OS X Lion Heap profiling requires disabling Position Independent Executable

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Use the heap profiler on OS X Lion
2. Run pprof using output of MallocExtension::instance()->GetHeapSample()

What is the expected output? What do you see instead?
Expect the names of functions to be well named. Instead random memory addresses 
are returned.

What version of the product are you using? On what operating system?

tcmalloc 1.8 and OS X Lion

Please provide any additional information below.

Seems that OSX Lion has introduced Address space layout randomization (a good 
thing!) but pprof cannot decode the random addresses and locate the appropriate 
function.

Using GCC and the following flag solves the problem:

-Wl,-no_pie

See: 

http://developer.apple.com/library/mac/#documentation/Darwin/Reference/ManPages/
man1/ld.1.html
http://developer.apple.com/library/mac/#documentation/Darwin/Reference/ManPages/
man1/gcc.1.html

Hope that helps!
Donovan.

Original issue reported on code.google.com by DonovanH...@gmail.com on 2 Aug 2011 at 11:39

[GoogleCodeExporter]

Thanks for the report.  I would like to understand this better; I wouldn't 
think ASLR should be a problem for us, as I understand how ASLR works (which is 
probably not very well).  It randomizes the base address for each shared 
library loaded into memory, right?  But the correct address is still returned 
by /proc/self/maps (or whatever the OS X equivalent is)?  That information is 
stored in the heap-sample output, so should let us proceed ok.

Or maybe the correct address isn't returned by /proc/self/maps; I could find 
surprisingly little on the web about how ASLR is actually implemented.

I'd love a solution that lets tcmalloc work with aslr, since all OSes are 
getting it.  I guess telling people they have to disable ASLR to do profiling 
isn't the end of the world -- they can still compile the final binary normally 
-- but it's not ideal.

Original comment by csilv...@gmail.com on 3 Aug 2011 at 12:15

• Added labels: Priority-Medium, Type-Defect

[GoogleCodeExporter]

Hi again,

I think vmmap is the OS X equivalent of /proc/self/map

http://developer.apple.com/library/mac/#documentation/Darwin/Reference/ManPages/
man1/vmmap.1.html

Not sure if my case is special because of using 
MallocExtension::instance()->GetHeapSample() rather than HEAPPROFILE and log 
output. Basically I'm dumping the output of GetHeapSample on to a URL for 
realtime profiling.

Will read the code tomorrow and report back any thoughts. Definitely agree the 
less gcc flags, the better!

Donovan.

Original comment by DonovanH...@gmail.com on 3 Aug 2011 at 12:52

[GoogleCodeExporter]

It looks like we actually use dyld_get_image_header() and iterate through that. 
 You can see in src/base/sysinfo.cc.

My guess is you'll want to expose the maps info via a url the same way as the 
GetHeapSample() data.  c.f. docs/pprof_remote_servers.html.  If you set up your 
server as the doc suggests, you can get realtime information directly via 
pprof!  (Maybe that's what you're doing already.)
   pprof  myserver:port/pprof/heap

The hard part -- the part that I think is missing for you now -- is the 
/pprof/symbol support.

Original comment by csilv...@gmail.com on 3 Aug 2011 at 1:31

[GoogleCodeExporter]

Haven't heard anything in a while, so closing.  I think this ended up being not 
a bug for normal use of perftools, but if that's not the case, feel free to 
reopen.

Original comment by csilv...@gmail.com on 18 Oct 2011 at 6:46

• Changed state: NotABug

[GoogleCodeExporter]

Hi,

Can you elaborate how this is 'not a bug for normal use of perftools'? Do you 
mean that is not relevant to Google's normal use, or other people's normal use?

As one of the 'other people' who would like to use this, it really does render 
Goole Performance Tools mostly unusable on OSX for default compilation options.

Thanks,
Travis

Original comment by travi...@traviscj.com on 19 Sep 2013 at 2:32

[GoogleCodeExporter]

Surely "a normal use of perftools" might include any use of pprof and the other 
tools in Mac OS X?

Original comment by denpasho...@gmail.com on 21 Jan 2015 at 3:48