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Limit req: improved handling of negative times.
Negative times can appear since workers only update time on an event
loop iteration start. If a worker was blocked for a long time during
an event loop iteration, it is possible that another worker already
updated the time stored in the node. As such, time since last update
of the node (ms) will be negative.
Previous code used ngx_abs(ms) in the calculations. That is, negative
times were effectively treated as positive ones. As a result, it was
not possible to maintain high request rates, where the same node can be
updated multiple times from during an event loop iteration.
In particular, this affected setups with many SSL handshakes, see
http://mailman.nginx.org/pipermail/nginx/2018-May/056291.html.
Fix is to only update the last update time stored in the node if the
new time is larger than previously stored one. If a future time is
stored in the node, we preserve this time as is.
To prevent breaking things on platforms without monotonic time available
if system time is updated backwards, a safety limit of 60 seconds is
used. If the time stored in the node is more than 60 seconds in the future,
we assume that the time was changed backwards and update lr->last
to the current time.
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Wed, 30 May 2018 15:40:34 +0300 |
parents | 325b3042edd6 |
children |
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# Copyright (C) Igor Sysoev # Copyright (C) Nginx, Inc. if [ "$NGX_PLATFORM" != win32 ]; then ngx_feature="C compiler" ngx_feature_name= ngx_feature_run=yes ngx_feature_incs= ngx_feature_path= ngx_feature_libs= ngx_feature_test= . auto/feature if [ $ngx_found = no ]; then echo echo $0: error: C compiler $CC is not found echo exit 1 fi fi if [ "$CC" = cl ]; then NGX_CC_NAME=msvc echo " + using Microsoft Visual C++ compiler" elif [ "$CC" = wcl386 ]; then NGX_CC_NAME=owc echo " + using Open Watcom C compiler" elif [ "$CC" = bcc32 ]; then NGX_CC_NAME=bcc echo " + using Borland C++ compiler" elif `$CC -V 2>&1 | grep '^Intel(R) C' >/dev/null 2>&1`; then NGX_CC_NAME=icc echo " + using Intel C++ compiler" elif `$CC -v 2>&1 | grep 'gcc version' >/dev/null 2>&1`; then NGX_CC_NAME=gcc echo " + using GNU C compiler" elif `$CC -v 2>&1 | grep 'clang version' >/dev/null 2>&1`; then NGX_CC_NAME=clang echo " + using Clang C compiler" elif `$CC -v 2>&1 | grep 'LLVM version' >/dev/null 2>&1`; then NGX_CC_NAME=clang echo " + using Clang C compiler" elif `$CC -V 2>&1 | grep 'Sun C' >/dev/null 2>&1`; then NGX_CC_NAME=sunc echo " + using Sun C compiler" elif `$CC -V 2>&1 | grep '^Compaq C' >/dev/null 2>&1`; then NGX_CC_NAME=ccc echo " + using Compaq C compiler" elif `$CC -V 2>&1 | grep '^aCC: ' >/dev/null 2>&1`; then NGX_CC_NAME=acc echo " + using HP aC++ compiler" else NGX_CC_NAME=unknown fi