heap(1)                   BSD General Commands Manual                  heap(1)

NAME
     heap -- List all the malloc-allocated buffers in the process's heap

SYNOPSIS
     heap [-s | -sortBySize] [-guessNonObjects] [-sumObjectFields]
          [-showSizes] [-addresses all | <classes-pattern>] [-noContent] pid |
          partial-executable-name | memory-graph-file

DESCRIPTION
     heap lists the objects currently allocated on the heap of the specified
     process, as well as summary data.  Objects are categorized by class name,
     type (Objective-C, C++, or CFType), and binary image.  C++ objects are
     identified by the vtable referenced from the start of the object, so with
     multiple inheritance this may not give the precise class of the object.

     The binary image identified for a class is the image which implements the
     class, not necessarily the binary image which caused the objects to be
     allocated at runtime, or which "owns" those objects.

     heap requires one argument -- either the process ID or the full or par-
     tial executable name of the process to examine, or the pathname of a mem-
     ory graph file generated by leaks or the Xcode Memory Graph Debugger.

     The following options are available:

     -s | -sortBySize
             Sort output by total size of class instances, rather than by
             count.

     -guessNonObjects
             Look through the memory contents of each Objective-C object to
             find pointers to malloc'ed blocks (non-objects), such as the
             variable array hanging from an NSArray.  These referenced blocks
             of memory are identified as their offset from the start of the
             object (say "__NSCFArray[12]").  The count, number of bytes, and
             average size of memory blocks referenced from each different
             object offset location are listed in the output.

     -sumObjectFields
             Do the same analysis as with the -guessNonObjects option, but add
             the sizes of those referenced non-object fields into the entries
             for the corresponding objects.

     -showSizes
             Show the distribution of each malloc size for each object,
             instead of summing and averaging the sizes in a single entry.

     -addresses all | <classes-pattern>
             Print the addresses of all malloc blocks found on the heap in
             ascending address order, or the addresses of those objects whose
             full class name is matched by the regular expression <classes-
             pattern>.  The string "all" indicates that the addresses of all
             blocks (both objects and non-objects) should be printed.  The
             <classes-pattern> regular expression is interpreted as an
             extended (modern) regular expression as described by the re_for-
             mat(7) manual page.  Note that toll-freed-bridged CoreFoundation
             and Foundation classes have the "__NSCF" prefix rather than just
             "NS" or "CF".  Examples of valid classes-patterns include:

                   __NSCFString
                   'NS.*'
                   '__NSCFString|__NSCFArray'
                   '.*(String|Array)'
                   non-object

     -noContent
             Do not show object content in -addresses mode.

SEE ALSO
     malloc(3), leaks(1), malloc_history(1), stringdups(1), vmmap(1),
     DevToolsSecurity(1)

     The Xcode developer tools also include Instruments, a graphical applica-
     tion that can give information similar to that provided by heap. The
     Allocations instrument graphically displays dynamic, real-time informa-
     tion about the object and memory use in an application, including back-
     traces of where the allocations occurred.  The Leaks instrument performs
     memory leak analysis.

BSD                              Oct. 17, 2016                             BSD