jemalloc

jemalloc是一个内存分配实现库。主要提供malloc, calloc, realloc, free这几个函数实现。这几个函数都是C标准函数，在标准库中都有实现，如glibc, VC等都提供了C标准库的实现，其中都有这几个函数的实现。jemalloc是非标准库提供的实现，类似的还有tcmalloc等。glibc中的实现实际上就是ptmalloc。

 

jemalloc安装

# autoconf

# mkdir obj

# cd obj

# ../configure --prefix=/usr/local/jemalloc-1.0.0

# make

# make install

 

写道

.
├── bin
│   └── pprof
├── include
│   └── jemalloc
│   ├── jemalloc_defs.h
│   └── jemalloc.h
├── lib
│   ├── libjemalloc_pic.a
│   ├── libjemalloc.so -> libjemalloc.so.0
│   └── libjemalloc.so.0
└── share
└── man
└── man3
└── jemalloc.3

7 directories, 7 files

jemalloc安装后，只有两个头文件：jemalloc.h，jemalloc_defs.h。我们只会用到jemalloc.h。

 

默认情况下安装

支持小块内存

#define JEMALLOC_TINY 

 

支持线程缓存层

#define JEMALLOC_TCACHE

 

支持延迟锁定

#define JEMALLOC_LAZY_LOCK

 

# ../configure --enable-debug --prefix=/usr/local/jemalloc-1.0.0

# ../configure --enable-prof --prefix=/usr/local/jemalloc-1.0.0

 

运行时配置

运行时配置包括/etc/jemalloc.conf配置文件，环境变量

/etc/jemalloc.conf

 

环境变量

JEMALLOC_OPTIONS

 

 

#include <stdio.h>
#include <jemalloc.h>

int main()
{
  char *ptr = (char *) malloc(111);
  printf("ptr@%p\n", ptr);
  return 0;
}

编译

 

# gcc -I/usr/local/jemalloc-1.0.0/include/jemalloc -L/usr/local/jemalloc-1.0.0/lib malloc_test.c -o malloc_test -ljemalloc

运行

# ./malloc_test 

./malloc_test: error while loading shared libraries: libjemalloc.so.0: cannot open shared object file: No such file or directory

这里报没找到libjemalloc.so.0错误

# ldd malloc_test

linux-gate.so.1 =>  (0x00670000)

libjemalloc.so.0 => not found

libc.so.6 => /lib/libc.so.6 (0x00ae3000)

 

/lib/ld-linux.so.2 (0x80039000)

 

通过-Wl指定连接选项--rpath：

# gcc -Wl,--rpath=/usr/local/jemalloc-1.0.0/lib -I/usr/local/jemalloc-1.0.0/include/jemalloc -L/usr/local/jemalloc-1.0.0/lib malloc_test.c -o malloc_test -ljemalloc

# ./malloc_test 

ptr@0xb6804040

 

 

 

jemalloc源代码分析

 

jemalloc源代码并没有直接提供configure或者Makefile来配置，构建和安装。jemalloc提供了autogen.sh工具用来配置并生成Makefile。不过这种方式无法指定自定义安装目录，默认安装在/usr/local，/usr/local/bin，/usr/local/include，/usr/local/lib，/usr/local/share，/usr/local/share/man下。

 

可以通过autoconf来生成configure配置。这样我们可以通过configure指定自定义安装目录。

 

 

 

jemalloc.h.in，jemalloc_defs.h.in

 

/* include/jemalloc/jemalloc_defs.h.  Generated from jemalloc_defs.h.in by configure.  */
#ifndef JEMALLOC_DEFS_H_
#define	JEMALLOC_DEFS_H_

/*
 * If JEMALLOC_PREFIX is defined, it will cause all public APIs to be prefixed.
 * This makes it possible, with some care, to use multiple allocators
 * simultaneously.
 *
 * In many cases it is more convenient to manually prefix allocator function
 * calls than to let macros do it automatically, particularly when using
 * multiple allocators simultaneously.  Define JEMALLOC_MANGLE before
 * #include'ing jemalloc.h in order to cause name mangling that corresponds to
 * the API prefixing.
 */
/* #undef JEMALLOC_PREFIX */
#if (defined(JEMALLOC_PREFIX) && defined(JEMALLOC_MANGLE))
/* #undef JEMALLOC_P */
#endif

/*
 * Hyper-threaded CPUs may need a special instruction inside spin loops in
 * order to yield to another virtual CPU.
 */
#define CPU_SPINWAIT __asm__ volatile("pause")

/* Defined if __attribute__((...)) syntax is supported. */
#define JEMALLOC_HAVE_ATTR 
#ifdef JEMALLOC_HAVE_ATTR
#  define JEMALLOC_ATTR(s) __attribute__((s))
#else
#  define JEMALLOC_ATTR(s)
#endif

/*
 * JEMALLOC_DEBUG enables assertions and other sanity checks, and disables
 * inline functions.
 */
/* #undef JEMALLOC_DEBUG */

/* JEMALLOC_STATS enables statistics calculation. */
/* #undef JEMALLOC_STATS */

/* JEMALLOC_PROF enables allocation profiling. */
/* #undef JEMALLOC_PROF */

/* Use libunwind for profile backtracing if defined. */
/* #undef JEMALLOC_PROF_LIBUNWIND */

/* Use libgcc for profile backtracing if defined. */
/* #undef JEMALLOC_PROF_LIBGCC */

/*
 * JEMALLOC_TINY enables support for tiny objects, which are smaller than one
 * quantum.
 */
#define JEMALLOC_TINY 

/*
 * JEMALLOC_TCACHE enables a thread-specific caching layer for small objects.
 * This makes it possible to allocate/deallocate objects without any locking
 * when the cache is in the steady state.
 */
#define JEMALLOC_TCACHE 

/*
 * JEMALLOC_DSS enables use of sbrk(2) to allocate chunks from the data storage
 * segment (DSS).
 */
/* #undef JEMALLOC_DSS */

/* JEMALLOC_SWAP enables mmap()ed swap file support. */
/* #undef JEMALLOC_SWAP */

/* Support memory filling (junk/zero). */
/* #undef JEMALLOC_FILL */

/* Support optional abort() on OOM. */
/* #undef JEMALLOC_XMALLOC */

/* Support SYSV semantics. */
/* #undef JEMALLOC_SYSV */

/* Support lazy locking (avoid locking unless a second thread is launched). */
#define JEMALLOC_LAZY_LOCK 

/* Determine page size at run time if defined. */
/* #undef DYNAMIC_PAGE_SHIFT */

/* One page is 2^STATIC_PAGE_SHIFT bytes. */
#define STATIC_PAGE_SHIFT 12

/* TLS is used to map arenas and magazine caches to threads. */
/* #undef NO_TLS */

/* sizeof(void *) == 2^LG_SIZEOF_PTR. */
#define LG_SIZEOF_PTR 2

/* sizeof(int) == 2^LG_SIZEOF_INT. */
#define LG_SIZEOF_INT 2

#endif /* JEMALLOC_DEFS_H_ */

 

分配区

arena_t**arenas;

 

unsignednarenas;

arenas是一个arena_t类型的双指针，表示一组分配区，arenas中的每个元素都是一个arena_t类型的指针，它指向一个分配区。

narenas表示分配区数。

 

 

分配内存

 

malloc

 

JEMALLOC_ATTR(malloc)
JEMALLOC_ATTR(visibility("default"))
void *
JEMALLOC_P(malloc)(size_t size)
{
	void *ret;
#ifdef JEMALLOC_PROF
	prof_thr_cnt_t *cnt;
#endif

	if (malloc_init()) {
		ret = NULL;
		goto OOM;
	}

	if (size == 0) {
#ifdef JEMALLOC_SYSV
		if (opt_sysv == false)
#endif
			size = 1;
#ifdef JEMALLOC_SYSV
		else {
#  ifdef JEMALLOC_XMALLOC
			if (opt_xmalloc) {
				malloc_write("<jemalloc>: Error in malloc(): "
				    "invalid size 0\n");
				abort();
			}
#  endif
			ret = NULL;
			goto RETURN;
		}
#endif
	}

#ifdef JEMALLOC_PROF
	if (opt_prof) {
		if ((cnt = prof_alloc_prep(size)) == NULL) {
			ret = NULL;
			goto OOM;
		}
		if (prof_promote && (uintptr_t)cnt != (uintptr_t)1U && size <=
		    small_maxclass) {
			ret = imalloc(small_maxclass+1);
			if (ret != NULL)
				arena_prof_promoted(ret, size);
		} else
			ret = imalloc(size);
	} else
#endif
		ret = imalloc(size);

OOM:
	if (ret == NULL) {
#ifdef JEMALLOC_XMALLOC
		if (opt_xmalloc) {
			malloc_write("<jemalloc>: Error in malloc(): "
			    "out of memory\n");
			abort();
		}
#endif
		errno = ENOMEM;
	}

#ifdef JEMALLOC_SYSV
RETURN:
#endif
#ifdef JEMALLOC_PROF
	if (opt_prof && ret != NULL)
		prof_malloc(ret, cnt);
#endif
	return (ret);
}

函数malloc主要调用了两个函数，malloc_init和imalloc。

 

malloc_init

static inline bool
malloc_init(void)
{

	if (malloc_initialized == false)
		return (malloc_init_hard());

	return (false);
}

malloc_init函数初始化成功返回false, 失败返回true。这个返回有点奇怪，不过比较符合linux风格，false表示0，true表示1，这在linux中，函数调用成功的话返回0，返回非0通常表示函数调用失败。

 

malloc_init函数很简单，首先判断是否已经初始化，malloc_initialized初始化为false, 如果还没有初始化，调用malloc_init_hard初始化，初始化后malloc_initialized为true。

 

malloc_init_hard

static bool
malloc_init_hard(void)
{
	unsigned i;
	int linklen;
	char buf[PATH_MAX + 1];
	const char *opts;
	arena_t *init_arenas[1];

	malloc_mutex_lock(&init_lock);
	if (malloc_initialized || malloc_initializer == pthread_self()) {
		/*
		 * Another thread initialized the allocator before this one
		 * acquired init_lock, or this thread is the initializing
		 * thread, and it is recursively allocating.
		 */
		malloc_mutex_unlock(&init_lock);
		return (false);
	}
	if (malloc_initializer != (unsigned long)0) {
		/* Busy-wait until the initializing thread completes. */
		do {
			malloc_mutex_unlock(&init_lock);
			CPU_SPINWAIT;
			malloc_mutex_lock(&init_lock);
		} while (malloc_initialized == false);
		return (false);
	}

#ifdef DYNAMIC_PAGE_SHIFT
	/* Get page size. */
	{
		long result;

		result = sysconf(_SC_PAGESIZE);
		assert(result != -1);
		pagesize = (unsigned)result;

		/*
		 * We assume that pagesize is a power of 2 when calculating
		 * pagesize_mask and lg_pagesize.
		 */
		assert(((result - 1) & result) == 0);
		pagesize_mask = result - 1;
		lg_pagesize = ffs((int)result) - 1;
	}
#endif

	for (i = 0; i < 3; i++) {
		unsigned j;

		/* Get runtime configuration. */
		switch (i) {
		case 0:
			if ((linklen = readlink("/etc/jemalloc.conf", buf,
						sizeof(buf) - 1)) != -1) {
				/*
				 * Use the contents of the "/etc/jemalloc.conf"
				 * symbolic link's name.
				 */
				buf[linklen] = '\0';
				opts = buf;
			} else {
				/* No configuration specified. */
				buf[0] = '\0';
				opts = buf;
			}
			break;
		case 1:
			if ((opts = getenv("JEMALLOC_OPTIONS")) != NULL) {
				/*
				 * Do nothing; opts is already initialized to
				 * the value of the JEMALLOC_OPTIONS
				 * environment variable.
				 */
			} else {
				/* No configuration specified. */
				buf[0] = '\0';
				opts = buf;
			}
			break;
		case 2:
			if (JEMALLOC_P(malloc_options) != NULL) {
				/*
				 * Use options that were compiled into the
				 * program.
				 */
				opts = JEMALLOC_P(malloc_options);
			} else {
				/* No configuration specified. */
				buf[0] = '\0';
				opts = buf;
			}
			break;
		default:
			/* NOTREACHED */
			assert(false);
			buf[0] = '\0';
			opts = buf;
		}

		for (j = 0; opts[j] != '\0'; j++) {
			unsigned k, nreps;
			bool nseen;

			/* Parse repetition count, if any. */
			for (nreps = 0, nseen = false;; j++, nseen = true) {
				switch (opts[j]) {
					case '0': case '1': case '2': case '3':
					case '4': case '5': case '6': case '7':
					case '8': case '9':
						nreps *= 10;
						nreps += opts[j] - '0';
						break;
					default:
						goto MALLOC_OUT;
				}
			}
MALLOC_OUT:
			if (nseen == false)
				nreps = 1;

			for (k = 0; k < nreps; k++) {
				switch (opts[j]) {
				case 'a':
					opt_abort = false;
					break;
				case 'A':
					opt_abort = true;
					break;
#ifdef JEMALLOC_PROF
				case 'b':
					if (opt_lg_prof_bt_max > 0)
						opt_lg_prof_bt_max--;
					break;
				case 'B':
					if (opt_lg_prof_bt_max < LG_PROF_BT_MAX)
						opt_lg_prof_bt_max++;
					break;
#endif
				case 'c':
					if (opt_lg_cspace_max - 1 >
					    opt_lg_qspace_max &&
					    opt_lg_cspace_max >
					    LG_CACHELINE)
						opt_lg_cspace_max--;
					break;
				case 'C':
					if (opt_lg_cspace_max < PAGE_SHIFT
					    - 1)
						opt_lg_cspace_max++;
					break;
				case 'd':
					if (opt_lg_dirty_mult + 1 <
					    (sizeof(size_t) << 3))
						opt_lg_dirty_mult++;
					break;
				case 'D':
					if (opt_lg_dirty_mult >= 0)
						opt_lg_dirty_mult--;
					break;
#ifdef JEMALLOC_PROF
				case 'e':
					opt_prof_active = false;
					break;
				case 'E':
					opt_prof_active = true;
					break;
				case 'f':
					opt_prof = false;
					break;
				case 'F':
					opt_prof = true;
					break;
#endif
#ifdef JEMALLOC_TCACHE
				case 'g':
					if (opt_lg_tcache_gc_sweep >= 0)
						opt_lg_tcache_gc_sweep--;
					break;
				case 'G':
					if (opt_lg_tcache_gc_sweep + 1 <
					    (sizeof(size_t) << 3))
						opt_lg_tcache_gc_sweep++;
					break;
				case 'h':
					opt_tcache = false;
					break;
				case 'H':
					opt_tcache = true;
					break;
#endif
#ifdef JEMALLOC_PROF
				case 'i':
					if (opt_lg_prof_interval >= 0)
						opt_lg_prof_interval--;
					break;
				case 'I':
					if (opt_lg_prof_interval + 1 <
					    (sizeof(uint64_t) << 3))
						opt_lg_prof_interval++;
					break;
#endif
#ifdef JEMALLOC_FILL
				case 'j':
					opt_junk = false;
					break;
				case 'J':
					opt_junk = true;
					break;
#endif
				case 'k':
					/*
					 * Chunks always require at least one
					 * header page, plus one data page.
					 */
					if ((1U << (opt_lg_chunk - 1)) >=
					    (2U << PAGE_SHIFT))
						opt_lg_chunk--;
					break;
				case 'K':
					if (opt_lg_chunk + 1 <
					    (sizeof(size_t) << 3))
						opt_lg_chunk++;
					break;
#ifdef JEMALLOC_PROF
				case 'l':
					opt_prof_leak = false;
					break;
				case 'L':
					opt_prof_leak = true;
					break;
#endif
#ifdef JEMALLOC_TCACHE
				case 'm':
					if (opt_lg_tcache_maxclass >= 0)
						opt_lg_tcache_maxclass--;
					break;
				case 'M':
					if (opt_lg_tcache_maxclass + 1 <
					    (sizeof(size_t) << 3))
						opt_lg_tcache_maxclass++;
					break;
#endif
				case 'n':
					opt_narenas_lshift--;
					break;
				case 'N':
					opt_narenas_lshift++;
					break;
#ifdef JEMALLOC_SWAP
				case 'o':
					opt_overcommit = false;
					break;
				case 'O':
					opt_overcommit = true;
					break;
#endif
				case 'p':
					opt_stats_print = false;
					break;
				case 'P':
					opt_stats_print = true;
					break;
				case 'q':
					if (opt_lg_qspace_max > LG_QUANTUM)
						opt_lg_qspace_max--;
					break;
				case 'Q':
					if (opt_lg_qspace_max + 1 <
					    opt_lg_cspace_max)
						opt_lg_qspace_max++;
					break;
#ifdef JEMALLOC_PROF
				case 's':
					if (opt_lg_prof_sample > 0)
						opt_lg_prof_sample--;
					break;
				case 'S':
					if (opt_lg_prof_sample + 1 <
					    (sizeof(uint64_t) << 3))
						opt_lg_prof_sample++;
					break;
				case 'u':
					opt_prof_udump = false;
					break;
				case 'U':
					opt_prof_udump = true;
					break;
#endif
#ifdef JEMALLOC_SYSV
				case 'v':
					opt_sysv = false;
					break;
				case 'V':
					opt_sysv = true;
					break;
#endif
#ifdef JEMALLOC_XMALLOC
				case 'x':
					opt_xmalloc = false;
					break;
				case 'X':
					opt_xmalloc = true;
					break;
#endif
#ifdef JEMALLOC_FILL
				case 'z':
					opt_zero = false;
					break;
				case 'Z':
					opt_zero = true;
					break;
#endif
				default: {
					char cbuf[2];

					cbuf[0] = opts[j];
					cbuf[1] = '\0';
					malloc_write(
					    "<jemalloc>: Unsupported character "
					    "in malloc options: '");
					malloc_write(cbuf);
					malloc_write("'\n");
				}
				}
			}
		}
	}

	/* Register fork handlers. */
	if (pthread_atfork(jemalloc_prefork, jemalloc_postfork,
	    jemalloc_postfork) != 0) {
		malloc_write("<jemalloc>: Error in pthread_atfork()\n");
		if (opt_abort)
			abort();
	}

	if (ctl_boot()) {
		malloc_mutex_unlock(&init_lock);
		return (true);
	}

	if (opt_stats_print) {
		/* Print statistics at exit. */
		if (atexit(stats_print_atexit) != 0) {
			malloc_write("<jemalloc>: Error in atexit()\n");
			if (opt_abort)
				abort();
		}
	}

	if (chunk_boot()) {
		malloc_mutex_unlock(&init_lock);
		return (true);
	}

	if (base_boot()) {
		malloc_mutex_unlock(&init_lock);
		return (true);
	}

#ifdef JEMALLOC_PROF
	prof_boot0();
#endif

	if (arena_boot()) {
		malloc_mutex_unlock(&init_lock);
		return (true);
	}

#ifdef JEMALLOC_TCACHE
	tcache_boot();
#endif

	if (huge_boot()) {
		malloc_mutex_unlock(&init_lock);
		return (true);
	}

	/*
	 * Create enough scaffolding to allow recursive allocation in
	 * malloc_ncpus().
	 */
	narenas = 1;
	arenas = init_arenas;
	memset(arenas, 0, sizeof(arena_t *) * narenas);

	/*
	 * Initialize one arena here.  The rest are lazily created in
	 * choose_arena_hard().
	 */
	arenas_extend(0);
	if (arenas[0] == NULL) {
		malloc_mutex_unlock(&init_lock);
		return (true);
	}

#ifndef NO_TLS
	/*
	 * Assign the initial arena to the initial thread, in order to avoid
	 * spurious creation of an extra arena if the application switches to
	 * threaded mode.
	 */
	arenas_map = arenas[0];
#endif

	malloc_mutex_init(&arenas_lock);

#ifdef JEMALLOC_PROF
	if (prof_boot1()) {
		malloc_mutex_unlock(&init_lock);
		return (true);
	}
#endif

	/* Get number of CPUs. */
	malloc_initializer = pthread_self();
	malloc_mutex_unlock(&init_lock);
	ncpus = malloc_ncpus();
	malloc_mutex_lock(&init_lock);

	if (ncpus > 1) {
		/*
		 * For SMP systems, create more than one arena per CPU by
		 * default.
		 */
		opt_narenas_lshift += 2;
	}

	/* Determine how many arenas to use. */
	narenas = ncpus;
	if (opt_narenas_lshift > 0) {
		if ((narenas << opt_narenas_lshift) > narenas)
			narenas <<= opt_narenas_lshift;
		/*
		 * Make sure not to exceed the limits of what base_alloc() can
		 * handle.
		 */
		if (narenas * sizeof(arena_t *) > chunksize)
			narenas = chunksize / sizeof(arena_t *);
	} else if (opt_narenas_lshift < 0) {
		if ((narenas >> -opt_narenas_lshift) < narenas)
			narenas >>= -opt_narenas_lshift;
		/* Make sure there is at least one arena. */
		if (narenas == 0)
			narenas = 1;
	}

#ifdef NO_TLS
	if (narenas > 1) {
		static const unsigned primes[] = {1, 3, 5, 7, 11, 13, 17, 19,
		    23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83,
		    89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149,
		    151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211,
		    223, 227, 229, 233, 239, 241, 251, 257, 263};
		unsigned nprimes, parenas;

		/*
		 * Pick a prime number of hash arenas that is more than narenas
		 * so that direct hashing of pthread_self() pointers tends to
		 * spread allocations evenly among the arenas.
		 */
		assert((narenas & 1) == 0); /* narenas must be even. */
		nprimes = (sizeof(primes) >> LG_SIZEOF_INT);
		parenas = primes[nprimes - 1]; /* In case not enough primes. */
		for (i = 1; i < nprimes; i++) {
			if (primes[i] > narenas) {
				parenas = primes[i];
				break;
			}
		}
		narenas = parenas;
	}
#endif

#ifndef NO_TLS
	next_arena = 0;
#endif

	/* Allocate and initialize arenas. */
	arenas = (arena_t **)base_alloc(sizeof(arena_t *) * narenas);
	if (arenas == NULL) {
		malloc_mutex_unlock(&init_lock);
		return (true);
	}
	/*
	 * Zero the array.  In practice, this should always be pre-zeroed,
	 * since it was just mmap()ed, but let's be sure.
	 */
	memset(arenas, 0, sizeof(arena_t *) * narenas);
	/* Copy the pointer to the one arena that was already initialized. */
	arenas[0] = init_arenas[0];

	malloc_initialized = true;
	malloc_mutex_unlock(&init_lock);
	return (false);
}

malloc_init_hard根据CPU数初始化arenas，arenas中的每个元素都是一个arena_t类型的指针，有多少个CPU，就分配多少个元素（arena_t类型的指针），但初始时，只会初始化一个arena（分配区）。

 

首先是获取运行时配置，根据这个配置，开始后面的初始化。为当前线程调用fork注册几个handle函数：jemalloc_prefork，jemalloc_postfork。调用ctl_boot初始化一个ctl互斥锁。调用chunk_boot，根据opt_lg_chunk设置chunk大小，chunk大小掩码，chunk页数，如果开启了stats或者prof，初始化一个chunks互斥锁，如果开启了swap，调用chunk_swap_boot，初始化一个swap互斥锁，并初始化swap，如果开启了dss，调用chunk_dss_boot，初始化一个dss互斥锁，并初始化dss。调用base_boot初始化一个base互斥锁。如果开启了prof，调用prof_boot0初始化prof。调用arena_boot，初始化arena。如果开启了tcache，调用tcache_boot，初始化tcache。调用huge_boot，初始化huge。初始化一个arena。如果开启了tls，将初始arena分配给初始线程。初始化一个arenas互斥锁。如果开启了prof，调用prof_boot1初始化prof。设置malloc_initializer为当前线程，并获取CPU数。

 

调用base_alloc分配和初始化arenas。

 

最后会将malloc_initialized设置为true，表示初始化好了。

 

imalloc

JEMALLOC_INLINE void *
imalloc(size_t size)
{

	assert(size != 0);

	if (size <= arena_maxclass)
		return (arena_malloc(size, false));
	else
		return (huge_malloc(size, false));
}

 

void *
arena_malloc(size_t size, bool zero)
{

	assert(size != 0);
	assert(QUANTUM_CEILING(size) <= arena_maxclass);

	if (size <= small_maxclass) {
#ifdef JEMALLOC_TCACHE
		tcache_t *tcache;

		if ((tcache = tcache_get()) != NULL)
			return (tcache_alloc_small(tcache, size, zero));
		else

#endif
			return (arena_malloc_small(choose_arena(), size, zero));
	} else {
#ifdef JEMALLOC_TCACHE
		if (size <= tcache_maxclass) {
			tcache_t *tcache;

			if ((tcache = tcache_get()) != NULL)
				return (tcache_alloc_large(tcache, size, zero));
			else {
				return (arena_malloc_large(choose_arena(),
				    size, zero));
			}
		} else
#endif
			return (arena_malloc_large(choose_arena(), size, zero));
	}
}

 

 

void *
huge_malloc(size_t size, bool zero)
{
	void *ret;
	size_t csize;
	extent_node_t *node;

	/* Allocate one or more contiguous chunks for this request. */

	csize = CHUNK_CEILING(size);
	if (csize == 0) {
		/* size is large enough to cause size_t wrap-around. */
		return (NULL);
	}

	/* Allocate an extent node with which to track the chunk. */
	node = base_node_alloc();
	if (node == NULL)
		return (NULL);

	ret = chunk_alloc(csize, &zero);
	if (ret == NULL) {
		base_node_dealloc(node);
		return (NULL);
	}

	/* Insert node into huge. */
	node->addr = ret;
	node->size = csize;

	malloc_mutex_lock(&huge_mtx);
	extent_tree_ad_insert(&huge, node);
#ifdef JEMALLOC_STATS
	huge_nmalloc++;
	huge_allocated += csize;
#endif
	malloc_mutex_unlock(&huge_mtx);

#ifdef JEMALLOC_FILL
	if (zero == false) {
		if (opt_junk)
			memset(ret, 0xa5, csize);
		else if (opt_zero)
			memset(ret, 0, csize);
	}
#endif

	return (ret);
}

 

 

calloc

JEMALLOC_ATTR(malloc)
JEMALLOC_ATTR(visibility("default"))
void *
JEMALLOC_P(calloc)(size_t num, size_t size)
{
	void *ret;
	size_t num_size;
#ifdef JEMALLOC_PROF
	prof_thr_cnt_t *cnt;
#endif

	if (malloc_init()) {
		num_size = 0;
		ret = NULL;
		goto RETURN;
	}

	num_size = num * size;
	if (num_size == 0) {
#ifdef JEMALLOC_SYSV
		if ((opt_sysv == false) && ((num == 0) || (size == 0)))
#endif
			num_size = 1;
#ifdef JEMALLOC_SYSV
		else {
			ret = NULL;
			goto RETURN;
		}
#endif
	/*
	 * Try to avoid division here.  We know that it isn't possible to
	 * overflow during multiplication if neither operand uses any of the
	 * most significant half of the bits in a size_t.
	 */
	} else if (((num | size) & (SIZE_T_MAX << (sizeof(size_t) << 2)))
	    && (num_size / size != num)) {
		/* size_t overflow. */
		ret = NULL;
		goto RETURN;
	}

#ifdef JEMALLOC_PROF
	if (opt_prof) {
		if ((cnt = prof_alloc_prep(num_size)) == NULL) {
			ret = NULL;
			goto RETURN;
		}
		if (prof_promote && (uintptr_t)cnt != (uintptr_t)1U && num_size
		    <= small_maxclass) {
			ret = icalloc(small_maxclass+1);
			if (ret != NULL)
				arena_prof_promoted(ret, num_size);
		} else
			ret = icalloc(num_size);
	} else
#endif
		ret = icalloc(num_size);

RETURN:
	if (ret == NULL) {
#ifdef JEMALLOC_XMALLOC
		if (opt_xmalloc) {
			malloc_write("<jemalloc>: Error in calloc(): out of "
			    "memory\n");
			abort();
		}
#endif
		errno = ENOMEM;
	}

#ifdef JEMALLOC_PROF
	if (opt_prof && ret != NULL)
		prof_malloc(ret, cnt);
#endif
	return (ret);
}

 

 

realloc

JEMALLOC_ATTR(visibility("default"))
void *
JEMALLOC_P(realloc)(void *ptr, size_t size)
{
	void *ret;
#ifdef JEMALLOC_PROF
	size_t old_size;
	prof_thr_cnt_t *cnt, *old_cnt;
#endif

	if (size == 0) {
#ifdef JEMALLOC_SYSV
		if (opt_sysv == false)
#endif
			size = 1;
#ifdef JEMALLOC_SYSV
		else {
			if (ptr != NULL) {
#ifdef JEMALLOC_PROF
				if (opt_prof) {
					old_size = isalloc(ptr);
					old_cnt = prof_cnt_get(ptr);
					cnt = NULL;
				}
#endif
				idalloc(ptr);
			}
#ifdef JEMALLOC_PROF
			else if (opt_prof) {
				old_size = 0;
				old_cnt = NULL;
				cnt = NULL;
			}
#endif
			ret = NULL;
			goto RETURN;
		}
#endif
	}

	if (ptr != NULL) {
		assert(malloc_initialized || malloc_initializer ==
		    pthread_self());

#ifdef JEMALLOC_PROF
		if (opt_prof) {
			old_size = isalloc(ptr);
			old_cnt = prof_cnt_get(ptr);
			if ((cnt = prof_alloc_prep(size)) == NULL) {
				ret = NULL;
				goto OOM;
			}
			if (prof_promote && (uintptr_t)cnt != (uintptr_t)1U &&
			    size <= small_maxclass) {
				ret = iralloc(ptr, small_maxclass+1);
				if (ret != NULL)
					arena_prof_promoted(ret, size);
			} else
				ret = iralloc(ptr, size);
		} else
#endif
			ret = iralloc(ptr, size);

#ifdef JEMALLOC_PROF
OOM:
#endif
		if (ret == NULL) {
#ifdef JEMALLOC_XMALLOC
			if (opt_xmalloc) {
				malloc_write("<jemalloc>: Error in realloc(): "
				    "out of memory\n");
				abort();
			}
#endif
			errno = ENOMEM;
		}
	} else {
#ifdef JEMALLOC_PROF
		if (opt_prof) {
			old_size = 0;
			old_cnt = NULL;
		}
#endif
		if (malloc_init()) {
#ifdef JEMALLOC_PROF
			if (opt_prof)
				cnt = NULL;
#endif
			ret = NULL;
		} else {
#ifdef JEMALLOC_PROF
			if (opt_prof) {
				if ((cnt = prof_alloc_prep(size)) == NULL)
					ret = NULL;
				else {
					if (prof_promote && (uintptr_t)cnt !=
					    (uintptr_t)1U && size <=
					    small_maxclass) {
						ret = imalloc(small_maxclass+1);
						if (ret != NULL) {
							arena_prof_promoted(ret,
							    size);
						}
					} else
						ret = imalloc(size);
				}
			} else
#endif
				ret = imalloc(size);
		}

		if (ret == NULL) {
#ifdef JEMALLOC_XMALLOC
			if (opt_xmalloc) {
				malloc_write("<jemalloc>: Error in realloc(): "
				    "out of memory\n");
				abort();
			}
#endif
			errno = ENOMEM;
		}
	}

#ifdef JEMALLOC_SYSV
RETURN:
#endif
#ifdef JEMALLOC_PROF
	if (opt_prof)
		prof_realloc(ret, cnt, ptr, old_size, old_cnt);
#endif
	return (ret);
}

 

 

释放内存

JEMALLOC_ATTR(visibility("default"))
void
JEMALLOC_P(free)(void *ptr)
{

	if (ptr != NULL) {
		assert(malloc_initialized || malloc_initializer ==
		    pthread_self());

#ifdef JEMALLOC_PROF
		if (opt_prof)
			prof_free(ptr);
#endif
		idalloc(ptr);
	}
}