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author | Ashod Nakashian <ashod.nakashian@collabora.co.uk> | 2016-06-14 07:19:20 -0400 |
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committer | Ashod Nakashian <ashnakash@gmail.com> | 2016-06-15 21:28:47 +0000 |
commit | 60e75fb276778459f6055360646d879b8c615d83 (patch) | |
tree | 332c124a2bff614b1483ab5549e56dbdd743d17a /comphelper/qa | |
parent | b43b7a59ca24927c4f4bd90935b4f0075304abe7 (diff) |
tdf#98955 hardware_concurrency not ideal for thread pools
A new static member getPreferredConcurrency added to
comphelper::ThreadPool to return a configurable max
number of threads.
By default the new function returns the hardware_concurrency
value provided by std::thread. When MAX_CONCURRENCY envar is
defined, the return value is limited to whatever is set there.
Three call-sites that used std::thread::hardware_concurrency
have been replaced with getPreferredConcurrency.
Unittests added to cover the functionality of the new member.
Unittests are capped to 4 threads.
Change-Id: I3332e393a88a5ed436316fa712ed920a4b37f4af
Reviewed-on: https://gerrit.libreoffice.org/26254
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Ashod Nakashian <ashnakash@gmail.com>
Diffstat (limited to 'comphelper/qa')
-rw-r--r-- | comphelper/qa/unit/threadpooltest.cxx | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/comphelper/qa/unit/threadpooltest.cxx b/comphelper/qa/unit/threadpooltest.cxx new file mode 100644 index 000000000000..a90d5b0e1db6 --- /dev/null +++ b/comphelper/qa/unit/threadpooltest.cxx @@ -0,0 +1,55 @@ +/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */ +/* + * This file is part of the LibreOffice project. + * + * This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. + */ + +#include <comphelper/threadpool.hxx> +#include "cppunit/TestAssert.h" +#include "cppunit/TestFixture.h" +#include "cppunit/extensions/HelperMacros.h" +#include "cppunit/plugin/TestPlugIn.h" + +#include <stdlib.h> +#include <thread> + +class ThreadPoolTest : public CppUnit::TestFixture +{ +public: + void testPreferredConcurrency(); + + CPPUNIT_TEST_SUITE(ThreadPoolTest); + CPPUNIT_TEST(testPreferredConcurrency); + CPPUNIT_TEST_SUITE_END(); +}; + +void ThreadPoolTest::testPreferredConcurrency() { + + // Check default. + auto nThreads = comphelper::ThreadPool::getPreferredConcurrency(); + sal_Int32 nExpected = 4; // UTs are capped to 4. + CPPUNIT_ASSERT_EQUAL(nExpected, nThreads); + +#ifndef _WIN32_WINNT + // The result should be cached, so this should change anything. + nThreads = std::thread::hardware_concurrency() * 2; + setenv("MAX_CONCURRENCY", std::to_string(nThreads).c_str(), true); + nThreads = comphelper::ThreadPool::getPreferredConcurrency(); + CPPUNIT_ASSERT_MESSAGE("Expected no more than hardware threads", + nThreads <= (sal_Int32)std::thread::hardware_concurrency()); + + // Revert and check. Again, nothing should change. + unsetenv("MAX_CONCURRENCY"); + nThreads = comphelper::ThreadPool::getPreferredConcurrency(); + CPPUNIT_ASSERT_EQUAL(nExpected, nThreads); +#endif +} + +CPPUNIT_TEST_SUITE_REGISTRATION(ThreadPoolTest); + +CPPUNIT_PLUGIN_IMPLEMENT(); + +/* vim:set shiftwidth=4 softtabstop=4 expandtab: */ |