jemalloc — general purpose memory allocation functions
This manual describes jemalloc 3.0.0-0-gfc9b1dbf69f59d7ecfc4ac68da9847e017e1d046. More information +
jemalloc — general purpose memory allocation functions
This manual describes jemalloc 3.2.0-0-g87499f6748ebe4817571e817e9f680ccb5bf54a9. More information can be found at the jemalloc website.
#include <stdlib.h> -#include <jemalloc/jemalloc.h>
void *malloc( | size_t size); |
void *calloc( | size_t number, |
size_t size); |
int posix_memalign( | void **ptr, |
| size_t alignment, | |
size_t size); |
void *aligned_alloc( | size_t alignment, |
size_t size); |
void *realloc( | void *ptr, |
size_t size); |
void free( | void *ptr); |
size_t malloc_usable_size( | const void *ptr); |
int mallctl( | const char *name, |
| void *oldp, | |
| size_t *oldlenp, | |
| void *newp, | |
size_t newlen); |
int mallctlnametomib( | const char *name, |
| size_t *mibp, | |
size_t *miblenp); |
int mallctlbymib( | const size_t *mib, |
| size_t miblen, | |
| void *oldp, | |
| size_t *oldlenp, | |
| void *newp, | |
size_t newlen); |
void (*malloc_message)( | void *cbopaque, |
const char *s); |
const char *malloc_conf;
The malloc() function allocates
size bytes of uninitialized memory. The allocated
space is suitably aligned (after possible pointer coercion) for storage
of any type of object.
The calloc() function allocates
@@ -38,7 +38,7 @@
malloc() for the specified size.
The free() function causes the
allocated memory referenced by ptr to be made
available for future allocations. If ptr is
- NULL, no action occurs.
The malloc_usable_size() function
returns the usable size of the allocation pointed to by
ptr. The return value may be larger than the size
that was requested during allocation. The
@@ -118,7 +118,7 @@ for (i = 0; i < nbins; i++) {
len = sizeof(bin_size);
mallctlbymib(mib, miblen, &bin_size, &len, NULL, 0);
/* Do something with bin_size... */
-}
The experimental API is subject to change or removal without regard
for backward compatibility. If --disable-experimental
is specified during configuration, the experimental API is
omitted.
The allocm(),
@@ -146,7 +146,11 @@ for (i = 0; i < nbins; i++) {
that are initialized to contain zero bytes. If this option is
absent, newly allocated memory is uninitialized.
ALLOCM_NO_MOVEFor reallocation, fail rather than moving the object. This constraint can apply to both growth and - shrinkage.
+ shrinkage.
ALLOCM_ARENA(a)
+ Use the arena specified by the index
+ a. This macro does not validate that
+ a specifies an arena in the valid
+ range.
The allocm() function allocates at
least size bytes of memory, sets
*ptr to the base address of the allocation, and
@@ -404,15 +408,24 @@ for (i = 0; i < nbins; i++) {
(size_t)
r-
Virtual memory chunk size (log base 2). The default - chunk size is 4 MiB (2^22).
opt.dss"
+
+ (const char *)
+ r-
+ dss (sbrk(2)) allocation precedence as + related to mmap(2) allocation. The following + settings are supported: “disabled”, “primary”, + and “secondary” (default).
opt.narenas"
(size_t)
r-
- Maximum number of arenas to use. The default maximum - number of arenas is four times the number of CPUs, or one if there is a - single CPU.
Maximum number of arenas to use for automatic + multiplexing of threads and arenas. The default is four times the + number of CPUs, or one if there is a single CPU.
opt.lg_dirty_mult"
@@ -425,7 +438,7 @@ for (i = 0; i < nbins; i++) {
pages via madvise(2) or a similar system call. This
provides the kernel with sufficient information to recycle dirty pages
if physical memory becomes scarce and the pages remain unused. The
- default minimum ratio is 32:1 (2^5:1); an option value of -1 will
+ default minimum ratio is 8:1 (2^3:1); an option value of -1 will
disable dirty page purging.opt.stats_print"
@@ -454,7 +467,8 @@ for (i = 0; i < nbins; i++) {
0x5a. This is intended for debugging and will
impact performance negatively. This option is disabled by default
unless --enable-debug is specified during
- configuration, in which case it is enabled by default.opt.quarantine"
@@ -470,8 +484,9 @@ for (i = 0; i < nbins; i++) {
option is
enabled. This feature is of particular use in combination with Valgrind, which can detect attempts
to access quarantined objects. This is intended for debugging and will
- impact performance negatively. The default quarantine size is
- 0.opt.redzone"
@@ -489,7 +504,7 @@ for (i = 0; i < nbins; i++) {
which needs redzones in order to do effective buffer overflow/underflow
detection. This option is intended for debugging and will impact
performance negatively. This option is disabled by
- default.opt.zero"
@@ -520,21 +535,9 @@ for (i = 0; i < nbins; i++) {
r-
[--enable-valgrind]
Valgrind
- support enabled/disabled. If enabled, several other options are
- automatically modified during options processing to work well with
- Valgrind:
- "opt.junk"
-
- and
- "opt.zero"
- are set
- to false,
- "opt.quarantine"
- is
- set to 16 MiB, and
- "opt.redzone"
- is set to
- true. This option is disabled by default.
opt.xmalloc"
@@ -566,7 +569,7 @@ malloc_conf = "xmalloc:true";
"opt.lg_tcache_max"
option for related tuning information. This option is enabled by
- default.
opt.lg_tcache_max"
@@ -724,12 +727,8 @@ malloc_conf = "xmalloc:true";
(unsigned)
rw
Get or set the arena associated with the calling
- thread. The arena index must be less than the maximum number of arenas
- (see the
- "arenas.narenas"
-
- mallctl). If the specified arena was not initialized beforehand (see
- the
+ thread. If the specified arena was not initialized beforehand (see the
+
"arenas.initialized"
mallctl), it will be automatically initialized as a side effect of
@@ -804,13 +803,38 @@ malloc_conf = "xmalloc:true";
a thread exits. However, garbage collection is triggered by allocation activity, so it is possible for a thread that stops allocating/deallocating to retain its cache indefinitely, in which case - the developer may find manual flushing useful.
arena.<i>.purge"
+
+ (unsigned)
+ --
+ Purge unused dirty pages for arena <i>, or for
+ all arenas if <i> equals
+ "arenas.narenas"
+ .
+
arena.<i>.dss"
+
+ (const char *)
+ rw
+ Set the precedence of dss allocation as related to mmap
+ allocation for arena <i>, or for all arenas if <i> equals
+
+ "arenas.narenas"
+ . See
+
+ "opt.dss"
+ for supported
+ settings.
+
arenas.narenas"
(unsigned)
r-
- Maximum number of arenas.
Current limit on number of arenas.
arenas.initialized"
@@ -891,7 +915,14 @@ malloc_conf = "xmalloc:true";
(unsigned)
-w
Purge unused dirty pages for the specified arena, or - for all arenas if none is specified.
arenas.extend"
+
+ (unsigned)
+ r-
+ Extend the array of arenas by appending a new arena, + and returning the new arena index.
prof.active"
@@ -966,7 +997,11 @@ malloc_conf = "xmalloc:true";
equal to
"stats.allocated"
.
-
stats.arenas.<i>.pdirty"
+ and pages
+ entirely devoted to allocator metadata.stats.mapped"
@@ -1028,6 +1063,16 @@ malloc_conf = "xmalloc:true";
Cumulative number of huge deallocation requests.
stats.arenas.<i>.dss"
+
+ (const char *)
+ r-
+ dss (sbrk(2)) allocation precedence as
+ related to mmap(2) allocation. See
+ "opt.dss"
+ for details.
+
stats.arenas.<i>.nthreads"
(unsigned)
@@ -1039,7 +1084,7 @@ malloc_conf = "xmalloc:true";
(size_t)
r-
-
Number of pages in active runs.
Number of pages in active runs.
stats.arenas.<i>.pdirty"
@@ -1263,11 +1308,7 @@ malloc_conf = "xmalloc:true";
it detects, because the performance impact for storing such information
would be prohibitive. However, jemalloc does integrate with the most
excellent Valgrind tool if the
- --enable-valgrind configuration option is enabled and the
-
- "opt.valgrind"
- option
- is enabled.
If any of the memory allocation/deallocation functions detect an
+ --enable-valgrind configuration option is enabled.
If any of the memory allocation/deallocation functions detect an
error or warning condition, a message will be printed to file descriptor
All messages are prefixed by
- “STDERR_FILENO. Errors will result in the process
dumping core. If the
@@ -1283,7 +1324,7 @@ malloc_conf = "xmalloc:true";malloc_stats_print(), followed by a string
pointer. Please note that doing anything which tries to allocate memory in
this function is likely to result in a crash or deadlock.<jemalloc>: ”.
The malloc() and
calloc() functions return a pointer to the
allocated memory if successful; otherwise a NULL
pointer is returned and errno is set to
@@ -1311,7 +1352,7 @@ malloc_conf = "xmalloc:true";
allocation failure. The realloc()
function always leaves the original buffer intact when an error occurs.
The free() function returns no
- value.
The malloc_usable_size() function
returns the usable size of the allocation pointed to by
ptr.
The mallctl(),
mallctlnametomib(), and
@@ -1330,7 +1371,7 @@ malloc_conf = "xmalloc:true";
occurred.
An interface with side effects failed in some way
not directly related to mallctl*()
read/write processing.
-