3 .\" Author: Jason Evans
4 .\" Generator: DocBook XSL Stylesheets v1.76.1 <http://docbook.sf.net/>
6 .\" Manual: User Manual
7 .\" Source: jemalloc 3.0.0-0-gfc9b1dbf69f59d7ecfc4ac68da9847e017e1d046
10 .TH "JEMALLOC" "3" "05/11/2012" "jemalloc 3.0.0-0-gfc9b1dbf69f5" "User Manual"
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16 .\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
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31 jemalloc \- general purpose memory allocation functions
34 This manual describes jemalloc 3\&.0\&.0\-0\-gfc9b1dbf69f59d7ecfc4ac68da9847e017e1d046\&. More information can be found at the
35 \m[blue]\fBjemalloc website\fR\m[]\&\s-2\u[1]\d\s+2\&.
41 #include <jemalloc/jemalloc\&.h>
45 .HP \w'void\ *malloc('u
46 .BI "void *malloc(size_t\ " "size" ");"
47 .HP \w'void\ *calloc('u
48 .BI "void *calloc(size_t\ " "number" ", size_t\ " "size" ");"
49 .HP \w'int\ posix_memalign('u
50 .BI "int posix_memalign(void\ **" "ptr" ", size_t\ " "alignment" ", size_t\ " "size" ");"
51 .HP \w'void\ *aligned_alloc('u
52 .BI "void *aligned_alloc(size_t\ " "alignment" ", size_t\ " "size" ");"
53 .HP \w'void\ *realloc('u
54 .BI "void *realloc(void\ *" "ptr" ", size_t\ " "size" ");"
56 .BI "void free(void\ *" "ptr" ");"
57 .SS "Non\-standard API"
58 .HP \w'size_t\ malloc_usable_size('u
59 .BI "size_t malloc_usable_size(const\ void\ *" "ptr" ");"
60 .HP \w'void\ malloc_stats_print('u
61 .BI "void malloc_stats_print(void\ " "(*write_cb)" "\ (void\ *,\ const\ char\ *), void\ *" "cbopaque" ", const\ char\ *" "opts" ");"
62 .HP \w'int\ mallctl('u
63 .BI "int mallctl(const\ char\ *" "name" ", void\ *" "oldp" ", size_t\ *" "oldlenp" ", void\ *" "newp" ", size_t\ " "newlen" ");"
64 .HP \w'int\ mallctlnametomib('u
65 .BI "int mallctlnametomib(const\ char\ *" "name" ", size_t\ *" "mibp" ", size_t\ *" "miblenp" ");"
66 .HP \w'int\ mallctlbymib('u
67 .BI "int mallctlbymib(const\ size_t\ *" "mib" ", size_t\ " "miblen" ", void\ *" "oldp" ", size_t\ *" "oldlenp" ", void\ *" "newp" ", size_t\ " "newlen" ");"
68 .HP \w'void\ (*malloc_message)('u
69 .BI "void (*malloc_message)(void\ *" "cbopaque" ", const\ char\ *" "s" ");"
71 const char *\fImalloc_conf\fR;
72 .SS "Experimental API"
74 .BI "int allocm(void\ **" "ptr" ", size_t\ *" "rsize" ", size_t\ " "size" ", int\ " "flags" ");"
75 .HP \w'int\ rallocm('u
76 .BI "int rallocm(void\ **" "ptr" ", size_t\ *" "rsize" ", size_t\ " "size" ", size_t\ " "extra" ", int\ " "flags" ");"
77 .HP \w'int\ sallocm('u
78 .BI "int sallocm(const\ void\ *" "ptr" ", size_t\ *" "rsize" ", int\ " "flags" ");"
79 .HP \w'int\ dallocm('u
80 .BI "int dallocm(void\ *" "ptr" ", int\ " "flags" ");"
81 .HP \w'int\ nallocm('u
82 .BI "int nallocm(size_t\ *" "rsize" ", size_t\ " "size" ", int\ " "flags" ");"
90 bytes of uninitialized memory\&. The allocated space is suitably aligned (after possible pointer coercion) for storage of any type of object\&.
94 function allocates space for
98 bytes in length\&. The result is identical to calling
103 \fIsize\fR, with the exception that the allocated memory is explicitly initialized to zero bytes\&.
106 \fBposix_memalign\fR\fB\fR
109 bytes of memory such that the allocation\*(Aqs base address is an even multiple of
110 \fIalignment\fR, and returns the allocation in the value pointed to by
111 \fIptr\fR\&. The requested
113 must be a power of 2 at least as large as
114 sizeof(\fBvoid *\fR)\&.
117 \fBaligned_alloc\fR\fB\fR
120 bytes of memory such that the allocation\*(Aqs base address is an even multiple of
121 \fIalignment\fR\&. The requested
123 must be a power of 2\&. Behavior is undefined if
125 is not an integral multiple of
130 function changes the size of the previously allocated memory referenced by
134 bytes\&. The contents of the memory are unchanged up to the lesser of the new and old sizes\&. If the new size is larger, the contents of the newly allocated portion of the memory are undefined\&. Upon success, the memory referenced by
136 is freed and a pointer to the newly allocated memory is returned\&. Note that
138 may move the memory allocation, resulting in a different return value than
144 function behaves identically to
146 for the specified size\&.
150 function causes the allocated memory referenced by
152 to be made available for future allocations\&. If
155 \fBNULL\fR, no action occurs\&.
156 .SS "Non\-standard API"
159 \fBmalloc_usable_size\fR\fB\fR
160 function returns the usable size of the allocation pointed to by
161 \fIptr\fR\&. The return value may be larger than the size that was requested during allocation\&. The
162 \fBmalloc_usable_size\fR\fB\fR
163 function is not a mechanism for in\-place
164 \fBrealloc\fR\fB\fR; rather it is provided solely as a tool for introspection purposes\&. Any discrepancy between the requested allocation size and the size reported by
165 \fBmalloc_usable_size\fR\fB\fR
166 should not be depended on, since such behavior is entirely implementation\-dependent\&.
169 \fBmalloc_stats_print\fR\fB\fR
170 function writes human\-readable summary statistics via the
172 callback function pointer and
176 \fBmalloc_message\fR\fB\fR
180 \fBNULL\fR\&. This function can be called repeatedly\&. General information that never changes during execution can be omitted by specifying "g" as a character within the
183 \fBmalloc_message\fR\fB\fR
186 functions internally, so inconsistent statistics can be reported if multiple threads use these functions simultaneously\&. If
187 \fB\-\-enable\-stats\fR
188 is specified during configuration, \(lqm\(rq and \(lqa\(rq can be specified to omit merged arena and per arena statistics, respectively; \(lqb\(rq and \(lql\(rq can be specified to omit per size class statistics for bins and large objects, respectively\&. Unrecognized characters are silently ignored\&. Note that thread caching may prevent some statistics from being completely up to date, since extra locking would be required to merge counters that track thread cache operations\&.
192 function provides a general interface for introspecting the memory allocator, as well as setting modifiable parameters and triggering actions\&. The period\-separated
194 argument specifies a location in a tree\-structured namespace; see the
196 section for documentation on the tree contents\&. To read a value, pass a pointer via
198 to adequate space to contain the value, and a pointer to its length via
199 \fIoldlenp\fR; otherwise pass
202 \fBNULL\fR\&. Similarly, to write a value, pass a pointer to the value via
203 \fInewp\fR, and its length via
204 \fInewlen\fR; otherwise pass
210 \fBmallctlnametomib\fR\fB\fR
211 function provides a way to avoid repeated name lookups for applications that repeatedly query the same portion of the namespace, by translating a name to a \(lqManagement Information Base\(rq (MIB) that can be passed repeatedly to
212 \fBmallctlbymib\fR\fB\fR\&. Upon successful return from
213 \fBmallctlnametomib\fR\fB\fR,
219 is the lesser of the number of components in
221 and the input value of
222 \fI*miblenp\fR\&. Thus it is possible to pass a
224 that is smaller than the number of period\-separated name components, which results in a partial MIB that can be used as the basis for constructing a complete MIB\&. For name components that are integers (e\&.g\&. the 2 in
225 "arenas\&.bin\&.2\&.size"), the corresponding MIB component will always be that integer\&. Therefore, it is legitimate to construct code like the following:
237 mallctl("arenas\&.nbins", &nbins, &len, NULL, 0);
240 mallnametomib("arenas\&.bin\&.0\&.size", mib, &miblen);
241 for (i = 0; i < nbins; i++) {
245 len = sizeof(bin_size);
246 mallctlbymib(mib, miblen, &bin_size, &len, NULL, 0);
247 /* Do something with bin_size\&.\&.\&. */
253 .SS "Experimental API"
255 The experimental API is subject to change or removal without regard for backward compatibility\&. If
256 \fB\-\-disable\-experimental\fR
257 is specified during configuration, the experimental API is omitted\&.
263 \fBdallocm\fR\fB\fR, and
267 argument that can be used to specify options\&. The functions only check the options that are contextually relevant\&. Use bitwise or (|) operations to specify one or more of the following:
269 \fBALLOCM_LG_ALIGN(\fR\fB\fIla\fR\fR\fB) \fR
271 Align the memory allocation to start at an address that is a multiple of
272 (1 << \fIla\fR)\&. This macro does not validate that
274 is within the valid range\&.
277 \fBALLOCM_ALIGN(\fR\fB\fIa\fR\fR\fB) \fR
279 Align the memory allocation to start at an address that is a multiple of
282 is a power of two\&. This macro does not validate that
289 Initialize newly allocated memory to contain zero bytes\&. In the growing reallocation case, the real size prior to reallocation defines the boundary between untouched bytes and those that are initialized to contain zero bytes\&. If this option is absent, newly allocated memory is uninitialized\&.
294 For reallocation, fail rather than moving the object\&. This constraint can apply to both growth and shrinkage\&.
299 function allocates at least
301 bytes of memory, sets
303 to the base address of the allocation, and sets
305 to the real size of the allocation if
308 \fBNULL\fR\&. Behavior is undefined if
315 function resizes the allocation at
321 to the base address of the allocation if it moved, and sets
323 to the real size of the allocation if
328 is non\-zero, an attempt is made to resize the allocation to be at least
329 \fIsize\fR + \fIextra\fR)
330 bytes, though inability to allocate the extra byte(s) will not by itself result in failure\&. Behavior is undefined if
334 (\fIsize\fR + \fIextra\fR > \fBSIZE_T_MAX\fR)\&.
340 to the real size of the allocation\&.
344 function causes the memory referenced by
346 to be made available for future allocations\&.
350 function allocates no memory, but it performs the same size computation as the
358 to the real size of the allocation that would result from the equivalent
360 function call\&. Behavior is undefined if
366 Once, when the first call is made to one of the memory allocation routines, the allocator initializes its internals based in part on various options that can be specified at compile\- or run\-time\&.
368 The string pointed to by the global variable
369 \fImalloc_conf\fR, the \(lqname\(rq of the file referenced by the symbolic link named
370 /etc/malloc\&.conf, and the value of the environment variable
371 \fBMALLOC_CONF\fR, will be interpreted, in that order, from left to right as options\&.
373 An options string is a comma\-separated list of option:value pairs\&. There is one key corresponding to each
377 section for options documentation)\&. For example,
383 options\&. Some options have boolean values (true/false), others have integer values (base 8, 10, or 16, depending on prefix), and yet others have raw string values\&.
384 .SH "IMPLEMENTATION NOTES"
386 Traditionally, allocators have used
388 to obtain memory, which is suboptimal for several reasons, including race conditions, increased fragmentation, and artificial limitations on maximum usable memory\&. If
389 \fB\-\-enable\-dss\fR
390 is specified during configuration, this allocator uses both
393 \fBsbrk\fR(2), in that order of preference; otherwise only
397 This allocator uses multiple arenas in order to reduce lock contention for threaded programs on multi\-processor systems\&. This works well with regard to threading scalability, but incurs some costs\&. There is a small fixed per\-arena overhead, and additionally, arenas manage memory completely independently of each other, which means a small fixed increase in overall memory fragmentation\&. These overheads are not generally an issue, given the number of arenas normally used\&. Note that using substantially more arenas than the default is not likely to improve performance, mainly due to reduced cache performance\&. However, it may make sense to reduce the number of arenas if an application does not make much use of the allocation functions\&.
399 In addition to multiple arenas, unless
400 \fB\-\-disable\-tcache\fR
401 is specified during configuration, this allocator supports thread\-specific caching for small and large objects, in order to make it possible to completely avoid synchronization for most allocation requests\&. Such caching allows very fast allocation in the common case, but it increases memory usage and fragmentation, since a bounded number of objects can remain allocated in each thread cache\&.
403 Memory is conceptually broken into equal\-sized chunks, where the chunk size is a power of two that is greater than the page size\&. Chunks are always aligned to multiples of the chunk size\&. This alignment makes it possible to find metadata for user objects very quickly\&.
405 User objects are broken into three categories according to size: small, large, and huge\&. Small objects are smaller than one page\&. Large objects are smaller than the chunk size\&. Huge objects are a multiple of the chunk size\&. Small and large objects are managed by arenas; huge objects are managed separately in a single data structure that is shared by all threads\&. Huge objects are used by applications infrequently enough that this single data structure is not a scalability issue\&.
407 Each chunk that is managed by an arena tracks its contents as runs of contiguous pages (unused, backing a set of small objects, or backing one large object)\&. The combination of chunk alignment and chunk page maps makes it possible to determine all metadata regarding small and large allocations in constant time\&.
409 Small objects are managed in groups by page runs\&. Each run maintains a frontier and free list to track which regions are in use\&. Allocation requests that are no more than half the quantum (8 or 16, depending on architecture) are rounded up to the nearest power of two that is at least
410 sizeof(\fBdouble\fR)\&. All other small object size classes are multiples of the quantum, spaced such that internal fragmentation is limited to approximately 25% for all but the smallest size classes\&. Allocation requests that are larger than the maximum small size class, but small enough to fit in an arena\-managed chunk (see the
412 option), are rounded up to the nearest run size\&. Allocation requests that are too large to fit in an arena\-managed chunk are rounded up to the nearest multiple of the chunk size\&.
414 Allocations are packed tightly together, which can be an issue for multi\-threaded applications\&. If you need to assure that allocations do not suffer from cacheline sharing, round your allocation requests up to the nearest multiple of the cacheline size, or specify cacheline alignment when allocating\&.
416 Assuming 4 MiB chunks, 4 KiB pages, and a 16\-byte quantum on a 64\-bit system, the size classes in each category are as shown in
420 .nr an-no-space-flag 1
423 .B Table\ \&1.\ \&Size classes
454 [16, 32, 48, \&.\&.\&., 128]
469 [640, 768, 896, 1024]
474 [1280, 1536, 1792, 2048]
486 [4 KiB, 8 KiB, 12 KiB, \&.\&.\&., 4072 KiB]
493 [4 MiB, 8 MiB, 12 MiB, \&.\&.\&.]
497 .SH "MALLCTL NAMESPACE"
499 The following names are defined in the namespace accessible via the
501 functions\&. Value types are specified in parentheses, their readable/writable statuses are encoded as
505 \-\-, and required build configuration flags follow, if any\&. A name element encoded as
509 indicates an integer component, where the integer varies from 0 to some upper value that must be determined via introspection\&. In the case of
510 "stats\&.arenas\&.<i>\&.*",
514 can be used to access the summation of statistics from all arenas\&. Take special note of the
516 mallctl, which controls refreshing of cached dynamic statistics\&.
518 "version" (\fBconst char *\fR) r\-
520 Return the jemalloc version string\&.
523 "epoch" (\fBuint64_t\fR) rw
525 If a value is passed in, refresh the data from which the
527 functions report values, and increment the epoch\&. Return the current epoch\&. This is useful for detecting whether another thread caused a refresh\&.
530 "config\&.debug" (\fBbool\fR) r\-
532 \fB\-\-enable\-debug\fR
533 was specified during build configuration\&.
536 "config\&.dss" (\fBbool\fR) r\-
538 \fB\-\-enable\-dss\fR
539 was specified during build configuration\&.
542 "config\&.fill" (\fBbool\fR) r\-
544 \fB\-\-enable\-fill\fR
545 was specified during build configuration\&.
548 "config\&.lazy_lock" (\fBbool\fR) r\-
550 \fB\-\-enable\-lazy\-lock\fR
551 was specified during build configuration\&.
554 "config\&.mremap" (\fBbool\fR) r\-
556 \fB\-\-enable\-mremap\fR
557 was specified during build configuration\&.
560 "config\&.munmap" (\fBbool\fR) r\-
562 \fB\-\-enable\-munmap\fR
563 was specified during build configuration\&.
566 "config\&.prof" (\fBbool\fR) r\-
568 \fB\-\-enable\-prof\fR
569 was specified during build configuration\&.
572 "config\&.prof_libgcc" (\fBbool\fR) r\-
574 \fB\-\-disable\-prof\-libgcc\fR
575 was not specified during build configuration\&.
578 "config\&.prof_libunwind" (\fBbool\fR) r\-
580 \fB\-\-enable\-prof\-libunwind\fR
581 was specified during build configuration\&.
584 "config\&.stats" (\fBbool\fR) r\-
586 \fB\-\-enable\-stats\fR
587 was specified during build configuration\&.
590 "config\&.tcache" (\fBbool\fR) r\-
592 \fB\-\-disable\-tcache\fR
593 was not specified during build configuration\&.
596 "config\&.tls" (\fBbool\fR) r\-
598 \fB\-\-disable\-tls\fR
599 was not specified during build configuration\&.
602 "config\&.utrace" (\fBbool\fR) r\-
604 \fB\-\-enable\-utrace\fR
605 was specified during build configuration\&.
608 "config\&.valgrind" (\fBbool\fR) r\-
610 \fB\-\-enable\-valgrind\fR
611 was specified during build configuration\&.
614 "config\&.xmalloc" (\fBbool\fR) r\-
616 \fB\-\-enable\-xmalloc\fR
617 was specified during build configuration\&.
620 "opt\&.abort" (\fBbool\fR) r\-
622 Abort\-on\-warning enabled/disabled\&. If true, most warnings are fatal\&. The process will call
624 in these cases\&. This option is disabled by default unless
625 \fB\-\-enable\-debug\fR
626 is specified during configuration, in which case it is enabled by default\&.
629 "opt\&.lg_chunk" (\fBsize_t\fR) r\-
631 Virtual memory chunk size (log base 2)\&. The default chunk size is 4 MiB (2^22)\&.
634 "opt\&.narenas" (\fBsize_t\fR) r\-
636 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\&.
639 "opt\&.lg_dirty_mult" (\fBssize_t\fR) r\-
641 Per\-arena minimum ratio (log base 2) of active to dirty pages\&. Some dirty unused pages may be allowed to accumulate, within the limit set by the ratio (or one chunk worth of dirty pages, whichever is greater), before informing the kernel about some of those pages via
643 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 disable dirty page purging\&.
646 "opt\&.stats_print" (\fBbool\fR) r\-
648 Enable/disable statistics printing at exit\&. If enabled, the
649 \fBmalloc_stats_print\fR\fB\fR
650 function is called at program exit via an
653 \fB\-\-enable\-stats\fR
654 is specified during configuration, this has the potential to cause deadlock for a multi\-threaded process that exits while one or more threads are executing in the memory allocation functions\&. Therefore, this option should only be used with care; it is primarily intended as a performance tuning aid during application development\&. This option is disabled by default\&.
657 "opt\&.junk" (\fBbool\fR) r\- [\fB\-\-enable\-fill\fR]
659 Junk filling enabled/disabled\&. If enabled, each byte of uninitialized allocated memory will be initialized to
660 0xa5\&. All deallocated memory will be initialized to
661 0x5a\&. This is intended for debugging and will impact performance negatively\&. This option is disabled by default unless
662 \fB\-\-enable\-debug\fR
663 is specified during configuration, in which case it is enabled by default\&.
666 "opt\&.quarantine" (\fBsize_t\fR) r\- [\fB\-\-enable\-fill\fR]
668 Per thread quarantine size in bytes\&. If non\-zero, each thread maintains a FIFO object quarantine that stores up to the specified number of bytes of memory\&. The quarantined memory is not freed until it is released from quarantine, though it is immediately junk\-filled if the
670 option is enabled\&. This feature is of particular use in combination with
671 \m[blue]\fBValgrind\fR\m[]\&\s-2\u[2]\d\s+2, which can detect attempts to access quarantined objects\&. This is intended for debugging and will impact performance negatively\&. The default quarantine size is 0\&.
674 "opt\&.redzone" (\fBbool\fR) r\- [\fB\-\-enable\-fill\fR]
676 Redzones enabled/disabled\&. If enabled, small allocations have redzones before and after them\&. Furthermore, if the
678 option is enabled, the redzones are checked for corruption during deallocation\&. However, the primary intended purpose of this feature is to be used in combination with
679 \m[blue]\fBValgrind\fR\m[]\&\s-2\u[2]\d\s+2, 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\&.
682 "opt\&.zero" (\fBbool\fR) r\- [\fB\-\-enable\-fill\fR]
684 Zero filling enabled/disabled\&. If enabled, each byte of uninitialized allocated memory will be initialized to 0\&. Note that this initialization only happens once for each byte, so
688 calls do not zero memory that was previously allocated\&. This is intended for debugging and will impact performance negatively\&. This option is disabled by default\&.
691 "opt\&.utrace" (\fBbool\fR) r\- [\fB\-\-enable\-utrace\fR]
693 Allocation tracing based on
695 enabled/disabled\&. This option is disabled by default\&.
698 "opt\&.valgrind" (\fBbool\fR) r\- [\fB\-\-enable\-valgrind\fR]
700 \m[blue]\fBValgrind\fR\m[]\&\s-2\u[2]\d\s+2
701 support enabled/disabled\&. If enabled, several other options are automatically modified during options processing to work well with Valgrind:
707 is set to 16 MiB, and
709 is set to true\&. This option is disabled by default\&.
712 "opt\&.xmalloc" (\fBbool\fR) r\- [\fB\-\-enable\-xmalloc\fR]
714 Abort\-on\-out\-of\-memory enabled/disabled\&. If enabled, rather than returning failure for any allocation function, display a diagnostic message on
716 and cause the program to drop core (using
717 \fBabort\fR(3))\&. If an application is designed to depend on this behavior, set the option at compile time by including the following in the source code:
723 malloc_conf = "xmalloc:true";
729 This option is disabled by default\&.
732 "opt\&.tcache" (\fBbool\fR) r\- [\fB\-\-enable\-tcache\fR]
734 Thread\-specific caching enabled/disabled\&. When there are multiple threads, each thread uses a thread\-specific cache for objects up to a certain size\&. Thread\-specific caching allows many allocations to be satisfied without performing any thread synchronization, at the cost of increased memory use\&. See the
735 "opt\&.lg_tcache_max"
736 option for related tuning information\&. This option is enabled by default\&.
739 "opt\&.lg_tcache_max" (\fBsize_t\fR) r\- [\fB\-\-enable\-tcache\fR]
741 Maximum size class (log base 2) to cache in the thread\-specific cache\&. At a minimum, all small size classes are cached, and at a maximum all large size classes are cached\&. The default maximum is 32 KiB (2^15)\&.
744 "opt\&.prof" (\fBbool\fR) r\- [\fB\-\-enable\-prof\fR]
746 Memory profiling enabled/disabled\&. If enabled, profile memory allocation activity\&. See the
748 option for on\-the\-fly activation/deactivation\&. See the
749 "opt\&.lg_prof_sample"
750 option for probabilistic sampling control\&. See the
752 option for control of cumulative sample reporting\&. See the
753 "opt\&.lg_prof_interval"
754 option for information on interval\-triggered profile dumping, the
756 option for information on high\-water\-triggered profile dumping, and the
758 option for final profile dumping\&. Profile output is compatible with the included
760 Perl script, which originates from the
761 \m[blue]\fBgperftools package\fR\m[]\&\s-2\u[3]\d\s+2\&.
764 "opt\&.prof_prefix" (\fBconst char *\fR) r\- [\fB\-\-enable\-prof\fR]
766 Filename prefix for profile dumps\&. If the prefix is set to the empty string, no automatic dumps will occur; this is primarily useful for disabling the automatic final heap dump (which also disables leak reporting, if enabled)\&. The default prefix is
770 "opt\&.prof_active" (\fBbool\fR) r\- [\fB\-\-enable\-prof\fR]
772 Profiling activated/deactivated\&. This is a secondary control mechanism that makes it possible to start the application with profiling enabled (see the
774 option) but inactive, then toggle profiling at any time during program execution with the
776 mallctl\&. This option is enabled by default\&.
779 "opt\&.lg_prof_sample" (\fBssize_t\fR) r\- [\fB\-\-enable\-prof\fR]
781 Average interval (log base 2) between allocation samples, as measured in bytes of allocation activity\&. Increasing the sampling interval decreases profile fidelity, but also decreases the computational overhead\&. The default sample interval is 512 KiB (2^19 B)\&.
784 "opt\&.prof_accum" (\fBbool\fR) r\- [\fB\-\-enable\-prof\fR]
786 Reporting of cumulative object/byte counts in profile dumps enabled/disabled\&. If this option is enabled, every unique backtrace must be stored for the duration of execution\&. Depending on the application, this can impose a large memory overhead, and the cumulative counts are not always of interest\&. This option is disabled by default\&.
789 "opt\&.lg_prof_interval" (\fBssize_t\fR) r\- [\fB\-\-enable\-prof\fR]
791 Average interval (log base 2) between memory profile dumps, as measured in bytes of allocation activity\&. The actual interval between dumps may be sporadic because decentralized allocation counters are used to avoid synchronization bottlenecks\&. Profiles are dumped to files named according to the pattern
792 <prefix>\&.<pid>\&.<seq>\&.i<iseq>\&.heap, where
796 option\&. By default, interval\-triggered profile dumping is disabled (encoded as \-1)\&.
799 "opt\&.prof_gdump" (\fBbool\fR) r\- [\fB\-\-enable\-prof\fR]
801 Trigger a memory profile dump every time the total virtual memory exceeds the previous maximum\&. Profiles are dumped to files named according to the pattern
802 <prefix>\&.<pid>\&.<seq>\&.u<useq>\&.heap, where
806 option\&. This option is disabled by default\&.
809 "opt\&.prof_final" (\fBbool\fR) r\- [\fB\-\-enable\-prof\fR]
813 function to dump final memory usage to a file named according to the pattern
814 <prefix>\&.<pid>\&.<seq>\&.f\&.heap, where
818 option\&. This option is enabled by default\&.
821 "opt\&.prof_leak" (\fBbool\fR) r\- [\fB\-\-enable\-prof\fR]
823 Leak reporting enabled/disabled\&. If enabled, use an
825 function to report memory leaks detected by allocation sampling\&. See the
827 option for information on analyzing heap profile output\&. This option is disabled by default\&.
830 "thread\&.arena" (\fBunsigned\fR) rw
832 Get or set the arena associated with the calling thread\&. The arena index must be less than the maximum number of arenas (see the
834 mallctl)\&. If the specified arena was not initialized beforehand (see the
835 "arenas\&.initialized"
836 mallctl), it will be automatically initialized as a side effect of calling this interface\&.
839 "thread\&.allocated" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
841 Get the total number of bytes ever allocated by the calling thread\&. This counter has the potential to wrap around; it is up to the application to appropriately interpret the counter in such cases\&.
844 "thread\&.allocatedp" (\fBuint64_t *\fR) r\- [\fB\-\-enable\-stats\fR]
846 Get a pointer to the the value that is returned by the
848 mallctl\&. This is useful for avoiding the overhead of repeated
853 "thread\&.deallocated" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
855 Get the total number of bytes ever deallocated by the calling thread\&. This counter has the potential to wrap around; it is up to the application to appropriately interpret the counter in such cases\&.
858 "thread\&.deallocatedp" (\fBuint64_t *\fR) r\- [\fB\-\-enable\-stats\fR]
860 Get a pointer to the the value that is returned by the
861 "thread\&.deallocated"
862 mallctl\&. This is useful for avoiding the overhead of repeated
867 "thread\&.tcache\&.enabled" (\fBbool\fR) rw [\fB\-\-enable\-tcache\fR]
869 Enable/disable calling thread\*(Aqs tcache\&. The tcache is implicitly flushed as a side effect of becoming disabled (see
870 "thread\&.tcache\&.flush")\&.
873 "thread\&.tcache\&.flush" (\fBvoid\fR) \-\- [\fB\-\-enable\-tcache\fR]
875 Flush calling thread\*(Aqs tcache\&. This interface releases all cached objects and internal data structures associated with the calling thread\*(Aqs thread\-specific cache\&. Ordinarily, this interface need not be called, since automatic periodic incremental garbage collection occurs, and the thread cache is automatically discarded when 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\&.
878 "arenas\&.narenas" (\fBunsigned\fR) r\-
880 Maximum number of arenas\&.
883 "arenas\&.initialized" (\fBbool *\fR) r\-
887 booleans\&. Each boolean indicates whether the corresponding arena is initialized\&.
890 "arenas\&.quantum" (\fBsize_t\fR) r\-
895 "arenas\&.page" (\fBsize_t\fR) r\-
900 "arenas\&.tcache_max" (\fBsize_t\fR) r\- [\fB\-\-enable\-tcache\fR]
902 Maximum thread\-cached size class\&.
905 "arenas\&.nbins" (\fBunsigned\fR) r\-
907 Number of bin size classes\&.
910 "arenas\&.nhbins" (\fBunsigned\fR) r\- [\fB\-\-enable\-tcache\fR]
912 Total number of thread cache bin size classes\&.
915 "arenas\&.bin\&.<i>\&.size" (\fBsize_t\fR) r\-
917 Maximum size supported by size class\&.
920 "arenas\&.bin\&.<i>\&.nregs" (\fBuint32_t\fR) r\-
922 Number of regions per page run\&.
925 "arenas\&.bin\&.<i>\&.run_size" (\fBsize_t\fR) r\-
927 Number of bytes per page run\&.
930 "arenas\&.nlruns" (\fBsize_t\fR) r\-
932 Total number of large size classes\&.
935 "arenas\&.lrun\&.<i>\&.size" (\fBsize_t\fR) r\-
937 Maximum size supported by this large size class\&.
940 "arenas\&.purge" (\fBunsigned\fR) \-w
942 Purge unused dirty pages for the specified arena, or for all arenas if none is specified\&.
945 "prof\&.active" (\fBbool\fR) rw [\fB\-\-enable\-prof\fR]
947 Control whether sampling is currently active\&. See the
949 option for additional information\&.
952 "prof\&.dump" (\fBconst char *\fR) \-w [\fB\-\-enable\-prof\fR]
954 Dump a memory profile to the specified file, or if NULL is specified, to a file according to the pattern
955 <prefix>\&.<pid>\&.<seq>\&.m<mseq>\&.heap, where
962 "prof\&.interval" (\fBuint64_t\fR) r\- [\fB\-\-enable\-prof\fR]
964 Average number of bytes allocated between inverval\-based profile dumps\&. See the
965 "opt\&.lg_prof_interval"
966 option for additional information\&.
969 "stats\&.cactive" (\fBsize_t *\fR) r\- [\fB\-\-enable\-stats\fR]
971 Pointer to a counter that contains an approximate count of the current number of bytes in active pages\&. The estimate may be high, but never low, because each arena rounds up to the nearest multiple of the chunk size when computing its contribution to the counter\&. Note that the
973 mallctl has no bearing on this counter\&. Furthermore, counter consistency is maintained via atomic operations, so it is necessary to use an atomic operation in order to guarantee a consistent read when dereferencing the pointer\&.
976 "stats\&.allocated" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
978 Total number of bytes allocated by the application\&.
981 "stats\&.active" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
983 Total number of bytes in active pages allocated by the application\&. This is a multiple of the page size, and greater than or equal to
984 "stats\&.allocated"\&.
987 "stats\&.mapped" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
989 Total number of bytes in chunks mapped on behalf of the application\&. This is a multiple of the chunk size, and is at least as large as
990 "stats\&.active"\&. This does not include inactive chunks\&.
993 "stats\&.chunks\&.current" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
995 Total number of chunks actively mapped on behalf of the application\&. This does not include inactive chunks\&.
998 "stats\&.chunks\&.total" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1000 Cumulative number of chunks allocated\&.
1003 "stats\&.chunks\&.high" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1005 Maximum number of active chunks at any time thus far\&.
1008 "stats\&.huge\&.allocated" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1010 Number of bytes currently allocated by huge objects\&.
1013 "stats\&.huge\&.nmalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1015 Cumulative number of huge allocation requests\&.
1018 "stats\&.huge\&.ndalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1020 Cumulative number of huge deallocation requests\&.
1023 "stats\&.arenas\&.<i>\&.nthreads" (\fBunsigned\fR) r\-
1025 Number of threads currently assigned to arena\&.
1028 "stats\&.arenas\&.<i>\&.pactive" (\fBsize_t\fR) r\-
1030 Number of pages in active runs\&.
1033 "stats\&.arenas\&.<i>\&.pdirty" (\fBsize_t\fR) r\-
1035 Number of pages within unused runs that are potentially dirty, and for which
1036 \fBmadvise\fR\fB\fI\&.\&.\&.\fR\fR\fB \fR\fB\fI\fBMADV_DONTNEED\fR\fR\fR
1037 or similar has not been called\&.
1040 "stats\&.arenas\&.<i>\&.mapped" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1042 Number of mapped bytes\&.
1045 "stats\&.arenas\&.<i>\&.npurge" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1047 Number of dirty page purge sweeps performed\&.
1050 "stats\&.arenas\&.<i>\&.nmadvise" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1053 \fBmadvise\fR\fB\fI\&.\&.\&.\fR\fR\fB \fR\fB\fI\fBMADV_DONTNEED\fR\fR\fR
1054 or similar calls made to purge dirty pages\&.
1057 "stats\&.arenas\&.<i>\&.npurged" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1059 Number of pages purged\&.
1062 "stats\&.arenas\&.<i>\&.small\&.allocated" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1064 Number of bytes currently allocated by small objects\&.
1067 "stats\&.arenas\&.<i>\&.small\&.nmalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1069 Cumulative number of allocation requests served by small bins\&.
1072 "stats\&.arenas\&.<i>\&.small\&.ndalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1074 Cumulative number of small objects returned to bins\&.
1077 "stats\&.arenas\&.<i>\&.small\&.nrequests" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1079 Cumulative number of small allocation requests\&.
1082 "stats\&.arenas\&.<i>\&.large\&.allocated" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1084 Number of bytes currently allocated by large objects\&.
1087 "stats\&.arenas\&.<i>\&.large\&.nmalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1089 Cumulative number of large allocation requests served directly by the arena\&.
1092 "stats\&.arenas\&.<i>\&.large\&.ndalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1094 Cumulative number of large deallocation requests served directly by the arena\&.
1097 "stats\&.arenas\&.<i>\&.large\&.nrequests" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1099 Cumulative number of large allocation requests\&.
1102 "stats\&.arenas\&.<i>\&.bins\&.<j>\&.allocated" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1104 Current number of bytes allocated by bin\&.
1107 "stats\&.arenas\&.<i>\&.bins\&.<j>\&.nmalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1109 Cumulative number of allocations served by bin\&.
1112 "stats\&.arenas\&.<i>\&.bins\&.<j>\&.ndalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1114 Cumulative number of allocations returned to bin\&.
1117 "stats\&.arenas\&.<i>\&.bins\&.<j>\&.nrequests" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1119 Cumulative number of allocation requests\&.
1122 "stats\&.arenas\&.<i>\&.bins\&.<j>\&.nfills" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR \fB\-\-enable\-tcache\fR]
1124 Cumulative number of tcache fills\&.
1127 "stats\&.arenas\&.<i>\&.bins\&.<j>\&.nflushes" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR \fB\-\-enable\-tcache\fR]
1129 Cumulative number of tcache flushes\&.
1132 "stats\&.arenas\&.<i>\&.bins\&.<j>\&.nruns" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1134 Cumulative number of runs created\&.
1137 "stats\&.arenas\&.<i>\&.bins\&.<j>\&.nreruns" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1139 Cumulative number of times the current run from which to allocate changed\&.
1142 "stats\&.arenas\&.<i>\&.bins\&.<j>\&.curruns" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1144 Current number of runs\&.
1147 "stats\&.arenas\&.<i>\&.lruns\&.<j>\&.nmalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1149 Cumulative number of allocation requests for this size class served directly by the arena\&.
1152 "stats\&.arenas\&.<i>\&.lruns\&.<j>\&.ndalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1154 Cumulative number of deallocation requests for this size class served directly by the arena\&.
1157 "stats\&.arenas\&.<i>\&.lruns\&.<j>\&.nrequests" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1159 Cumulative number of allocation requests for this size class\&.
1162 "stats\&.arenas\&.<i>\&.lruns\&.<j>\&.curruns" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1164 Current number of runs for this size class\&.
1166 .SH "DEBUGGING MALLOC PROBLEMS"
1168 When debugging, it is a good idea to configure/build jemalloc with the
1169 \fB\-\-enable\-debug\fR
1171 \fB\-\-enable\-fill\fR
1172 options, and recompile the program with suitable options and symbols for debugger support\&. When so configured, jemalloc incorporates a wide variety of run\-time assertions that catch application errors such as double\-free, write\-after\-free, etc\&.
1174 Programs often accidentally depend on \(lquninitialized\(rq memory actually being filled with zero bytes\&. Junk filling (see the
1176 option) tends to expose such bugs in the form of obviously incorrect results and/or coredumps\&. Conversely, zero filling (see the
1178 option) eliminates the symptoms of such bugs\&. Between these two options, it is usually possible to quickly detect, diagnose, and eliminate such bugs\&.
1180 This implementation does not provide much detail about the problems it detects, because the performance impact for storing such information would be prohibitive\&. However, jemalloc does integrate with the most excellent
1181 \m[blue]\fBValgrind\fR\m[]\&\s-2\u[2]\d\s+2
1183 \fB\-\-enable\-valgrind\fR
1184 configuration option is enabled and the
1186 option is enabled\&.
1187 .SH "DIAGNOSTIC MESSAGES"
1189 If any of the memory allocation/deallocation functions detect an error or warning condition, a message will be printed to file descriptor
1190 \fBSTDERR_FILENO\fR\&. Errors will result in the process dumping core\&. If the
1192 option is set, most warnings are treated as errors\&.
1195 \fImalloc_message\fR
1196 variable allows the programmer to override the function which emits the text strings forming the errors and warnings if for some reason the
1198 file descriptor is not suitable for this\&.
1199 \fBmalloc_message\fR\fB\fR
1202 pointer argument that is
1204 unless overridden by the arguments in a call to
1205 \fBmalloc_stats_print\fR\fB\fR, 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\&.
1207 All messages are prefixed by \(lq<jemalloc>:\(rq\&.
1215 functions return a pointer to the allocated memory if successful; otherwise a
1217 pointer is returned and
1223 \fBposix_memalign\fR\fB\fR
1224 function returns the value 0 if successful; otherwise it returns an error value\&. The
1225 \fBposix_memalign\fR\fB\fR
1226 function will fail if:
1232 parameter is not a power of 2 at least as large as
1233 sizeof(\fBvoid *\fR)\&.
1238 Memory allocation error\&.
1242 \fBaligned_alloc\fR\fB\fR
1243 function returns a pointer to the allocated memory if successful; otherwise a
1245 pointer is returned and
1248 \fBaligned_alloc\fR\fB\fR
1249 function will fail if:
1255 parameter is not a power of 2\&.
1260 Memory allocation error\&.
1265 function returns a pointer, possibly identical to
1266 \fIptr\fR, to the allocated memory if successful; otherwise a
1268 pointer is returned, and
1272 if the error was the result of an allocation failure\&. The
1274 function always leaves the original buffer intact when an error occurs\&.
1278 function returns no value\&.
1279 .SS "Non\-standard API"
1282 \fBmalloc_usable_size\fR\fB\fR
1283 function returns the usable size of the allocation pointed to by
1287 \fBmallctl\fR\fB\fR,
1288 \fBmallctlnametomib\fR\fB\fR, and
1289 \fBmallctlbymib\fR\fB\fR
1290 functions return 0 on success; otherwise they return an error value\&. The functions will fail if:
1298 is too large or too small\&. Alternatively,
1300 is too large or too small; in this case as much data as possible are read despite the error\&.
1306 is too short to hold the requested value\&.
1314 specifies an unknown/invalid value\&.
1319 Attempt to read or write void value, or attempt to write read\-only value\&.
1324 A memory allocation failure occurred\&.
1329 An interface with side effects failed in some way not directly related to
1330 \fBmallctl*\fR\fB\fR
1331 read/write processing\&.
1333 .SS "Experimental API"
1337 \fBrallocm\fR\fB\fR,
1338 \fBsallocm\fR\fB\fR,
1339 \fBdallocm\fR\fB\fR, and
1342 \fBALLOCM_SUCCESS\fR
1343 on success; otherwise they return an error value\&. The
1345 \fBrallocm\fR\fB\fR, and
1347 functions will fail if:
1351 Out of memory\&. Insufficient contiguous memory was available to service the allocation request\&. The
1353 function additionally sets
1356 \fBNULL\fR, whereas the
1364 function will also fail if:
1366 ALLOCM_ERR_NOT_MOVED
1368 \fBALLOCM_NO_MOVE\fR
1369 was specified, but the reallocation request could not be serviced without moving the object\&.
1373 The following environment variable affects the execution of the allocation functions:
1377 If the environment variable
1379 is set, the characters it contains will be interpreted as options\&.
1383 To dump core whenever a problem occurs:
1389 ln \-s \*(Aqabort:true\*(Aq /etc/malloc\&.conf
1395 To specify in the source a chunk size that is 16 MiB:
1401 malloc_conf = "lg_chunk:24";
1414 \fBgetpagesize\fR(3)
1420 \fBrealloc\fR\fB\fR, and
1422 functions conform to ISO/IEC 9899:1990 (\(lqISO C90\(rq)\&.
1425 \fBposix_memalign\fR\fB\fR
1426 function conforms to IEEE Std 1003\&.1\-2001 (\(lqPOSIX\&.1\(rq)\&.
1436 \%http://www.canonware.com/jemalloc/
1441 \%http://valgrind.org/
1446 \%http://code.google.com/p/gperftools/
projects / redis.git / blob