Hi guys, Thanks to your help, we finally figure out what was happening on FreeBSD, and the attached patch should fix it. Problem was, haproxy relies on what is really undefined behavior in C, with signed integer overflows. gcc and earlier versions of clang behaved as we expected, but newer versions of clang do not, which is why it started to be a problem with FreeBSD 11 (and is probably on other BSDs using clang, and MacOS X).
Thanks again for giving us enough informations to really figure that out, it would have been _tough_ overwise :) Regards, Olivier
>From 163be439a8bc6e5aa1cf3fea0f086d518ddad0a9 Mon Sep 17 00:00:00 2001 From: Olivier Houchard <ohouch...@haproxy.com> Date: Wed, 19 Apr 2017 11:34:10 +0200 Subject: [PATCH] BUG/MAJOR: Use -fwrapv. Haproxy relies on signed integer wraparound on overflow, however this is really an undefined behavior, so the C compiler is allowed to do whatever it wants, and clang does exactly that, and that causes problems when the timer goes from <= INT_MAX to > INT_MAX, and explains the various hangs reported on FreeBSD every 49.7 days. To make sure we get the intended behavior, use -fwrapv for now. A proper fix is to switch everything to unsigned, and it will happen later, but this is simpler, and more likely to be backported to the stable branches. Many thanks to David King, Mark S, Dave Cottlehuber, Slawa Olhovchenkov, Piotr Pawel Stefaniak, and any other I may have forgotten for reporting that and investigating. --- Makefile | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/Makefile b/Makefile index a87e1e2..63db432 100644 --- a/Makefile +++ b/Makefile @@ -131,7 +131,10 @@ DEBUG_CFLAGS = -g #### Compiler-specific flags that may be used to disable some negative over- # optimization or to silence some warnings. -fno-strict-aliasing is needed with # gcc >= 4.4. -SPEC_CFLAGS = -fno-strict-aliasing -Wdeclaration-after-statement +# We rely on signed integer wraparound on overflow, however clang think it +# can do whatever it wants since it's an undefined behavior, so use -fwrapv +# to be sure e get the intended behavior. +SPEC_CFLAGS = -fno-strict-aliasing -Wdeclaration-after-statement -fwrapv #### Memory usage tuning # If small memory footprint is required, you can reduce the buffer size. There -- 2.9.3
