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commit f02dca61aae3771638627409435122820590a5e1 Author: Benno Evers <[email protected]> AuthorDate: Mon Jun 24 14:06:28 2019 +0200 Moved an inline duration for slow DNS logging into a const variable. Moved the 100ms threshold that was used for printing warning messages about slow reverse DNS lookups into a named variable. Review: https://reviews.apache.org/r/70933 --- 3rdparty/libprocess/src/openssl.cpp | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/3rdparty/libprocess/src/openssl.cpp b/3rdparty/libprocess/src/openssl.cpp index 850b6f7..61537bd 100644 --- a/3rdparty/libprocess/src/openssl.cpp +++ b/3rdparty/libprocess/src/openssl.cpp @@ -66,6 +66,14 @@ namespace process { namespace network { namespace openssl { +// A warning is printed when a reverse DNS lookup takes longer +// than this threshold value. According to [1], average DNS query +// times vary between 5ms up to 50ms depending on what the network +// is doing, but most should be down in the < 20ms range. +// +// [1] https://blogs.akamai.com/2017/06/why-you-should-care-about-dns-latency.html +static constexpr Duration SLOW_DNS_WARN_THRESHOLD = Milliseconds(100); + // _Global_ OpenSSL context, initialized via 'initialize'. static SSL_CTX* ctx = nullptr; @@ -817,7 +825,7 @@ Try<Nothing> verify( // Due to MESOS-9339, a slow reverse DNS lookup will cause // serious issues as it blocks the event loop thread. - if (watch.elapsed() > Milliseconds(100)) { + if (watch.elapsed() > SLOW_DNS_WARN_THRESHOLD) { LOG(WARNING) << "Reverse DNS lookup for '" << ip.get() << "'" << " took " << watch.elapsed().ms() << "ms" << ", slowness is problematic (see MESOS-9339)";
