build openjdk with fsanitizer=thread
Jie He
Jie.He at arm.com
Tue Feb 25 08:16:20 UTC 2020
Add more report for the previous case, false race between javamain thread and g1 sampling thread.
WARNING: ThreadSanitizer: data race (pid=9770)
Read of size 8 at 0x7b7c00002360 by thread T1:
#0 Mutex::assert_owner(Thread*) /home/wave/workspace/jdk_master/src/hotspot/share/runtime/mutex.cpp:343:3 (libjvm.so+0x1924838)
#1 Monitor::notify() /home/wave/workspace/jdk_master/src/hotspot/share/runtime/mutex.cpp:166:3 (libjvm.so+0x1924c1f)
#2 G1YoungRemSetSamplingThread::stop_service() /home/wave/workspace/jdk_master/src/hotspot/share/gc/g1/g1YoungRemSetSamplingThread.cpp:128:12 (libjvm.so+0x10c50d7)
#3 ConcurrentGCThread::stop() /home/wave/workspace/jdk_master/src/hotspot/share/gc/shared/concurrentGCThread.cpp:65:3 (libjvm.so+0xc9fa11)
#4 G1CollectedHeap::stop() /home/wave/workspace/jdk_master/src/hotspot/share/gc/g1/g1CollectedHeap.cpp:1867:31 (libjvm.so+0xfae058)
#5 before_exit(JavaThread*) /home/wave/workspace/jdk_master/src/hotspot/share/runtime/java.cpp:461:21 (libjvm.so+0x1215b84)
#6 Threads::destroy_vm() /home/wave/workspace/jdk_master/src/hotspot/share/runtime/thread.cpp:4418:3 (libjvm.so+0x1e326ee)
#7 jni_DestroyJavaVM_inner(JavaVM_*) /home/wave/workspace/jdk_master/src/hotspot/share/prims/jni.cpp:3989:7 (libjvm.so+0x137a5eb)
#8 jni_DestroyJavaVM /home/wave/workspace/jdk_master/src/hotspot/share/prims/jni.cpp:4007:14 (libjvm.so+0x137a3ef)
#9 JavaMain /home/wave/workspace/jdk_master/src/java.base/share/native/libjli/java.c:560:5 (libjli.so+0x681b)
Previous write of size 8 at 0x7b7c00002360 by thread T6:
[failed to restore the stack]
Location is heap block of size 3168 at 0x7b7c00001c00 allocated by thread T1:
#0 malloc <null> (java+0x421ee7)
#1 os::malloc(unsigned long, MemoryType, NativeCallStack const&) /home/wave/workspace/jdk_master/src/hotspot/share/runtime/os.cpp:714:18 (libjvm.so+0x19d7e62)
#2 AllocateHeap(unsigned long, MemoryType, NativeCallStack const&, AllocFailStrategy::AllocFailEnum) /home/wave/workspace/jdk_master/src/hotspot/share/memory/allocation.cpp:42:21 (libjvm.so+0x7bfc2d)
#3 Thread::allocate(unsigned long, bool, MemoryType) /home/wave/workspace/jdk_master/src/hotspot/share/runtime/thread.cpp:178:43 (libjvm.so+0x1e20a54)
#4 Thread::operator new(unsigned long) /home/wave/workspace/jdk_master/src/hotspot/share/runtime/thread.hpp:211:52 (libjvm.so+0x86cf52)
#5 G1CollectedHeap::initialize_young_gen_sampling_thread() /home/wave/workspace/jdk_master/src/hotspot/share/gc/g1/g1CollectedHeap.cpp:1642:32 (libjvm.so+0xfaca14)
#6 G1CollectedHeap::initialize() /home/wave/workspace/jdk_master/src/hotspot/share/gc/g1/g1CollectedHeap.cpp:1823:11 (libjvm.so+0xfadd31)
#7 Universe::initialize_heap() /home/wave/workspace/jdk_master/src/hotspot/share/memory/universe.cpp:719:33 (libjvm.so+0x1e88c55)
#8 universe_init() /home/wave/workspace/jdk_master/src/hotspot/share/memory/universe.cpp:653:17 (libjvm.so+0x1e8872b)
#9 init_globals() /home/wave/workspace/jdk_master/src/hotspot/share/runtime/init.cpp:117:17 (libjvm.so+0x11c9bc1)
#10 Threads::create_vm(JavaVMInitArgs*, bool*) /home/wave/workspace/jdk_master/src/hotspot/share/runtime/thread.cpp:3882:17 (libjvm.so+0x1e312a1)
#11 JNI_CreateJavaVM_inner(JavaVM_**, void**, void*) /home/wave/workspace/jdk_master/src/hotspot/share/prims/jni.cpp:3852:12 (libjvm.so+0x1379e74)
#12 JNI_CreateJavaVM /home/wave/workspace/jdk_master/src/hotspot/share/prims/jni.cpp:3935:14 (libjvm.so+0x1379d0f)
#13 InitializeJVM /home/wave/workspace/jdk_master/src/java.base/share/native/libjli/java.c:1538:9 (libjli.so+0x6974)
Thread T1 (tid=9772, running) created by main thread at:
#0 pthread_create <null> (java+0x4233d5)
#1 CallJavaMainInNewThread /home/wave/workspace/jdk_master/src/java.base/unix/native/libjli/java_md_solinux.c:754:9 (libjli.so+0xb53f)
Thread T6 (tid=9778, running) created by thread T1 at:
#0 pthread_create <null> (java+0x4233d5)
#1 os::create_thread(Thread*, os::ThreadType, unsigned long) /home/wave/workspace/jdk_master/src/hotspot/os/linux/os_linux.cpp:926:15 (libjvm.so+0x19e4413)
#2 ConcurrentGCThread::create_and_start(ThreadPriority) /home/wave/workspace/jdk_master/src/hotspot/share/gc/shared/concurrentGCThread.cpp:37:7 (libjvm.so+0xc9f7d4)
#3 G1YoungRemSetSamplingThread::G1YoungRemSetSamplingThread() /home/wave/workspace/jdk_master/src/hotspot/share/gc/g1/g1YoungRemSetSamplingThread.cpp:47:3 (libjvm.so+0x10c49a5)
#4 G1CollectedHeap::initialize_young_gen_sampling_thread() /home/wave/workspace/jdk_master/src/hotspot/share/gc/g1/g1CollectedHeap.cpp:1642:36 (libjvm.so+0xfaca3a)
#5 G1CollectedHeap::initialize() /home/wave/workspace/jdk_master/src/hotspot/share/gc/g1/g1CollectedHeap.cpp:1823:11 (libjvm.so+0xfadd31)
#6 Universe::initialize_heap() /home/wave/workspace/jdk_master/src/hotspot/share/memory/universe.cpp:719:33 (libjvm.so+0x1e88c55)
#7 universe_init() /home/wave/workspace/jdk_master/src/hotspot/share/memory/universe.cpp:653:17 (libjvm.so+0x1e8872b)
#8 init_globals() /home/wave/workspace/jdk_master/src/hotspot/share/runtime/init.cpp:117:17 (libjvm.so+0x11c9bc1)
#9 Threads::create_vm(JavaVMInitArgs*, bool*) /home/wave/workspace/jdk_master/src/hotspot/share/runtime/thread.cpp:3882:17 (libjvm.so+0x1e312a1)
#10 JNI_CreateJavaVM_inner(JavaVM_**, void**, void*) /home/wave/workspace/jdk_master/src/hotspot/share/prims/jni.cpp:3852:12 (libjvm.so+0x1379e74)
#11 JNI_CreateJavaVM /home/wave/workspace/jdk_master/src/hotspot/share/prims/jni.cpp:3935:14 (libjvm.so+0x1379d0f)
#12 InitializeJVM /home/wave/workspace/jdk_master/src/java.base/share/native/libjli/java.c:1538:9 (libjli.so+0x6974)
SUMMARY: ThreadSanitizer: data race /home/wave/workspace/jdk_master/src/hotspot/share/runtime/mutex.cpp:343:3 in Mutex::assert_owner(Thread*)
B.R
Jie He
-----Original Message-----
From: Jie He <Jie.He at arm.com>
Sent: Tuesday, February 25, 2020 4:09 PM
To: Jie He <Jie.He at arm.com>; Dmitry Vyukov <dvyukov at google.com>
Cc: nd <nd at arm.com>; thread-sanitizer <thread-sanitizer at googlegroups.com>; tsan-dev at openjdk.java.net
Subject: RE: build openjdk with fsanitizer=thread
Hi Dmitry
another case that data race exists between javamain thread and G1YoungRemSetSampling Thread, I believe both of them are C++ function threads. But tsan doesn't restore G1 thread stack successfully, and seems to consider there is no lock to protect Mutex's member var _owner.
See the following reports by tsan, code could be found in github https://github.com/openjdk/jdk/tree/master/src/hotspot/share:
WARNING: ThreadSanitizer: data race (pid=9787)
Read of size 8 at 0x7b7c00002360 by thread T1:
#0 Mutex::owned_by_self() const /home/wave/workspace/jdk_master/src/hotspot/share/runtime/mutex.cpp:301:10 (libjvm.so+0x1925966)
#1 assert_lock_strong(Mutex const*) /home/wave/workspace/jdk_master/src/hotspot/share/runtime/mutexLocker.cpp:187:13 (libjvm.so+0x19272fa)
#2 MutexLocker::~MutexLocker() /home/wave/workspace/jdk_master/src/hotspot/share/runtime/mutexLocker.hpp:237:7 (libjvm.so+0x33da8a)
#3 G1YoungRemSetSamplingThread::stop_service() /home/wave/workspace/jdk_master/src/hotspot/share/gc/g1/g1YoungRemSetSamplingThread.cpp:129:1 (libjvm.so+0x10c50e0)
#4 ConcurrentGCThread::stop() /home/wave/workspace/jdk_master/src/hotspot/share/gc/shared/concurrentGCThread.cpp:65:3 (libjvm.so+0xc9fa11)
#5 G1CollectedHeap::stop() /home/wave/workspace/jdk_master/src/hotspot/share/gc/g1/g1CollectedHeap.cpp:1867:31 (libjvm.so+0xfae058)
#6 before_exit(JavaThread*) /home/wave/workspace/jdk_master/src/hotspot/share/runtime/java.cpp:461:21 (libjvm.so+0x1215b84)
#7 Threads::destroy_vm() /home/wave/workspace/jdk_master/src/hotspot/share/runtime/thread.cpp:4418:3 (libjvm.so+0x1e326ee)
#8 jni_DestroyJavaVM_inner(JavaVM_*) /home/wave/workspace/jdk_master/src/hotspot/share/prims/jni.cpp:3989:7 (libjvm.so+0x137a5eb)
#9 jni_DestroyJavaVM /home/wave/workspace/jdk_master/src/hotspot/share/prims/jni.cpp:4007:14 (libjvm.so+0x137a3ef)
#10 JavaMain /home/wave/workspace/jdk_master/src/java.base/share/native/libjli/java.c:560:5 (libjli.so+0x681b)
Previous write of size 8 at 0x7b7c00002360 by thread T6:
[failed to restore the stack]
Location is heap block of size 3168 at 0x7b7c00001c00 allocated by thread T1:
#0 malloc <null> (java+0x421ee7)
#1 os::malloc(unsigned long, MemoryType, NativeCallStack const&) /home/wave/workspace/jdk_master/src/hotspot/share/runtime/os.cpp:714:18 (libjvm.so+0x19d7e62)
#2 AllocateHeap(unsigned long, MemoryType, NativeCallStack const&, AllocFailStrategy::AllocFailEnum) /home/wave/workspace/jdk_master/src/hotspot/share/memory/allocation.cpp:42:21 (libjvm.so+0x7bfc2d)
#3 Thread::allocate(unsigned long, bool, MemoryType) /home/wave/workspace/jdk_master/src/hotspot/share/runtime/thread.cpp:178:43 (libjvm.so+0x1e20a54)
#4 Thread::operator new(unsigned long) /home/wave/workspace/jdk_master/src/hotspot/share/runtime/thread.hpp:211:52 (libjvm.so+0x86cf52)
#5 G1CollectedHeap::initialize_young_gen_sampling_thread() /home/wave/workspace/jdk_master/src/hotspot/share/gc/g1/g1CollectedHeap.cpp:1642:32 (libjvm.so+0xfaca14)
#6 G1CollectedHeap::initialize() /home/wave/workspace/jdk_master/src/hotspot/share/gc/g1/g1CollectedHeap.cpp:1823:11 (libjvm.so+0xfadd31)
#7 Universe::initialize_heap() /home/wave/workspace/jdk_master/src/hotspot/share/memory/universe.cpp:719:33 (libjvm.so+0x1e88c55)
#8 universe_init() /home/wave/workspace/jdk_master/src/hotspot/share/memory/universe.cpp:653:17 (libjvm.so+0x1e8872b)
#9 init_globals() /home/wave/workspace/jdk_master/src/hotspot/share/runtime/init.cpp:117:17 (libjvm.so+0x11c9bc1)
#10 Threads::create_vm(JavaVMInitArgs*, bool*) /home/wave/workspace/jdk_master/src/hotspot/share/runtime/thread.cpp:3882:17 (libjvm.so+0x1e312a1)
#11 JNI_CreateJavaVM_inner(JavaVM_**, void**, void*) /home/wave/workspace/jdk_master/src/hotspot/share/prims/jni.cpp:3852:12 (libjvm.so+0x1379e74)
#12 JNI_CreateJavaVM /home/wave/workspace/jdk_master/src/hotspot/share/prims/jni.cpp:3935:14 (libjvm.so+0x1379d0f)
#13 InitializeJVM /home/wave/workspace/jdk_master/src/java.base/share/native/libjli/java.c:1538:9 (libjli.so+0x6974)
Thread T1 (tid=9789, running) created by main thread at:
#0 pthread_create <null> (java+0x4233d5)
#1 CallJavaMainInNewThread /home/wave/workspace/jdk_master/src/java.base/unix/native/libjli/java_md_solinux.c:754:9 (libjli.so+0xb53f)
Thread T6 (tid=9795, running) created by thread T1 at:
#0 pthread_create <null> (java+0x4233d5)
#1 os::create_thread(Thread*, os::ThreadType, unsigned long) /home/wave/workspace/jdk_master/src/hotspot/os/linux/os_linux.cpp:926:15 (libjvm.so+0x19e4413)
#2 ConcurrentGCThread::create_and_start(ThreadPriority) /home/wave/workspace/jdk_master/src/hotspot/share/gc/shared/concurrentGCThread.cpp:37:7 (libjvm.so+0xc9f7d4)
#3 G1YoungRemSetSamplingThread::G1YoungRemSetSamplingThread() /home/wave/workspace/jdk_master/src/hotspot/share/gc/g1/g1YoungRemSetSamplingThread.cpp:47:3 (libjvm.so+0x10c49a5)
#4 G1CollectedHeap::initialize_young_gen_sampling_thread() /home/wave/workspace/jdk_master/src/hotspot/share/gc/g1/g1CollectedHeap.cpp:1642:36 (libjvm.so+0xfaca3a)
#5 G1CollectedHeap::initialize() /home/wave/workspace/jdk_master/src/hotspot/share/gc/g1/g1CollectedHeap.cpp:1823:11 (libjvm.so+0xfadd31)
#6 Universe::initialize_heap() /home/wave/workspace/jdk_master/src/hotspot/share/memory/universe.cpp:719:33 (libjvm.so+0x1e88c55)
#7 universe_init() /home/wave/workspace/jdk_master/src/hotspot/share/memory/universe.cpp:653:17 (libjvm.so+0x1e8872b)
#8 init_globals() /home/wave/workspace/jdk_master/src/hotspot/share/runtime/init.cpp:117:17 (libjvm.so+0x11c9bc1)
#9 Threads::create_vm(JavaVMInitArgs*, bool*) /home/wave/workspace/jdk_master/src/hotspot/share/runtime/thread.cpp:3882:17 (libjvm.so+0x1e312a1)
#10 JNI_CreateJavaVM_inner(JavaVM_**, void**, void*) /home/wave/workspace/jdk_master/src/hotspot/share/prims/jni.cpp:3852:12 (libjvm.so+0x1379e74)
#11 JNI_CreateJavaVM /home/wave/workspace/jdk_master/src/hotspot/share/prims/jni.cpp:3935:14 (libjvm.so+0x1379d0f)
#12 InitializeJVM /home/wave/workspace/jdk_master/src/java.base/share/native/libjli/java.c:1538:9 (libjli.so+0x6974)
SUMMARY: ThreadSanitizer: data race /home/wave/workspace/jdk_master/src/hotspot/share/runtime/mutex.cpp:301:10 in Mutex::owned_by_self() const
B.R
Jie He
-----Original Message-----
From: tsan-dev <tsan-dev-bounces at openjdk.java.net> On Behalf Of Jie He
Sent: Tuesday, February 25, 2020 2:19 PM
To: Dmitry Vyukov <dvyukov at google.com>
Cc: nd <nd at arm.com>; thread-sanitizer <thread-sanitizer at googlegroups.com>; tsan-dev at openjdk.java.net
Subject: RE: build openjdk with fsanitizer=thread
Hi Dmitry
Yes, so I don't think the first 2 classes of warnings are data race, they are out of scope of tsan.
Currently, I'm not sure if the second thread is JIT thread.
But seems the second thread knows a tsan_read8 behavior happened at least in IR level.
like the following tsan reports, I have changed the history_size to 4:
WARNING: ThreadSanitizer: data race (pid=9726)
Write of size 8 at 0x7b1800003ab0 by thread T1:
#0 ChunkPool::free(Chunk*) /home/wave/workspace/jdk_master/src/hotspot/share/memory/arena.cpp:93:16 (libjvm.so+0x7e6fe0)
#1 Chunk::operator delete(void*) /home/wave/workspace/jdk_master/src/hotspot/share/memory/arena.cpp:207:54 (libjvm.so+0x7e47f4)
#2 Chunk::chop() /home/wave/workspace/jdk_master/src/hotspot/share/memory/arena.cpp:225:5 (libjvm.so+0x7e4994)
#3 Arena::destruct_contents() /home/wave/workspace/jdk_master/src/hotspot/share/memory/arena.cpp:319:11 (libjvm.so+0x7e5274)
#4 Arena::~Arena() /home/wave/workspace/jdk_master/src/hotspot/share/memory/arena.cpp:283:3 (libjvm.so+0x7e52ea)
#5 ResourceArea::~ResourceArea() /home/wave/workspace/jdk_master/src/hotspot/share/memory/resourceArea.hpp:44:7 (libjvm.so+0xae9d18)
#6 Thread::~Thread() /home/wave/workspace/jdk_master/src/hotspot/share/runtime/thread.cpp:449:3 (libjvm.so+0x1e2214a)
#7 JavaThread::~JavaThread() /home/wave/workspace/jdk_master/src/hotspot/share/runtime/thread.cpp:1903:1 (libjvm.so+0x1e27af4)
#8 JavaThread::~JavaThread() /home/wave/workspace/jdk_master/src/hotspot/share/runtime/thread.cpp:1856:27 (libjvm.so+0x1e27b3c)
#9 ThreadsSMRSupport::smr_delete(JavaThread*) /home/wave/workspace/jdk_master/src/hotspot/share/runtime/threadSMR.cpp:1027:3 (libjvm.so+0x1e47408)
#10 JavaThread::smr_delete() /home/wave/workspace/jdk_master/src/hotspot/share/runtime/thread.cpp:208:5 (libjvm.so+0x1e20e73)
#11 jni_DetachCurrentThread /home/wave/workspace/jdk_master/src/hotspot/share/prims/jni.cpp:4173:11 (libjvm.so+0x137ae7a)
#12 JavaMain /home/wave/workspace/jdk_master/src/java.base/share/native/libjli/java.c:560:5 (libjli.so+0x67e9)
Previous read of size 8 at 0x7b1800003ab0 by thread T14:
[failed to restore the stack]
Location is heap block of size 88 at 0x7b1800003a80 allocated by thread T1:
#0 malloc <null> (java+0x421ee7)
#1 os::malloc(unsigned long, MemoryType, NativeCallStack const&) /home/wave/workspace/jdk_master/src/hotspot/share/runtime/os.cpp:714:18 (libjvm.so+0x19d7e62)
#2 AllocateHeap(unsigned long, MemoryType, NativeCallStack const&, AllocFailStrategy::AllocFailEnum) /home/wave/workspace/jdk_master/src/hotspot/share/memory/allocation.cpp:42:21 (libjvm.so+0x7bfc2d)
#3 AllocateHeap(unsigned long, MemoryType, AllocFailStrategy::AllocFailEnum) /home/wave/workspace/jdk_master/src/hotspot/share/memory/allocation.cpp:52:10 (libjvm.so+0x7bfd34)
#4 CHeapObj<(MemoryType)8>::operator new(unsigned long) /home/wave/workspace/jdk_master/src/hotspot/share/memory/allocation.hpp:193:19 (libjvm.so+0x7e6799)
#5 ChunkPool::initialize() /home/wave/workspace/jdk_master/src/hotspot/share/memory/arena.cpp:135 (libjvm.so+0x7e6799)
#6 chunkpool_init() /home/wave/workspace/jdk_master/src/hotspot/share/memory/arena.cpp:154:3 (libjvm.so+0x7e4441)
#7 vm_init_globals() /home/wave/workspace/jdk_master/src/hotspot/share/runtime/init.cpp:102:3 (libjvm.so+0x11c9b6a)
#8 Threads::create_vm(JavaVMInitArgs*, bool*) /home/wave/workspace/jdk_master/src/hotspot/share/runtime/thread.cpp:3846:3 (libjvm.so+0x1e3108c)
#9 JNI_CreateJavaVM_inner(JavaVM_**, void**, void*) /home/wave/workspace/jdk_master/src/hotspot/share/prims/jni.cpp:3852:12 (libjvm.so+0x1379e74)
#10 JNI_CreateJavaVM /home/wave/workspace/jdk_master/src/hotspot/share/prims/jni.cpp:3935:14 (libjvm.so+0x1379d0f)
#11 InitializeJVM /home/wave/workspace/jdk_master/src/java.base/share/native/libjli/java.c:1538:9 (libjli.so+0x6974)
Thread T1 (tid=9728, running) created by main thread at:
#0 pthread_create <null> (java+0x4233d5)
#1 CallJavaMainInNewThread /home/wave/workspace/jdk_master/src/java.base/unix/native/libjli/java_md_solinux.c:754:9 (libjli.so+0xb53f)
Thread T14 (tid=9742, running) created by thread T1 at:
#0 pthread_create <null> (java+0x4233d5)
#1 os::create_thread(Thread*, os::ThreadType, unsigned long) /home/wave/workspace/jdk_master/src/hotspot/os/linux/os_linux.cpp:926:15 (libjvm.so+0x19e4413)
#2 WatcherThread::WatcherThread() /home/wave/workspace/jdk_master/src/hotspot/share/runtime/thread.cpp:1375:7 (libjvm.so+0x1e25399)
#3 WatcherThread::start() /home/wave/workspace/jdk_master/src/hotspot/share/runtime/thread.cpp:1514:9 (libjvm.so+0x1e2598f)
#4 Threads::create_vm(JavaVMInitArgs*, bool*) /home/wave/workspace/jdk_master/src/hotspot/share/runtime/thread.cpp:4105:7 (libjvm.so+0x1e31bb1)
#5 JNI_CreateJavaVM_inner(JavaVM_**, void**, void*) /home/wave/workspace/jdk_master/src/hotspot/share/prims/jni.cpp:3852:12 (libjvm.so+0x1379e74)
#6 JNI_CreateJavaVM /home/wave/workspace/jdk_master/src/hotspot/share/prims/jni.cpp:3935:14 (libjvm.so+0x1379d0f)
#7 InitializeJVM /home/wave/workspace/jdk_master/src/java.base/share/native/libjli/java.c:1538:9 (libjli.so+0x6974)
SUMMARY: ThreadSanitizer: data race /home/wave/workspace/jdk_master/src/hotspot/share/memory/arena.cpp:93:16 in ChunkPool::free(Chunk*)
And the openjdk code is below, you could see there is a ThreadCritical which derives from pthread_mutex and implements lock/unlock in the ctor/dtor:
// Return a chunk to the pool
void free(Chunk* chunk) {
assert(chunk->length() + Chunk::aligned_overhead_size() == _size, "bad size");
ThreadCritical tc;
_num_used--;
// Add chunk to list
chunk->set_next(_first);
92: _first = chunk;
93: _num_chunks++;
}
-----Original Message-----
From: Dmitry Vyukov <dvyukov at google.com>
Sent: Tuesday, February 25, 2020 1:30 PM
To: Jie He <Jie.He at arm.com>
Cc: tsan-dev at openjdk.java.net; nd <nd at arm.com>; thread-sanitizer <thread-sanitizer at googlegroups.com>
Subject: Re: build openjdk with fsanitizer=thread
On Tue, Feb 25, 2020 at 6:20 AM Jie He <Jie.He at arm.com> wrote:
>
> Hi
>
> I built openjdk with enabling fanitizer=thread recently, and got a lot of warning by tsan even a helloworld case.
>
> Then I investigated around more than 15 warnings, found they could be divided into 3 classes:
>
>
> 1. Benign races, commonly, there is a comment to indicate why it is safe in MP.
+thread-sanitizer mailing list
Hi Jie,
C++ standard still calls this data race and renders behavior of the
program as undefined. Comments don't fix bugs ;)
> 2. Runtime atomic implementation, in x86, the atomic load and store will be translated to platformload/store.
I assume here platformload/store are implemented as plain loads and stores. These may need to be changed at least in tsan build (but maybe in all builds, because see the previous point). I am not aware of the openjdk portability requirements, but today the __atomic_load/store_n intrinsics may be a good choice.
> 3. Runtime function implement protected by MutexLocker/ThreadCritical, which finally implemented by pthread_mutex.
>
> For 3, I couldn't understand why tsan couldn't recognize that it's safe and protected by a lock. In TSAN document, it said pthread functions are supported.
> So I tried to add annotation(ANNOTATION_RWCLOCK_ACQUIRED/RELEASED) to mark, then got the warning, double of lock, it seems tsan knows MutexLocker is a lock.
>
> Or because one of the conflicting threads lost its stack, in this kind of warning, there is one out of the two threads fails to restore its stack.
> It may result that tsan only knows the thread calls read/write, but doesn't know the memory operation is protected by a lock.
> These threads couldn't restore the stack are JIT threads/Java threads? I need to fix the tsan symbolizer function first for this situation?
Yes, tsan understands pthread mutex natively, no annotations required.
You may try to increase history_size flag to get the second stack:
https://github.com/google/sanitizers/wiki/ThreadSanitizerFlags
"failed to restore stack trace" should not lead to false positives either.
Please post several full tsan reports and links to the corresponding source code.
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