eprof(3erl)						     Erlang Module Definition						       eprof(3erl)

NAME

       eprof - A Time Profiling Tool for Erlang

DESCRIPTION

       The  module eprof provides a set of functions for time profiling of Erlang programs to find out how the execution time is used. The profil-
       ing is done using the Erlang trace BIFs. Tracing of local function calls for a specified set of processes  is  enabled  when  profiling	is
       begun, and disabled when profiling is stopped.

       When using Eprof expect a slowdown in program execution.

EXPORTS

       start() -> {ok,Pid} | {error,Reason}

	      Types  Pid = pid()
		     Reason = {already_started,Pid}

	      Starts the Eprof server which holds the internal state of the collected data.

       start_profiling(Rootset) -> profiling | {error, Reason}
       start_profiling(Rootset,Pattern) -> profiling | {error, Reason}

	      Types  Rootset = [atom() | pid()]
		     Pattern = {Module, Function, Arity}
		     Module = Function = atom()
		     Arity = integer()
		     Reason = term()

	      Starts  profiling for the processes in Rootset (and any new processes spawned from them). Information about activity in any profiled
	      process is stored in the Eprof database.

	      Rootset is a list of pids and registered names.

	      The function returns profiling if tracing could be enabled for all processes in Rootset , or error otherwise.

	      A pattern can be selected to narrow the profiling. For instance ca a specific module be selected and only the  code  processes  exe-
	      cutes in that module will be profiled.

       stop_profiling() -> profiling_stopped | profiling_already_stopped

	      Stops profiling started with start_profiling/1 or profile/1 .

       profile(Fun) -> profiling | {error, Reason}
       profile(Rootset) -> profiling | {error, Reason}
       profile(Rootset,Fun) -> {ok, Value} | {error,Reason}
       profile(Rootset,Fun,Pattern) -> {ok, Value} | {error, Reason}
       profile(Rootset,Module,Function,Args) -> {ok, Value} | {error, Reason}
       profile(Rootset,Module,Function,Args,Pattern) -> {ok, Value} | {error, Reason}

	      Types  Rootset = [atom() | pid()]
		     Fun = fun() -> term()
		     Pattern = {Module, Function, Arity}
		     Module = Function = atom()
		     Args = [term()]
		     Arity = integer()
		     Value = Reason = term()

	      This  function  first  spawns a process P which evaluates Fun() or apply(Module,Function,Args) . Then, it starts profiling for P and
	      the processes in Rootset (and any new processes spawned from them). Information about activity in any profiled process is stored	in
	      the Eprof database.

	      Rootset is a list of pids and registered names.

	      If tracing could be enabled for P and all processes in Rootset , the function returns {ok,Value} when Fun() / apply returns with the
	      value Value , or {error,Reason} if Fun() / apply fails with exit reason Reason . Otherwise it returns {error, Reason} immediately.

	      The programmer must ensure that the function given as argument is truly synchronous and that no work continues  after  the  function
	      has returned a value.

       analyze() -> ok
       analyze(Type) -> ok
       analyze(Type,Options) -> ok

	      Types  Type = procs | total
		     Options = [{filter, Filter} | {sort, Sort}
		     Filter = [{calls, integer()} | {time, float()}]
		     Sort = time | calls | mfa

	      Call this function when profiling has been stopped to display the results per process, that is:

		* how much time has been used by each process, and

		* in which function calls this time has been spent.

	      Call  analyze  with total option when profiling has been stopped to display the results per function call, that is in which function
	      calls the time has been spent.

	      Time is shown as percentage of total time and as absolute time.

       log(File) -> ok

	      Types  File = atom() | string()

	      This function ensures that the results displayed by analyse/0 and total_analyse/0 are printed both to the file File and the screen.

       stop() -> stopped

	      Stops the Eprof server.

Ericsson AB							   tools 2.6.6.3						       eprof(3erl)