Introduce a ThreadGuard class and use it in ExternalSSTFileTest.PickedLevelBug (#8112)

Summary:
The patch adds a resource management/RAII class called `ThreadGuard`,
which can be used to ensure that the managed thread is joined when the
`ThreadGuard` is destroyed, regardless of whether it is due to the
object going out of scope, an early return, an exception etc. This is
important because if an `std::thread` object is destroyed without having
been joined (or detached) first, the process is aborted (via
`std::terminate`).

For now, `ThreadGuard` is only used in the test case
`ExternalSSTFileTest.PickedLevelBug`; however, it could come in handy
elsewhere in the codebase as well (both in test code and "real" code).
Case in point: in the `PickedLevelBug` test case, with the earlier code we
could end up in the above situation when the following assertion (which is
before the threads are joined) is triggered:

```
ASSERT_FALSE(bg_compact_started.load());
```

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8112

Test Plan:
```
make check
gtest-parallel --repeat=10000 ./external_sst_file_test --gtest_filter="*PickedLevelBug"
```

Reviewed By: riversand963

Differential Revision: D27343185

Pulled By: ltamasi

fbshipit-source-id: 2a8c3aa68bc78cc03ec0dbae909fb25c2cd15c69
main
Levi Tamasi 4 years ago committed by Facebook GitHub Bot
parent af80a78ba4
commit 303cb23a0f
  1. 59
      db/external_sst_file_test.cc
  2. 41
      util/thread_guard.h

@ -16,6 +16,7 @@
#include "rocksdb/sst_file_writer.h" #include "rocksdb/sst_file_writer.h"
#include "test_util/testutil.h" #include "test_util/testutil.h"
#include "util/random.h" #include "util/random.h"
#include "util/thread_guard.h"
#include "utilities/fault_injection_env.h" #include "utilities/fault_injection_env.h"
namespace ROCKSDB_NAMESPACE { namespace ROCKSDB_NAMESPACE {
@ -1305,38 +1306,38 @@ TEST_F(ExternalSSTFileTest, PickedLevelBug) {
ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->EnableProcessing(); ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->EnableProcessing();
// While writing the MANIFEST start a thread that will ask for compaction
Status bg_compact_status; Status bg_compact_status;
ROCKSDB_NAMESPACE::port::Thread bg_compact([&]() {
bg_compact_status =
db_->CompactRange(CompactRangeOptions(), nullptr, nullptr);
});
TEST_SYNC_POINT("ExternalSSTFileTest::PickedLevelBug:2");
// Start a thread that will ingest a new file
Status bg_addfile_status; Status bg_addfile_status;
ROCKSDB_NAMESPACE::port::Thread bg_addfile([&]() {
file_keys = {1, 2, 3};
bg_addfile_status = GenerateAndAddExternalFile(options, file_keys, 1);
});
// Wait for AddFile to start picking levels and writing MANIFEST
TEST_SYNC_POINT("ExternalSSTFileTest::PickedLevelBug:0");
TEST_SYNC_POINT("ExternalSSTFileTest::PickedLevelBug:3");
// We need to verify that no compactions can run while AddFile is {
// ingesting the files into the levels it find suitable. So we will // While writing the MANIFEST start a thread that will ask for compaction
// wait for 2 seconds to give a chance for compactions to run during ThreadGuard bg_compact(port::Thread([&]() {
// this period, and then make sure that no compactions where able to run bg_compact_status =
env_->SleepForMicroseconds(1000000 * 2); db_->CompactRange(CompactRangeOptions(), nullptr, nullptr);
ASSERT_FALSE(bg_compact_started.load()); }));
TEST_SYNC_POINT("ExternalSSTFileTest::PickedLevelBug:2");
// Hold AddFile from finishing writing the MANIFEST
TEST_SYNC_POINT("ExternalSSTFileTest::PickedLevelBug:1"); // Start a thread that will ingest a new file
ThreadGuard bg_addfile(port::Thread([&]() {
bg_addfile.join(); file_keys = {1, 2, 3};
bg_compact.join(); bg_addfile_status = GenerateAndAddExternalFile(options, file_keys, 1);
}));
// Wait for AddFile to start picking levels and writing MANIFEST
TEST_SYNC_POINT("ExternalSSTFileTest::PickedLevelBug:0");
TEST_SYNC_POINT("ExternalSSTFileTest::PickedLevelBug:3");
// We need to verify that no compactions can run while AddFile is
// ingesting the files into the levels it find suitable. So we will
// wait for 2 seconds to give a chance for compactions to run during
// this period, and then make sure that no compactions where able to run
env_->SleepForMicroseconds(1000000 * 2);
ASSERT_FALSE(bg_compact_started.load());
// Hold AddFile from finishing writing the MANIFEST
TEST_SYNC_POINT("ExternalSSTFileTest::PickedLevelBug:1");
}
ASSERT_OK(bg_addfile_status); ASSERT_OK(bg_addfile_status);
ASSERT_OK(bg_compact_status); ASSERT_OK(bg_compact_status);

@ -0,0 +1,41 @@
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
#pragma once
#include "port/port.h"
#include "rocksdb/rocksdb_namespace.h"
namespace ROCKSDB_NAMESPACE {
// Resource management object for threads that joins the thread upon
// destruction. Has unique ownership of the thread object, so copying it is not
// allowed, while moving it transfers ownership.
class ThreadGuard {
public:
ThreadGuard() = default;
explicit ThreadGuard(port::Thread&& thread) : thread_(std::move(thread)) {}
ThreadGuard(const ThreadGuard&) = delete;
ThreadGuard& operator=(const ThreadGuard&) = delete;
ThreadGuard(ThreadGuard&&) noexcept = default;
ThreadGuard& operator=(ThreadGuard&&) noexcept = default;
~ThreadGuard() {
if (thread_.joinable()) {
thread_.join();
}
}
const port::Thread& GetThread() const { return thread_; }
port::Thread& GetThread() { return thread_; }
private:
port::Thread thread_;
};
} // namespace ROCKSDB_NAMESPACE
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