Log Message:
gperftools: updated to 2.16

gperftools-2.16

This release doesn't have major fixes or big headline features, but it has quite \ 
a lot of internal modernizations and cleanups. By the number of commits, 2.16 is \ 
going to be our biggest release ever.

This release's main focus was making our code and building infrastructure \ 
simpler, more straightforward, more portable, and more modern.

Please note that the gperftools 2.16 release will be the last release with the \ 
heap leak checker included. The time has come to drop this feature entirely. All \ 
users should migrate to relevant gcc/clang sanitizers.

Here are the most notable changes:

we've upgraded our C++ standard to C++ 17. Some fraction of our code base was \ 
modernized.

We've integrated (vendored copy of) GoogleTest, and most tests now use it. \ 
GoogleTest has helped us eliminate some legacy code and reduce the number of \ 
tests that use shell scripts.

There are no more unnecessary wrappers around mutexes and threads for unit \ 
tests. We now use C++ standard mutexes and threads in our tests.

We've done the bulk of the work necessary to enable hidden visibility. The most \ 
significant change is that tests no longer reach into libtcmalloc's guts. We use \ 
a special TestingPortal interface instead. We now offer the \ 
--enable-hidden-visibility configure option, which does what it says. But please \ 
note that hidden visibility is off by default for now.

autotools build was significantly refactored, modernized and simplified.

The cmake build has also been radically simplified. The previous version \ 
attempted to duplicate the same complexity that we had in the autotools build \ 
and did not do it very well. More tests now pass under cmake. But please note \ 
that cmake support is still not entirely functional, and we're not yet able to \ 
promise anything about it.

Thread-local storage access and emergency malloc integration have been reworked. \ 
We now support emergency malloc even on systems with emutls and similarly \ 
"bad" TLS support. As a result, backtracing is now more reliable \ 
(e.g., on QNX).

OSX operator new/delete performance has been improved. OSX's malloc performance \ 
is badly compromised by its support of malloc zones, so we cannot help much (the \ 
same applies to much of our competition among memory allocators). But the C++ \ 
new/delete API doesn't have to integrate with this stuff, so we now directly \ 
replace those functions for a sizeable speedup. Note that OSX performance is \ 
still not on par with other "prime tier" OSes due to its lack of \ 
efficient TLS support.

Long deprecated google/ headers have been deleted (use, e.g., \ 
"gperftools/tcmalloc.h" instead)

All clang builds now use -Wthread-safety and actually check thread-safety \ 
declarations

Our code has stopped being incompatible with _TIME_BITS=64 on modern GNU Linux \ 
systems (relevant only for 32-bit systems)

OpenSolaris build has been verified and fixed when needed