 매개변수는 2의 거듭제곱 또는 </em>void<em> 포인터 크기의 배수여야 합니다. 반환된 메모리 블록의 주소는 </em>memptr<em>에 위치하며 함수 반환값은 </em>0<em>.</em> </blockquote> <limicrosoft yahei font-size:15px line-height:35px> <blockquote></blockquote> 4. 메모리 풀의 기본 동작<p></p> <ul><li>메모리 풀의 주요 외부 방법은 다음과 같습니다. </li></ul> <limicrosoft yahei font-size:15px line-height:35px><table cellspacing="0" cellpadding="2" border="1"><tbody> <tr> <td valign="top" width="118">创建内存池</td> <td valign="top" width="768">ngx_pool_t *  ngx_create_pool(size_t size, ngx_log_t *log);</td> </tr> <tr> <td valign="top" width="118">销毁内存池</td> <td valign="top" width="768">void ngx_destroy_pool(ngx_pool_t *pool);</td> </tr> <tr> <td valign="top" width="118">重置内存池</td> <td valign="top" width="768">void ngx_reset_pool(ngx_pool_t *pool);</td> </tr> <tr> <td valign="top" width="118">内存申请(对齐)</td> <td valign="top" width="768">void *  ngx_palloc(ngx_pool_t *pool, size_t size);</td> </tr> <tr> <td valign="top" width="118">内存申请(不对齐)</td> <td valign="top" width="768">void *  ngx_pnalloc(ngx_pool_t *pool, size_t size);</td> </tr> <tr> <td valign="top" width="118">内存清除</td> <td valign="top" width="768">ngx_int_t  ngx_pfree(ngx_pool_t *pool, void *p);</td> </tr> </tbody></table> <limicrosoft yahei font-size:15px line-height:35px><limicrosoft yahei font-size:15px line-height:35px><p>4.1 创建内存池ngx_create_pool</p> <blockquote><p>ngx_create_pool用于创建一个内存池,我们创建时,传入我们的需要的初始大小:</p></blockquote> <limicrosoft yahei font-size:15px line-height:35px><blockquote><p><divcourier new width:870px color:black padding:0px direction:ltr line-height:12pt background-color:rgb><precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 1:</span> ngx_pool_t *<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 2:</span> ngx_create_pool(size_t size, ngx_log_t *log)<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 3:</span> {<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 4:</span>     ngx_pool_t  *p;<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 5:</span>     <precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 6:</span>     <span>//以16(NGX_POOL_ALIGNMENT)字节对齐分配size内存</span><precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 7:</span>     p = ngx_memalign(NGX_POOL_ALIGNMENT, size, log);<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 8:</span>     <span>if</span> (p == NULL) {<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 9:</span>         <span>return</span> NULL;<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 10:</span>     }<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 11:</span>  <precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 12:</span>     <span>//初始状态:last指向ngx_pool_t结构体之后数据取起始位置</span><precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 13:</span>     p->d.last = (u_char *) p + <span>sizeof</span>(ngx_pool_t);<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 14:</span>     <span>//end指向分配的整个size大小的内存的末尾</span><precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 15:</span>     p->d.end = (u_char *) p + size;<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 16:</span>     <precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 17:</span>     p->d.next = NULL;<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 18:</span>     p->d.failed = 0;<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 19:</span>  <precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 20:</span>     size = size - <span>sizeof</span>(ngx_pool_t);<precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 21:</span>     <span>//#define NGX_MAX_ALLOC_FROM_POOL  (ngx_pagesize - 1),内存池最大不超过4095,x86中页的大小为4K</span><precourier new width:870px padding:0px direction:ltr margin:0em line-height:12pt background-color:rgb><span> 22:</span>     p->max = (size < NGX_MAX_ALLOC_FROM_POOL) ? size : NGX_MAX_ALLOC_FROM_POOL;
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<span> 23:</span>
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24: p->current = p; 25:     p->chain = NULL; 26:     p->large = NULL; 27:     p->cleanup = NULL; 28:     p->log = log; 29:  30:     return p; 31: }

nginx对内存的管理分为大内存与小内存,当某一个申请的内存大于某一个值时,就需要从大内存中分配空间,否则从小内存中分配空间。

nginx中的内存池是在创建的时候就设定好了大小,在以后分配小块内存的时候,如果内存不够,则是重新创建一块内存串到内存池中,而不是将原有的内存池进行扩张。当要分配大块内存是,则是在内存池外面再分配空间进行管理的,称为大块内存池。

 

4.2 内存申请 ngx_palloc

1:void * 2: ngx_palloc(ngx_pool_t *pool, size_t size) 3: { 4:     u_char      *m; 5:     ngx_pool_t  *p; 6:  7:     //如果申请的内存大小小于内存池的max值 8:     if (size <= pool->max) { 9:  10:         p = pool->current; 11:  12:         do { 13:             //对内存地址进行对齐处理 14:             m = ngx_align_ptr(p->d.last, NGX_ALIGNMENT); 15:  16:             //如果当前内存块够分配内存,则直接分配 17:             if ((size_t) (p->d.end - m) >= size) 18:             { 19:                 p->d.last = m + size; 20:  21:                 return m; 22:             } 23:             24:             //如果当前内存块有效容量不够分配,则移动到下一个内存块进行分配 25:             p = p->d.next; 26:  27:         } while (p); 28:  29:         //当前所有内存块都没有空闲了,开辟一块新的内存,如下2详细解释 30:         return ngx_palloc_block(pool, size); 31:     } 32:  33:     //分配大块内存 34:     return ngx_palloc_large(pool, size); 35: }

需要说明的几点:

1、ngx_align_ptr,这是一个用来内存地址取整的宏,非常精巧,一句话就搞定了。作用不言而喻,取整可以降低CPU读取内存的次数,提高性能。因为这里并没有真正意义调用malloc等函数申请内存,而是移动指针标记而已,所以内存对齐的活,C编译器帮不了你了,得自己动手。

1: #define ngx_align_ptr(p, a)                                                   \ 2:      (u_char *) (((uintptr_t) (p) + ((uintptr_t) a - 1)) & ~((uintptr_t) a - 1))

2、开辟一个新的内存块 ngx_palloc_block(ngx_pool_t *pool, size_t size)

这个函数是用来分配新的内存块,为pool内存池开辟一个新的内存块,并申请使用size大小的内存;

1:static void * 2: ngx_palloc_block(ngx_pool_t *pool, size_t size) 3: { 4:     u_char      *m; 5:     size_t       psize; 6:     ngx_pool_t  *p, *new; 7:  8:     //计算内存池第一个内存块的大小 9:     psize = (size_t) (pool->d.end - (u_char *) pool); 10:  11:     //分配和第一个内存块同样大小的内存块 12:     m = ngx_memalign(NGX_POOL_ALIGNMENT, psize, pool->log); 13:     if (m == NULL) { 14:         return NULL; 15:     } 16:  17:     new = (ngx_pool_t *) m; 18:  19:     //设置新内存块的end 20:     new->d.end = m + psize; 21:     new->d.next = NULL; 22:     new->d.failed = 0; 23:  24:     //将指针m移动到d后面的一个位置,作为起始位置 25:     m += sizeof(ngx_pool_data_t); 26:     //对m指针按4字节对齐处理 27:     m = ngx_align_ptr(m, NGX_ALIGNMENT); 28:     //设置新内存块的last,即申请使用size大小的内存 29:     new->d.last = m + size; 30:  31:     //这里的循环用来找最后一个链表节点,这里failed用来控制循环的长度,如果分配失败次数达到5次,就忽略,不需要每次都从头找起 32:     for (p = pool->current; p->d.next; p = p->d.next) { 33:         if (p->d.failed++ > 4) { 34:             pool->current = p->d.next; 35:         } 36:     } 37:  38:     p->d.next = new; 39:  40:     return m; 41: }

3、分配大块内存 ngx_palloc_large(ngx_pool_t *pool, size_t size)

在ngx_palloc中首先会判断申请的内存大小是否超过内存块的最大限值,如果超过,则直接调用ngx_palloc_large,进入大内存块的分配流程;

1:static void * 2: ngx_palloc_large(ngx_pool_t *pool, size_t size) 3: { 4:     void              *p; 5:     ngx_uint_t         n; 6:     ngx_pool_large_t  *large; 7:  8:     // 直接在系统堆中分配一块大小为size的空间 9:     p = ngx_alloc(size, pool->log); 10:     if (p == NULL) { 11:         return NULL; 12:     } 13:  14:     n = 0; 15:  16:     // 查找到一个空的large区,如果有,则将刚才分配的空间交由它管理  17:     for (large = pool->large; large; large = large->next) { 18:         if (large->alloc == NULL) { 19:             large->alloc = p; 20:             return p; 21:         } 22:         //为了提高效率, 如果在三次内没有找到空的large结构体,则创建一个 23:         if (n++ > 3) { 24:             break; 25:         } 26:     } 27:  28:  29:     large = ngx_palloc(pool, sizeof(ngx_pool_large_t)); 30:     if (large == NULL) { 31:         ngx_free(p); 32:         return NULL; 33:     } 34:     35:     //将large链接到内存池 36:     large->alloc = p; 37:     large->next = pool->large; 38:     pool->large = large; 39:  40:     return p; 41: }

整个内存池分配如下图:

Nginx 메모리 관리

  • 4.3 内存池重置 ngx_reset_pool

1:void 2: ngx_reset_pool(ngx_pool_t *pool) 3: { 4:     ngx_pool_t        *p; 5:     ngx_pool_large_t  *l; 6:     7:     //释放大块内存 8:     for (l = pool->large; l; l = l->next) { 9:         if (l->alloc) { 10:             ngx_free(l->alloc); 11:         } 12:     } 13:     14:     // 重置所有小块内存区 15:     for (p = pool; p; p = p->d.next) { 16:         p->d.last = (u_char *) p + sizeof(ngx_pool_t); 17:         p->d.failed = 0; 18:     } 19:  20:     pool->current = pool; 21:     pool->chain = NULL; 22:     pool->large = NULL; 23: }

4.4 内存池释放 ngx_pfree

1: ngx_int_t 2: ngx_pfree(ngx_pool_t *pool, void *p) 3: { 4:     ngx_pool_large_t  *l; 5:  6:     //只检查是否是大内存块,如果是大内存块则释放 7:     for (l = pool->large; l; l = l->next) { 8:         if (p == l->alloc) { 9:             ngx_log_debug1(NGX_LOG_DEBUG_ALLOC, pool->log, 0, 10:                            "free: %p", l->alloc); 11:             ngx_free(l->alloc); 12:             l->alloc = NULL; 13:  14:             return NGX_OK; 15:         } 16:     } 17: 

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