Summary:
Deadlock: a memtable flush holds DB::mutex_ and calls ThreadLocalPtr::Scrape(), which locks ThreadLocalPtr mutex; meanwhile, a thread exit handler locks ThreadLocalPtr mutex and calls SuperVersionUnrefHandle, which tries to lock DB::mutex_.
This deadlock is hit all the time on our workload. It blocks our release.
In general, the problem is that ThreadLocalPtr takes an arbitrary callback and calls it while holding a lock on a global mutex. The same global mutex is (at least in some cases) locked by almost all ThreadLocalPtr methods, on any instance of ThreadLocalPtr. So, there'll be a deadlock if the callback tries to do anything to any instance of ThreadLocalPtr, or waits for another thread to do so.
So, probably the only safe way to use ThreadLocalPtr callbacks is to do only do simple and lock-free things in them.
This PR fixes the deadlock by making sure that local_sv_ never holds the last reference to a SuperVersion, and therefore SuperVersionUnrefHandle never has to do any nontrivial cleanup.
I also searched for other uses of ThreadLocalPtr to see if they may have similar bugs. There's only one other use, in transaction_lock_mgr.cc, and it looks fine.
Closes https://github.com/facebook/rocksdb/pull/3510
Reviewed By: sagar0
Differential Revision: D7005346
Pulled By: al13n321
fbshipit-source-id: 37575591b84f07a891d6659e87e784660fde815f
Summary:
We've had a couple CockroachDB users fail to build RocksDB on exotic platforms, so I figured I'd try my hand at solving these issues upstream. The problems stem from a) `USE_SSE=1` being too aggressive about turning on SSE4.2, even on toolchains that don't support SSE4.2 and b) RocksDB attempting to detect support for thread-local storage based on OS, even though it can vary by compiler on the same OS.
See the individual commit messages for details. Regarding SSE support, this PR should change virtually nothing for non-CMake based builds. `make`, `PORTABLE=1 make`, `USE_SSE=1 make`, and `PORTABLE=1 USE_SSE=1 make` function exactly as before, except that SSE support will be automatically disabled when a simple SSE4.2-using test program fails to compile, as it does on OpenBSD. (OpenBSD's ports GCC supports SSE4.2, but its binutils do not, so `__SSE_4_2__` is defined but an SSE4.2-using program will fail to assemble.) A warning is emitted in this case. The CMake build is modified to support the same set of options, except that `USE_SSE` is spelled `FORCE_SSE42` because `USE_SSE` is rather useless now that we can automatically detect SSE support, and I figure changing options in the CMake build is less disruptive than changing the non-CMake build.
I've tested these changes on all the platforms I can get my hands on (macOS, Windows MSVC, Windows MinGW, and OpenBSD) and it all works splendidly. Let me know if there's anything you object to—I obviously don't mean to break any of your build pipelines in the process of fixing ours downstream.
Closes https://github.com/facebook/rocksdb/pull/2199
Differential Revision: D5054042
Pulled By: yiwu-arbug
fbshipit-source-id: 938e1fc665c049c02ae15698e1409155b8e72171
Summary:
Fixes compile error:
In file included from ./util/statistics.h:17:0,
from ./util/stop_watch.h:8,
from ./util/perf_step_timer.h:9,
from ./util/iostats_context_imp.h:8,
from ./util/posix_logger.h:27,
from ./port/util_logger.h:18,
from ./db/auto_roll_logger.h:15,
from db/auto_roll_logger.cc:6:
./util/thread_local.h:65:16: error: 'function' in namespace 'std' does not name a template type
typedef std::function<void(void*, void*)> FoldFunc;
Closes https://github.com/facebook/rocksdb/pull/1656
Differential Revision: D4318702
Pulled By: yiwu-arbug
fbshipit-source-id: 8c5d17a
Summary:
This function allows the user to provide a custom function to fold all
threads' local data. It will be used in my next diff for aggregating statistics
stored in thread-local data. Note the test case uses atomics as thread-local
values due to the synchronization requirement (documented in code).
Test Plan: unit test
Reviewers: yhchiang, sdong, kradhakrishnan
Reviewed By: kradhakrishnan
Subscribers: andrewkr, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D62049
Summary:
The call stack used to look like this during static initialization:
#0 0x00000000008032d1 in rocksdb::ThreadLocalPtr::StaticMeta::StaticMeta() (this=0x7ffff683b300) at util/thread_local.cc:172
#1 0x00000000008030a7 in rocksdb::ThreadLocalPtr::Instance() () at util/thread_local.cc:135
#2 0x000000000080310f in rocksdb::ThreadLocalPtr::StaticMeta::Mutex() () at util/thread_local.cc:141
#3 0x0000000000803103 in rocksdb::ThreadLocalPtr::StaticMeta::InitSingletons() () at util/thread_local.cc:139
#4 0x000000000080305d in rocksdb::ThreadLocalPtr::InitSingletons() () at util/thread_local.cc:106
It involves outer/inner classes and the call stacks goes
outer->inner->outer->inner, which is too difficult to understand. We can avoid
a level of back-and-forth by skipping StaticMeta::InitSingletons(), which
doesn't initialize anything beyond what ThreadLocalPtr::Instance() already
initializes.
Now the call stack looks like this during static initialization:
#0 0x00000000008032c5 in rocksdb::ThreadLocalPtr::StaticMeta::StaticMeta() (this=0x7ffff683b300) at util/thread_local.cc:170
#1 0x00000000008030a7 in rocksdb::ThreadLocalPtr::Instance() () at util/thread_local.cc:135
#2 0x000000000080305d in rocksdb::ThreadLocalPtr::InitSingletons() () at util/thread_local.cc:106
Test Plan:
unit tests
verify StaticMeta::mutex_ is still initialized in DefaultEnv() (StaticMeta::mutex_ is the only variable intended to be initialized via StaticMeta::InitSingletons() which I removed)
#0 0x00000000005cee17 in rocksdb::port::Mutex::Mutex(bool) (this=0x7ffff69500b0, adaptive=false) at port/port_posix.cc:52
#1 0x0000000000769cf8 in rocksdb::ThreadLocalPtr::StaticMeta::StaticMeta() (this=0x7ffff6950000) at util/thread_local.cc:168
#2 0x0000000000769a53 in rocksdb::ThreadLocalPtr::Instance() () at util/thread_local.cc:133
#3 0x0000000000769a09 in rocksdb::ThreadLocalPtr::InitSingletons() () at util/thread_local.cc:105
#4 0x0000000000647d98 in rocksdb::Env::Default() () at util/env_posix.cc:845
Reviewers: lightmark, yhchiang, sdong
Reviewed By: sdong
Subscribers: arahut, IslamAbdelRahman, yiwu, andrewkr, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D60813
Summary:
When a child thread that uses ThreadLocalPtr, ThreadLocalPtr::OnThreadExit
will be called when that child thread is destroyed. However,
OnThreadExit will try to access a static singleton of ThreadLocalPtr,
which will be destroyed when the main thread exit. As a result,
when a child thread that uses ThreadLocalPtr exits AFTER the main thread
exits, illegal memory access will occur.
This diff includes a test that reproduce this legacy bug.
==2095206==ERROR: AddressSanitizer: heap-use-after-free on address
0x608000007fa0 at pc 0x959b79 bp 0x7f5fa7426b60 sp 0x7f5fa7426b58
READ of size 8 at 0x608000007fa0 thread T1
This patch fix this issue by having the thread local mutex never be deleted
(but will leak small piece of memory at the end.) The patch also describe
a better solution (thread_local) in the comment that requires gcc 4.8.1 and
in latest clang as a future work once we agree to move toward gcc 4.8.
Test Plan:
COMPILE_WITH_ASAN=1 make thread_local_test -j32
./thread_local_test --gtest_filter="*MainThreadDiesFirst"
Reviewers: anthony, hermanlee4, sdong
Reviewed By: sdong
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D53013
Summary:
By default, RocksDB initializes the singletons of ThreadLocalPtr first, then initializes PosixEnv
via static initializer. Destructor terminates objects in reverse order, so terminating PosixEnv
(calling pthread_mutex_lock), then ThreadLocal (calling pthread_mutex_destroy).
However, in certain case, application might initialize PosixEnv first, then ThreadLocalPtr.
This will cause core dump at the end of the program (eg. https://github.com/facebook/mysql-5.6/issues/122)
This patch fix this issue by ensuring the destruction order by moving the global static singletons
to function static singletons. Since function static singletons are initialized when the function is first
called, this property allows us invoke to enforce the construction of the static PosixEnv and the
singletons of ThreadLocalPtr by calling the function where the ThreadLocalPtr singletons belongs
right before we initialize the static PosixEnv.
Test Plan: Verified in the MyRocks.
Reviewers: yoshinorim, IslamAbdelRahman, rven, kradhakrishnan, anthony, sdong, MarkCallaghan
Reviewed By: anthony
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D51789
Summary:
This patch fixes the following clang-build error in util/thread_local.cc by using a cleaner macro blocker:
12:26:31 util/thread_local.cc:157:19: error: declaration shadows a static data member of 'rocksdb::ThreadLocalPtr::StaticMeta' [-Werror,-Wshadow]
12:26:31 ThreadData* tls_ =
12:26:31 ^
12:26:31 util/thread_local.cc:19:66: note: previous declaration is here
12:26:31 __thread ThreadLocalPtr::ThreadData* ThreadLocalPtr::StaticMeta::tls_ = nullptr;
12:26:31 ^
Test Plan: db_test
Reviewers: sdong, anthony, IslamAbdelRahman, igor
Reviewed By: igor
Subscribers: dhruba
Differential Revision: https://reviews.facebook.net/D44043
Summary: This helps Windows port to format their changes, as discussed. Might have formatted some other codes too becasue last 10 commits include more.
Test Plan: Build it.
Reviewers: anthony, IslamAbdelRahman, kradhakrishnan, yhchiang, igor
Reviewed By: igor
Subscribers: leveldb, dhruba
Differential Revision: https://reviews.facebook.net/D41961
Summary: Make RocksDb build and run on Windows to be functionally
complete and performant. All existing test cases run with no
regressions. Performance numbers are in the pull-request.
Test plan: make all of the existing unit tests pass, obtain perf numbers.
Co-authored-by: Praveen Rao praveensinghrao@outlook.com
Co-authored-by: Sherlock Huang baihan.huang@gmail.com
Co-authored-by: Alex Zinoviev alexander.zinoviev@me.com
Co-authored-by: Dmitri Smirnov dmitrism@microsoft.com
Summary:
make singleton a static member instead of dynamic object. This should
also avoid the race on unique_ptr
Test Plan: make all check
Reviewers: igor, haobo, sdong
Reviewed By: igor
CC: leveldb
Differential Revision: https://reviews.facebook.net/D18177
Summary:
Using ThreadLocalPtr as a flag to determine if a mutex is locked or not enables us to implement AssertNotHeld(). It also makes AssertHeld() actually correct.
I had to remove port::Mutex as a dependency for util/thread_local.h, but that's fine since we can just use std::mutex :)
Test Plan: make check
Reviewers: ljin, dhruba, haobo, sdong, yhchiang
Reviewed By: ljin
CC: leveldb
Differential Revision: https://reviews.facebook.net/D18171
Summary:
Add a check at the end of GetImpl to release SuperVersion if it becomes
obsolete. Also do Scrape() inside InstallSuperVersion so it happens more
frequent.
Test Plan:
make all check
running asan_check now
Reviewers: igor, haobo, sdong, dhruba
Reviewed By: haobo
CC: leveldb
Differential Revision: https://reviews.facebook.net/D16641
Summary:
This is not a generic thread local implementation in the sense that it
only takes pointer. But it does support multiple instances per thread
and lets user plugin function to perform cleanup when thread exits or an
instance gets destroyed.
Test Plan: unit test for now
Reviewers: haobo, igor, sdong, dhruba
Reviewed By: igor
CC: leveldb, kailiu
Differential Revision: https://reviews.facebook.net/D16131
