eprof (tools v3.5)
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.
Link to this section Summary
Functions
Call this function when profiling has been stopped to display the results per process, that is
This function ensures that the results displayed by analyze/0,1,2 are printed both to the file File and the screen.
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.
Starts the Eprof server which holds the internal state of the collected data.
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.
Stops the Eprof server.
Stops profiling started with start_profiling/1 or prifile/1.
Link to this section Functions
Specs
analyze() -> ok | nothing_to_analyze.
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.
Specs
analyze(Type) -> ok | nothing_to_analyze when Type :: analyze_type().
Specs
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.
log/1
Specs
log(File) -> ok when File :: atom() | file:filename().
This function ensures that the results displayed by analyze/0,1,2 are printed both to the file File and the screen.
Specs
profile(Fun) -> {ok, Value} | {error, Reason}
when Fun :: fun(() -> term()), Value :: term(), Reason :: term();
(Rootset) -> profiling | {error, Reason} when Rootset :: [atom() | pid()], 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 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.
Specs
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().
Specs
profile(Rootset, Fun, Pattern) -> {ok, Value} | {error, Reason}
when
Rootset :: [atom() | pid()],
Fun :: fun(() -> term()),
Pattern :: trace_pattern_mfa(),
Value :: term(),
Reason :: term().
Specs
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().
Specs
profile(Rootset, Module, Function, Args, Pattern) -> {ok, Value} | {error, Reason}
when
Rootset :: [atom() | pid()],
Module :: module(),
Function :: atom(),
Args :: [term()],
Pattern :: trace_pattern_mfa(),
Value :: term(),
Reason :: term().
Specs
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().
start/0
Specs
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.
Specs
start_profiling(Rootset) -> profiling | {error, Reason}
when Rootset :: [atom() | pid()], 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.
Specs
start_profiling(Rootset, Pattern) -> profiling | {error, Reason}
when
Rootset :: [atom() | pid()],
Pattern :: trace_pattern_mfa(),
Reason :: term().
Specs
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().
stop/0
Specs
stop() -> stopped.
Stops the Eprof server.
stop_profiling/0
Specs
stop_profiling() -> profiling_stopped | profiling_already_stopped.
Stops profiling started with start_profiling/1 or prifile/1.