Flaky sanitizer test on ppc64 bot

[Bill Seurer via llvm-commits]

Actually there was a range of revision a bit further on where it worked, 
too.

r279571 (and previous) - works
r279572 - fails
. . . fails
r279642 - fails
r279643 - works
. . . works
r279663 - works
r279664 - fails
(and fails from here on)

IIRC this is the same range or revisions that affected some of of the 
other multithread test cases that are flaky on powerpcle and which are 
currently disabled.

I wonder if some of these multithread tests should be run multiple times 
when the bots run them?

On 03/06/2017 06:42 PM, Kostya Serebryany wrote:
> Good to know, thanks!
> Aleksey is going to start digging around this code very soon.
>
> On Mon, Mar 6, 2017 at 9:10 AM, Bill Seurer <seurer at linux.vnet.ibm.com
> <mailto:seurer at linux.vnet.ibm.com>> wrote:
>
>     I ran a script that dug back through LOTS of revisions and traced
>     the start of this test cases failing to r279572.
>
>     ------------------------------------------------------------------------
>     r279572 | kcc | 2016-08-23 16:19:47 -0500 (Tue, 23 Aug 2016) | 1 line
>
>     [sanitizer] change the 64-bit allocator to use a single array for
>     free-d chunks instead of a lock-free linked list of tranfer batches.
>     This change simplifies the code, makes th
>     e allocator more 'hardened', and will allow simpler code to release
>     RAM to OS. This may also slowdown malloc stress tests due to lock
>     contension, but I did not observe noticeab
>     le slowdown on various real multi-threaded benchmarks.
>
>
>     BTW, I had to set the repeat count of
>     projects/compiler-rt/lib/asan/tests/default/Asan-powerpc64le-with-calls-Test
>     up to 500 in order to get it to consistently fail.
>
>
>     On 03/01/2017 06:24 PM, Kostya Serebryany wrote:
>
>         + more folks
>
>         On Wed, Mar 1, 2017 at 4:23 PM, Matthias Braun <matze at braunis.de
>         <mailto:matze at braunis.de>
>         <mailto:matze at braunis.de <mailto:matze at braunis.de>>> wrote:
>
>             We have another flaky sanitizer test on the ppc64 bot. Just
>         look at
>             the recent history and you see
>             AddressSanitizer-Unit::AddressSanitizer.ManyThreadsTest
>         failing a
>             lot on unrelated commits:
>
>
>         http://lab.llvm.org:8011/builders/clang-ppc64le-linux-multistage?numbuilds=50
>         <http://lab.llvm.org:8011/builders/clang-ppc64le-linux-multistage?numbuilds=50>
>
>         <http://lab.llvm.org:8011/builders/clang-ppc64le-linux-multistage?numbuilds=50
>         <http://lab.llvm.org:8011/builders/clang-ppc64le-linux-multistage?numbuilds=50>>
>
>             Please fix or disable this test.
>
>             - Matthias
>
>
>
>
>     --
>
>     -Bill Seurer
>
>


-- 

-Bill Seurer