eprof(3)

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 profiling 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.

DATA TYPES

analyze_type() :: procs | total.
trace_pattern_mfa() :: {atom(), atom(), arity() | '_'}.

FUNCTIONS

analyze(TypeOpts) -> ok | nothing_to_analyze when TypeOpts :: analyze_type().

    If TypeOpts is an atom, it is assumed to be a module name, and this call is equivalent to analyze(TypeOpts, []).

    Otherwise, if TypeOpts is a list, it assumed to be a list of options, and this call is equivalent to analyze(procs, TypeOpts).
analyze(Type, Options) -> ok | nothing_to_analyze when Type :: analyze_type(), Options :: [Option], Option :: {filter, Filter} | {sort, Sort}, Filter :: [{calls, non_neg_integer()} | {time, float()}], Sort :: time | calls | mfa.

    Call this function when profiling has been stopped to display the results.

    If Type is procs, the time spent in each function is shown separately for each profiled process.

    If Type is total, the time spent in each function is shown combined for each profiled process.

    Time is shown as percentage of total time and as absolute time in micro seconds.
log(File) -> ok when File :: atom() | file:filename().

    Call this function to ensure that the results displayed by analyze/0,1,2 are printed to the file File as well as to the screen.
profile(Fun) -> {ok, Value} | {error, Reason} when Fun :: fun(() -> term()), Value :: term(), Reason :: term(); (Rootset) -> profiling | {error, Reason} when Rootset :: [atom() | pid()], Reason :: term().

    If FunRootset is a fun, this call is equivalent to profile([], FunRootset).

    If FunRootset is a list, it is assumed to be a Rootset, and this call is equivalent to start_profiling(Rootset).
profile(Fun, Options) -> {ok, Value} | {error, Reason} when Fun :: fun(() -> term()), Options :: [set_on_spawn | {set_on_spawn, boolean()}], Value :: term(), Reason :: term(); (Rootset, Fun) -> {ok, Value} | {error, Reason} when Rootset :: [atom() | pid()], Fun :: fun(() -> term()), Value :: term(), Reason :: term().

    If Arg1 is a fun and Arg2 is list, this call is equivalent to profile([], Arg1, {'_','_','_'}, Arg2).

    If Arg1 is a list and Arg2 is a fun, this call is equivalent to profile(Arg1, Arg2, {'_','_','_'}, Arg1).
profile(Rootset, Module, Function, Args) -> {ok, Value} | {error, Reason} when Rootset :: [atom() | pid()], Module :: module(), Function :: atom(), Args :: [term()], Value :: term(), Reason :: term(); (Rootset, Fun, Pattern, Options) -> {ok, Value} | {error, Reason} when Rootset :: [atom() | pid()], Fun :: fun(() -> term()), Pattern :: trace_pattern_mfa(), Options :: [set_on_spawn | {set_on_spawn, boolean()}], Value :: term(), Reason :: term().

    This function spawns a process that applies a fun or an an function, and then starts profiling for the spawned proceses as well as the processes in Rootset (and any new processes spawned from them).

    If Arg1 is a fun, Arg2 is expected to be a trace pattern, and Arg3 a list of options. In that case, this call is equivalent to:

    profile(Rootset, erlang, apply, [Arg1, []], Arg2, Arg3)

    If Arg1 is an atom, Arg1 is assumed to be a module name, Arg2 the name of the function in that module, and Arg3 a list of arguments to be used when calling that function. In that case, this call is equivalent to:

    profile(Rootset, Arg1, Arg2, Arg3, {'_','_','_'}, [{set_on_spawn, true}])
profile(Rootset, Module, Function, Args, Pattern, Options) -> {ok, Value} | {error, Reason} when Rootset :: [atom() | pid()], Module :: module(), Function :: atom(), Args :: [term()], Pattern :: trace_pattern_mfa(), Options :: [set_on_spawn | {set_on_spawn, boolean()}], Value :: term(), Reason :: term().

    This function spawns a process P that apply(Module, Function, Args), and then starts profiling for P and the processes in Rootset (and any new processes spawned from them).

    Rootset is a list of pids and registered names.

    Information about activity in any profiled process is stored in the Eprof database.

    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 set_on_spawn option will active call time tracing for all processes spawned by processes in the rootset. This is the default behaviour.

    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.
start() -> {ok, Pid} | {error, Reason} when Pid :: pid(), Reason :: {already_started, Pid}.

    Starts the Eprof server which holds the internal state of the collected data.
start_profiling(Rootset, Pattern, Options) -> profiling | {error, Reason} when Rootset :: [atom() | pid()], Pattern :: trace_pattern_mfa(), Options :: [set_on_spawn | {set_on_spawn, boolean()}], 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 a specific module can be selected, and only the code executed in that module will be profiled.

    The set_on_spawn option will active call time tracing for all processes spawned by processes in the rootset. This is the default behaviour.
stop() -> stopped.

    Stops the Eprof server.
stop_profiling() -> profiling_stopped | profiling_already_stopped.

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