mtmalloc(3MALLOC)					Memory Allocation Library Functions					 mtmalloc(3MALLOC)

NAME

       mtmalloc, mallocctl - MT hot memory allocator

SYNOPSIS

       #include <mtmalloc.h>
       cc -o a.out -lthread -lmtmalloc

       void *malloc(size_t size);

       void free(void *ptr);

       void *memalign(size_t alignment, size_t size);

       void *realloc(void *ptr, size_t size);

       void *valloc(size_t size);

       void mallocctl(int cmd, long value);

DESCRIPTION

       The  malloc()  and free() functions provide a simple general-purpose memory allocation package that is suitable for use in high performance
       multithreaded applications. The suggested use of this library is in multithreaded applications;	it can be used for single threaded  appli-
       cations,  but  there  is  no  advantage in doing so. This library cannot be dynamically loaded with dlopen(3C) during runtime because there
       must be only one manager of the process heap.

       The malloc() function returns a pointer to a block of at least size bytes suitably aligned for any use.

       The argument to free() is a pointer to a block previously allocated by malloc() or realloc(). After  free()  is	performed  this  space	is
       available for further allocation. If  ptr is a null pointer, no action occurs. The free() function does not set errno.

       Undefined  results  will occur if the space assigned by malloc() is overrun or if a random number is handed to free(). A freed pointer that
       is passed to free() will send a	SIGABRT signal to the calling process. This behavior is controlled by mallocctl().

       The memalign() function allocates size bytes on a specified alignment boundary and returns a pointer to the allocated block. The  value	of
       the  returned  address is guaranteed to be an even multiple of alignment. Note that the value of alignment must be a power of two, and must
       be greater than or equal to the size of a word.

       The realloc() function changes the size of the block pointed to by ptr to size bytes and returns a pointer to the (possibly  moved)  block.
       The  contents will be unchanged up to the lesser of the new and old sizes. If the new size of the block requires movement of the block, the
       space for the previous instantiation of the block is freed. If the new size is larger, the contents of the newly allocated portion  of  the
       block  are unspecified. If ptr is NULL, realloc() behaves like malloc() for the specified size. If size is 0 and ptr is not a null pointer,
       the space pointed to is freed.

       The valloc() function has the same effect as malloc(), except that the allocated memory will be aligned to a multiple of the value returned
       by sysconf(_SC_PAGESIZE).

       After possible pointer coercion, each allocation routine returns  a pointer to a space that is suitably aligned	for storage of any type of
       object.

       The malloc(), realloc(), memalign(), and valloc() functions will fail if there is not enough available memory.

       The mallocctl() function controls the behavior of the malloc library. The options fall into two general classes, debugging options and per-
       formance options.

       MTDOUBLEFREE	 Allows  double   free	of  a  pointer.   Setting value to 1 means yes and 0 means no. The default behavior of double free
			 results in a core dump.

       MTDEBUGPATTERN	 Writes misaligned data into the buffer after free(). When the buffer is reallocated, the contents are verified to  ensure
			 that  there was no access to the buffer after the free. If the buffer has been dirtied, a  SIGABRT signal is delivered to
			 the process. Setting  value to 1 means yes and 0 means no. The default behavior is to	not write  misaligned  data.   The
			 pattern used  is 0xdeadbeef. Use of this option results in a performance penalty.

       MTINITBUFFER	 Writes misaligned data into the newly allocated buffer. This option is useful for detecting some accesses before initial-
			 ization. Setting value to 1 means yes and 0 means no. The default behavior is to not write misaligned data to	the  newly
			 allocated buffer. The pattern used is 0xbaddcafe. Use of this option results in a performance penalty.

       MTCHUNKSIZE	 This option changes the size of allocated memory when a pool has exhausted all available memory in the buffer. Increasing
			 this  value allocates more memory for the application.  A substantial	performance gain can  occur  because  the  library
			 makes	fewer  calls   to the OS for more memory. Acceptable number values are between 9 and 256. The default value is	9.
			 This value is multiplied by 8192.

RETURN VALUES

       If there is no available memory, malloc(), realloc(), memalign(), and valloc() return a null pointer. When realloc() is called with size  >
       0  and  returns NULL, the block pointed to by ptr is left intact. If size, nelem, or elsize is 0, either a null pointer or a unique pointer
       that can be passed to free() is returned.

       If malloc() or realloc() returns unsuccessfully, errno will be set to indicate the error.

ERRORS

       The malloc() and realloc() functions will fail if:

       ENOMEM	 The physical limits of the system are exceeded by size bytes of memory which cannot be allocated.

       EAGAIN	 There is not enough memory available to allocate size bytes of memory; but the application could try again later.

USAGE

       Comparative features of the various allocation libraries can be found in the umem_alloc(3MALLOC) manual page.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       brk(2), getrlimit(2), bsdmalloc(3MALLOC), dlopen(3C), malloc(3C), malloc(3MALLOC),  mapmalloc(3MALLOC),	signal.h(3HEAD),  umem_alloc(3MAL-
       LOC), watchmalloc(3MALLOC), attributes(5)

WARNINGS

       Undefined results will occur if the size requested for a block of memory exceeds the maximum size of a process's heap. This information may
       be obtained using  getrlimit().

SunOS 5.11							    21 Mar 2005 						 mtmalloc(3MALLOC)