Node.js –prof – Profiling Node.JS Applications

November 6, 2015 - Node.js

Node.js tutorial

This article will help you to find out more information about Node.js –prof, since the following Node.js tutorial sheds light on profiling Node.js applications.

Calling something like “ulimit -n 8192” in your Node.js application runs a shell script before starting the service. Thus, running with Node.js –prof to generates the v8.log

node --prof --prof_lazy app.js

1	node --prof --prof_lazy app.js

Note that there are tools in /node/deps/v8/ that in combination with this command

tools/linux-tick-processor path-of-v8.log

1	tools/linux-tick-processor path-of-v8.log

lead to the following results:

[Shared libraries]:
  ticks  total  nonlib   name
     3    0.0%    0.0%  .../libc-2.13.so

[JavaScript]:
  ticks  total  nonlib   name
     1    0.0%    0.0%  Stub: InstanceofStub

[C++]:
  ticks  total  nonlib   name
    1    0.0%    0.0%  __write
    ...

[GC]:
  ticks  total  nonlib   name
    15    0.0%

[Bottom up (heavy) profile]:
 Note: percentage shows a share of a particular caller in the total
 amount of its parent calls.
 Callers occupying less than 2.0% are not shown.

  ticks parent  name
  ...

[Shared libraries]:

ticks total nonlib name

3 0.0% 0.0% .../libc-2.13.so

[JavaScript]:

ticks total nonlib name

1 0.0% 0.0% Stub: InstanceofStub

[C++]:

ticks total nonlib name

1 0.0% 0.0% __write

...

[GC]:

ticks total nonlib name

15 0.0%

[Bottom up (heavy) profile]:

Note: percentage shows a share of a particular caller in the total

amount of its parent calls.

Callers occupying less than 2.0% are not shown.

ticks parent name

...

For a trace log use this one:

strace -o trace.log -cf node app.js

1	strace -o trace.log -cf node app.js

If you need time, utilize the following command:

time node app.js

1	time node app.js

Other Useful Tools

dtrace

dtrace -o stacks.out -n 'profile-97/execname == "node" && arg1/{
 @[jstack(100, 8000)] = count(); } tick-60s { exit(0); }'

1 2	dtrace -o stacks.out -n 'profile-97/execname == "node" && arg1/{ @[jstack(100, 8000)] = count(); } tick-60s { exit(0); }'

v8-profiler

var profiler = require('v8-profiler');

profiler.startProfiling('startup');
slowStartupFoo();
profiler.stopProfiling('startup');

profiler.takeSnapshot('beforeLeak');
leakyFoo();
profiler.takeSnapshot('afterLeak');

var profiler = require('v8-profiler');

profiler.startProfiling('startup');

slowStartupFoo();

profiler.stopProfiling('startup');

profiler.takeSnapshot('beforeLeak');

leakyFoo();

profiler.takeSnapshot('afterLeak');

node-inspector

node --debug app.js

1	node --debug app.js

node-profiler

var profiler = require('profiler');
//
// <here be code you don't want to profile>
//
profiler.resume();
//
// <performance critical code here>
//
profiler.pause();

var profiler = require('profiler');

// <here be code you don't want to profile>

profiler.resume();

// <performance critical code here>

profiler.pause();

Nodetime

var nodetime = require('nodetime');
nodetime.on('session', function(id) {
 // do something with session id here
});
nodetime.profile();

var nodetime = require('nodetime');

nodetime.on('session', function(id) {

// do something with session id here

});

nodetime.profile();

Callgrind

valgrind --tool=callgrind node app.js

1	valgrind --tool=callgrind node app.js

node-tick – a node.js-runnable v8.log processor

$ node --prof yourprogram
$ node-tick-processor

1 2	$ node --prof yourprogram $ node-tick-processor

node-stackvis – Stacktrace visualization tools

Profile a program:

# dtrace -n 'profile-97/pid == $YOURPID/{ @[jstack(80, 8192)] = count(); }' -c "sleep 30" > dtrace.out

1	# dtrace -n 'profile-97/pid == $YOURPID/{ @[jstack(80, 8192)] = count(); }' -c "sleep 30" > dtrace.out

translate the DTrace output into a flame graph:

# stackvis < dtrace.out > flamegraph.htm

1	# stackvis < dtrace.out > flamegraph.htm

Source

Other tips from the cookbook

Post Tags:n Node.JS node.js --prof Node.js Developer’s Cookbook Node.js tutorial Profiling Node.JS

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