CPU PROFILER
------------
See doc/cpu-profiler.html for information about how to use the CPU
profiler and analyze its output.

As a quick-start, do the following after installing this package:

1) Link your executable with -lprofiler
2) Run your executable with the CPUPROFILE environment var set:
     $ CPUPROFILE=/tmp/prof.out <path/to/binary> [binary args]
3) Run pprof to analyze the CPU usage
     $ pprof <path/to/binary> /tmp/prof.out      # -pg-like text output
     $ pprof --gv <path/to/binary> /tmp/prof.out # really cool graphical output

There are other environment variables, besides CPUPROFILE, you can set
to adjust the cpu-profiler behavior; cf "ENVIRONMENT VARIABLES" below.


HEAP CHECKER
------------
In order to catch all heap leaks, this library must be linked *last*
into your executable.  It will not find leaks in libraries listed
after it on the link line.


TCMALLOC
--------
Just link this in to get the advantages of tcmalloc.  See below for
some environment variables you can use with tcmalloc, as well.


ENVIRONMENT VARIABLES
---------------------
These libraries were written to be able to be linked into your
applications all the time.  They'll lie dormant, using no memory or
CPU, until you turn them on.  The easiest way to turn them on is by
setting the appropriate environment variables.  We have many variables
that let you enable/disable features as well as tweak parameters.

CPUPROFILE=<file> -- turns on cpu profiling and dumps data to this file.
PROFILESELECTED=1 -- if set, cpu-profiler will only profile regions of code
                     surrounded with ProfilerEnable()/ProfilerDisable().
FREQUENCY         -- how may interrupts/second the cpu-profiler samples.

TCMALLOC_DEBUG=<level> -- the higher level, the more messages malloc emits
MALLOCSTATS=<level>    -- prints memory-use stats at program-exit