thread_contention.cpp
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//===-- thread_contention.cpp -----------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "gwp_asan/tests/harness.h"
// Note: Compilation of <atomic> and <thread> are extremely expensive for
// non-opt builds of clang.
#include <atomic>
#include <cstdlib>
#include <thread>
#include <vector>
void asyncTask(gwp_asan::GuardedPoolAllocator *GPA,
std::atomic<bool> *StartingGun, unsigned NumIterations) {
while (!*StartingGun) {
// Wait for starting gun.
}
// Get ourselves a new allocation.
for (unsigned i = 0; i < NumIterations; ++i) {
volatile char *Ptr = reinterpret_cast<volatile char *>(
GPA->allocate(GPA->maximumAllocationSize()));
// Do any other threads have access to this page?
EXPECT_EQ(*Ptr, 0);
// Mark the page as from malloc. Wait to see if another thread also takes
// this page.
*Ptr = 'A';
std::this_thread::sleep_for(std::chrono::nanoseconds(10000));
// Check we still own the page.
EXPECT_EQ(*Ptr, 'A');
// And now release it.
*Ptr = 0;
GPA->deallocate(const_cast<char *>(Ptr));
}
}
void runThreadContentionTest(unsigned NumThreads, unsigned NumIterations,
gwp_asan::GuardedPoolAllocator *GPA) {
std::atomic<bool> StartingGun{false};
std::vector<std::thread> Threads;
if (std::thread::hardware_concurrency() < NumThreads) {
NumThreads = std::thread::hardware_concurrency();
}
for (unsigned i = 0; i < NumThreads; ++i) {
Threads.emplace_back(asyncTask, GPA, &StartingGun, NumIterations);
}
StartingGun = true;
for (auto &T : Threads)
T.join();
}
TEST_F(CustomGuardedPoolAllocator, ThreadContention) {
unsigned NumThreads = 4;
unsigned NumIterations = 10000;
InitNumSlots(NumThreads);
runThreadContentionTest(NumThreads, NumIterations, &GPA);
}