Heatline - source-annotating profiler

WORK IN PROGRESS, EXPERIMENTAL

Everyone loves profiling code. Usual bottom-up logs like the one below are really fancy:

 [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
     17   18.9%  node::ContextifyScript::New(v8::FunctionCallbackInfo<v8::Value> const&)
     17  100.0%    v8::internal::Builtin_HandleApiCallConstruct(int, v8::internal::Object**, v8::internal::Isolate*)
     17  100.0%      LazyCompile: ~runInThisContext bootstrap_node.js:403:28
     17  100.0%        LazyCompile: NativeModule.compile bootstrap_node.js:485:44
     17  100.0%          LazyCompile: ~NativeModule.require bootstrap_node.js:419:34
      5   29.4%            Function: <anonymous> repl.js:1:11
      4   23.5%            Function: ~<anonymous> internal/repl.js:1:11
      2   11.8%            LazyCompile: ~startup bootstrap_node.js:12:19
      2   11.8%            Function: ~<anonymous> stream.js:1:11
      1    5.9%            LazyCompile: ~setupGlobalVariables bootstrap_node.js:202:32
      1    5.9%            Function: ~<anonymous> util.js:1:11
      1    5.9%            Function: ~<anonymous> tty.js:1:11
      1    5.9%            Function: ~<anonymous> readline.js:1:11

However, in some JavaScript instensive apps it may desirable to find which lines of the functions were executed most.

Heatline

This can be done with heatline pretty easly. heatline is built from two parts: cli tool and a module to be included in user application.

User module

require('heatline')();  // will start a server on port number 11337

NOTE:: node.js should be started with --hydrogen_track_positions in order to get line hits for optimized functions too. Unfortunately this prints tons of stuff to stdout so use wisely

CLI tool

One demo is better than a thousand of words:

How it works?

There is a C++ API in V8 for collecting line hits information, this module has a C++ addon that consumes this API. See deps/v8/include/v8-profiler.h in node.js repo.

LICENSE

This software is licensed under the MIT License.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.