Redis源码分析:内存管理
2016-06-02 13:12
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源码版本:redis 2.4.4
redis内存相关函数都放在zmalloc.h zmalloc.c中
redis中可以使用tcmalloc、jemalloc
Makefile:
[cpp] view
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ifeq ($(USE_TCMALLOC),yes)
ALLOC_DEP=
ALLOC_LINK=-ltcmalloc
ALLOC_FLAGS=-DUSE_TCMALLOC
endif
ifeq ($(USE_JEMALLOC),yes)
ALLOC_DEP=../deps/jemalloc/lib/libjemalloc.a
ALLOC_LINK=$(ALLOC_DEP) -ldl
ALLOC_FLAGS=-DUSE_JEMALLOC -I../deps/jemalloc/include
endif
zmalloc.c中
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#if defined(USE_TCMALLOC)
#define malloc(size) tc_malloc(size)
#define calloc(count,size) tc_calloc(count,size)
#define realloc(ptr,size) tc_realloc(ptr,size)
#define free(ptr) tc_free(ptr)
#elif defined(USE_JEMALLOC)
#define malloc(size) je_malloc(size)
#define calloc(count,size) je_calloc(count,size)
#define realloc(ptr,size) je_realloc(ptr,size)
#define free(ptr) je_free(ptr)
#endif
简单封装
void *zmalloc(size_t size);
void *zcalloc(size_t size);
void *zrealloc(void *ptr, size_t size);
void zfree(void *ptr);
分别对malloc、calloc、realloc、free做了简单封装
对zmalloc和zfree做分析
[cpp] view
plain copy
void *zmalloc(size_t size) {
void *ptr = malloc(size+PREFIX_SIZE);
if (!ptr) zmalloc_oom(size);
#ifdef HAVE_MALLOC_SIZE
update_zmalloc_stat_alloc(zmalloc_size(ptr),size);
return ptr;
#else
*((size_t*)ptr) = size;
update_zmalloc_stat_alloc(size+PREFIX_SIZE,size);
return (char*)ptr+PREFIX_SIZE;
#endif
}
void zfree(void *ptr) {
#ifndef HAVE_MALLOC_SIZE
void *realptr;
size_t oldsize;
#endif
if (ptr == NULL) return;
#ifdef HAVE_MALLOC_SIZE
update_zmalloc_stat_free(zmalloc_size(ptr));
free(ptr);
#else
realptr = (char*)ptr-PREFIX_SIZE;
oldsize = *((size_t*)realptr);
update_zmalloc_stat_free(oldsize+PREFIX_SIZE);
free(realptr);
#endif
}
除了分配给指定大小的内存之外,还分配了PREFIX_SIZE
内存格局如下:
申请内存返回Real_ptr
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#define update_zmalloc_stat_alloc(__n,__size) do { \
size_t _n = (__n); \
if (_n&(sizeof(long)-1)) _n += sizeof(long)-(_n&(sizeof(long)-1)); \
if (zmalloc_thread_safe) { \
pthread_mutex_lock(&used_memory_mutex); \
used_memory += _n; \
pthread_mutex_unlock(&used_memory_mutex); \
} else { \
used_memory += _n; \
} \
} while(0)
#define update_zmalloc_stat_free(__n) do { \
size_t _n = (__n); \
if (_n&(sizeof(long)-1)) _n += sizeof(long)-(_n&(sizeof(long)-1)); \
if (zmalloc_thread_safe) { \
pthread_mutex_lock(&used_memory_mutex); \
used_memory -= _n; \
pthread_mutex_unlock(&used_memory_mutex); \
} else { \
used_memory -= _n; \
} \
} while(0)
used_memory记录当前分配的总内存
在定义了 int vm_max_threads; /* Max number of I/O threads running at the same time */
if (server.vm_max_threads != 0)
zmalloc_enable_thread_safeness(); /* we need thread safe zmalloc() */
在使用Threaded Virtual Memory I/O的时候,需要安全的zmalloc
[cpp] view
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size_t zmalloc_used_memory(void) {
size_t um;
if (zmalloc_thread_safe) pthread_mutex_lock(&used_memory_mutex);
um = used_memory;
if (zmalloc_thread_safe) pthread_mutex_unlock(&used_memory_mutex);
return um;
}
zmalloc_used_memory返回进程当前使用的内存,用以做相应的清内存操作,eg:
[cpp] view
plain copy
zmalloc_used_memory() > server.maxmemory //和配置的最大内存比较
....
zmalloc_get_rss()用来计算进程实际使用物理内存
redis内存相关函数都放在zmalloc.h zmalloc.c中
redis中可以使用tcmalloc、jemalloc
Makefile:
[cpp] view
plain copy
ifeq ($(USE_TCMALLOC),yes)
ALLOC_DEP=
ALLOC_LINK=-ltcmalloc
ALLOC_FLAGS=-DUSE_TCMALLOC
endif
ifeq ($(USE_JEMALLOC),yes)
ALLOC_DEP=../deps/jemalloc/lib/libjemalloc.a
ALLOC_LINK=$(ALLOC_DEP) -ldl
ALLOC_FLAGS=-DUSE_JEMALLOC -I../deps/jemalloc/include
endif
zmalloc.c中
[cpp] view
plain copy
#if defined(USE_TCMALLOC)
#define malloc(size) tc_malloc(size)
#define calloc(count,size) tc_calloc(count,size)
#define realloc(ptr,size) tc_realloc(ptr,size)
#define free(ptr) tc_free(ptr)
#elif defined(USE_JEMALLOC)
#define malloc(size) je_malloc(size)
#define calloc(count,size) je_calloc(count,size)
#define realloc(ptr,size) je_realloc(ptr,size)
#define free(ptr) je_free(ptr)
#endif
简单封装
void *zmalloc(size_t size);
void *zcalloc(size_t size);
void *zrealloc(void *ptr, size_t size);
void zfree(void *ptr);
分别对malloc、calloc、realloc、free做了简单封装
对zmalloc和zfree做分析
[cpp] view
plain copy
void *zmalloc(size_t size) {
void *ptr = malloc(size+PREFIX_SIZE);
if (!ptr) zmalloc_oom(size);
#ifdef HAVE_MALLOC_SIZE
update_zmalloc_stat_alloc(zmalloc_size(ptr),size);
return ptr;
#else
*((size_t*)ptr) = size;
update_zmalloc_stat_alloc(size+PREFIX_SIZE,size);
return (char*)ptr+PREFIX_SIZE;
#endif
}
void zfree(void *ptr) {
#ifndef HAVE_MALLOC_SIZE
void *realptr;
size_t oldsize;
#endif
if (ptr == NULL) return;
#ifdef HAVE_MALLOC_SIZE
update_zmalloc_stat_free(zmalloc_size(ptr));
free(ptr);
#else
realptr = (char*)ptr-PREFIX_SIZE;
oldsize = *((size_t*)realptr);
update_zmalloc_stat_free(oldsize+PREFIX_SIZE);
free(realptr);
#endif
}
除了分配给指定大小的内存之外,还分配了PREFIX_SIZE
内存格局如下:
申请内存返回Real_ptr
[cpp] view
plain copy
#define update_zmalloc_stat_alloc(__n,__size) do { \
size_t _n = (__n); \
if (_n&(sizeof(long)-1)) _n += sizeof(long)-(_n&(sizeof(long)-1)); \
if (zmalloc_thread_safe) { \
pthread_mutex_lock(&used_memory_mutex); \
used_memory += _n; \
pthread_mutex_unlock(&used_memory_mutex); \
} else { \
used_memory += _n; \
} \
} while(0)
#define update_zmalloc_stat_free(__n) do { \
size_t _n = (__n); \
if (_n&(sizeof(long)-1)) _n += sizeof(long)-(_n&(sizeof(long)-1)); \
if (zmalloc_thread_safe) { \
pthread_mutex_lock(&used_memory_mutex); \
used_memory -= _n; \
pthread_mutex_unlock(&used_memory_mutex); \
} else { \
used_memory -= _n; \
} \
} while(0)
used_memory记录当前分配的总内存
在定义了 int vm_max_threads; /* Max number of I/O threads running at the same time */
if (server.vm_max_threads != 0)
zmalloc_enable_thread_safeness(); /* we need thread safe zmalloc() */
在使用Threaded Virtual Memory I/O的时候,需要安全的zmalloc
[cpp] view
plain copy
size_t zmalloc_used_memory(void) {
size_t um;
if (zmalloc_thread_safe) pthread_mutex_lock(&used_memory_mutex);
um = used_memory;
if (zmalloc_thread_safe) pthread_mutex_unlock(&used_memory_mutex);
return um;
}
zmalloc_used_memory返回进程当前使用的内存,用以做相应的清内存操作,eg:
[cpp] view
plain copy
zmalloc_used_memory() > server.maxmemory //和配置的最大内存比较
....
zmalloc_get_rss()用来计算进程实际使用物理内存
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