Option out of ptr
This macro does not validate that la is within the valid range. Align the memory allocation to start at an address that is a multiple of a , where a is a power of two. This macro does not validate that a is a power of 2. 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 macro is absent, newly allocated memory is uninitialized. Use the thread-specific cache tcache specified by the identifier tc , which must have been acquired via the tcache. This macro does not validate that tc specifies a valid identifier. Do not use a thread-specific cache tcache. Use the arena specified by the index a. This macro has no effect for regions that were allocated via an arena other than the one specified. This macro does not validate that a specifies an arena index in the valid range.
The mallocx function allocates at least size bytes of memory, and returns a pointer to the base address of the allocation. Behavior is undefined if size is 0. The rallocx function resizes the allocation at ptr to be at least size bytes, and returns a pointer to the base address of the resulting allocation, which may or may not have moved from its original location.
The xallocx function resizes the allocation at ptr in place to be at least size bytes, and returns the real size of the allocation. The sallocx function returns the real size of the allocation at ptr. The dallocx function causes the memory referenced by ptr to be made available for future allocations. The sdallocx function is an extension of dallocx with a size parameter to allow the caller to pass in the allocation size as an optimization. The minimum valid input size is the original requested size of the allocation, and the maximum valid input size is the corresponding value returned by nallocx or sallocx.
The mallctl function provides a general interface for introspecting the memory allocator, as well as setting modifiable parameters and triggering actions. To read a value, pass a pointer via oldp to adequate space to contain the value, and a pointer to its length via oldlenp ; otherwise pass NULL and NULL.
Similarly, to write a value, pass a pointer to the value via newp , and its length via newlen ; otherwise pass NULL and 0. For name components that are integers e. Therefore, it is legitimate to construct code like the following:. This function can be called repeatedly. 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. The return value may be larger than the size that was requested during allocation.
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. An options string is a comma-separated list of option: There is one key corresponding to each opt.
Traditionally, allocators have used sbrk 2 to obtain memory, which is suboptimal for several reasons, including race conditions, increased fragmentation, and artificial limitations on maximum usable memory. If sbrk 2 is supported by the operating system, this allocator uses both mmap 2 and sbrk 2 , in that order of preference; otherwise only mmap 2 is used. 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. In addition to multiple arenas, this allocator supports thread-specific caching, 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. Memory is conceptually broken into extents. Extents are always aligned to multiples of the page size. This alignment makes it possible to find metadata for user objects quickly. User objects are broken into two categories according to size: Contiguous small objects comprise a slab, which resides within a single extent, whereas large objects each have their own extents backing them.
Small objects are managed in groups by slabs. Each slab maintains a bitmap 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 sizeof double. 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. The realloc , rallocx , and xallocx functions may resize allocations without moving them under limited circumstances.
Growth and shrinkage trivially succeeds in place as long as the pre-size and post-size both round up to the same size class. No other API guarantees are made regarding in-place resizing, but the current implementation also tries to resize large allocations in place, as long as the pre-size and post-size are both large. For shrinkage to succeed, the extent allocator must support splitting see arena. Growth only succeeds if the trailing memory is currently available, and the extent allocator supports merging.
Assuming 4 KiB pages and a byte quantum on a bit system, the size classes in each category are as shown in Table 1. In the case of stats. These constants can be utilized either via mallctlnametomib followed by mallctlbymib , or via code such as the following:.
Take special note of the epoch mallctl, which controls refreshing of cached dynamic statistics. Return the current epoch. This is useful for detecting whether another thread caused a refresh. When set to true, background threads are created on demand the number of background threads will be no more than the number of CPUs or active arenas.
Threads run periodically, and handle purging asynchronously. When switching off, background threads are terminated synchronously. Note that after fork 2 function, the state in the child process will be disabled regardless the state in parent process. This option is only available on selected pthread-based platforms. Embedded configure-time-specified run-time options string, empty unless --with-malloc-conf was specified during build configuration.
If true, most warnings are fatal. Note that runtime option warnings are not included see opt. The process will call abort 3 in these cases. This option is disabled by default unless --enable-debug is specified during configuration, in which case it is enabled by default.
If true, invalid runtime options are fatal. If true, retain unused virtual memory for later reuse rather than discarding it by calling munmap 2 or equivalent see stats. This option is disabled by default unless discarding virtual memory is known to trigger platform-specific performance problems, e.
Although munmap 2 causes issues on bit Linux as well, retaining virtual memory for bit Linux is disabled by default due to the practical possibility of address space exhaustion. The following settings are supported if sbrk 2 is supported by the operating system: Maximum number of arenas to use for automatic multiplexing of threads and arenas. Per CPU arena mode. Note that no runtime checking regarding the availability of hyper threading is done at the moment.
This option is disabled by default. Approximate time in milliseconds from the creation of a set of unused dirty pages until an equivalent set of unused dirty pages is purged i. Dirty pages are defined as previously having been potentially written to by the application, and therefore consuming physical memory, yet having no current use.
The pages are incrementally purged according to a sigmoidal decay curve that starts and ends with zero purge rate. A decay time of 0 causes all unused dirty pages to be purged immediately upon creation. A decay time of -1 disables purging. The default decay time is 10 seconds. Approximate time in milliseconds from the creation of a set of unused muzzy pages until an equivalent set of unused muzzy pages is purged i.
Muzzy pages are defined as previously having been unused dirty pages that were subsequently purged in a manner that left them subject to the reclamation whims of the operating system e. A decay time of 0 causes all unused muzzy pages to be purged immediately upon creation. If --enable-stats 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.
Furthermore, atexit may allocate memory during application initialization and then deadlock internally when jemalloc in turn calls atexit , so this option is not universally usable though the application can register its own atexit function with equivalent functionality.
Therefore, this option should only be used with care; it is primarily intended as a performance tuning aid during application development. Has no effect unless opt. This is intended for debugging and will impact performance negatively. If enabled, each byte of uninitialized allocated memory will be initialized to 0.
Note that this initialization only happens once for each byte, so realloc and rallocx calls do not zero memory that was previously allocated. If an application is designed to depend on this behavior, set the option at compile time by including the following in the source code:. When there are multiple threads, each thread uses a tcache 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. This option is enabled by default. Maximum size class log base 2 to cache in the thread-specific cache tcache. At a minimum, all small size classes are cached, and at a maximum all large size classes are cached. If enabled, profile memory allocation activity. Profile output is compatible with the jeprof command, which is based on the pprof that is developed as part of the gperftools package.
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 jeprof. This is a secondary control mechanism that makes it possible to start the application with profiling enabled see the opt.
Initial setting for thread. The initial setting for newly created threads can also be changed during execution via the prof. 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.
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. 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. By default, interval-triggered profile dumping is disabled encoded as Set the initial state of prof.
Note that atexit may allocate memory during application initialization and then deadlock internally when jemalloc in turn calls atexit , so this option is not universally usable though the application can register its own atexit function with equivalent functionality. If enabled, use an atexit 3 function to report memory leaks detected by allocation sampling.
Get or set the arena associated with the calling thread. If the specified arena was not initialized beforehand see the arena. 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. Get a pointer to the the value that is returned by the thread. Get the total number of bytes ever deallocated by the calling thread.
The tcache is implicitly flushed as a side effect of becoming disabled see thread. Flush calling thread's thread-specific cache tcache. This interface releases all cached objects and internal data structures associated with the calling thread's tcache. 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.
An internal copy of the name string is created, so the input string need not be maintained after this interface completes execution. The output string of this interface should be copied for non-ephemeral uses, because multiple implementation details can cause asynchronous string deallocation.
Free Tax Filing Assistance. Filing your taxes can be a daunting task. Take heart - help is available. Walk-ins accepted; Handicap accessible. Location English Creek Ave. By appointment only; Please call for hours and days of operation. Open February 8 - April 12, By appointment only; Please call for an appointment.
Open February 5 - April 13, Location 16 Broadway St. Browns Mills , NJ Directions. Site will be closed if it snows. Walk-ins accepted; Drop - off services are also available at this location. Location Burlington Ave. Delanco , NJ Directions. Monday by appointment only; Please call for hours of operation.