Data race in AtomicUnorderedMap::size()

WARNING: ThreadSanitizer: data race (pid=131734)

00:06:47.595   Write of size 8 at 0x7d580002fc50 by thread T19 (mutexes: read M15526, write M20152):

00:06:47.595     #0 std::_Hashtable<unsigned short, std::pair<unsigned short const, SingleThreadedRCPtr<Stream> >, std::allocator<std::pair<unsigned short const, SingleThreadedRCPtr<Stream> > >, std::__detail::_Select1st, std::equal_to<unsigned short>, std::hash<unsigned short>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<false, false, true> >::_M_insert_unique_node(unsigned long, unsigned long, std::__detail::_Hash_node<std::pair<unsigned short const, SingleThreadedRCPtr<Stream> >, false>*) /usr/bin/../lib/gcc/x86_64-linux-gnu/4.9/../../../../include/c++/4.9/bits/hashtable.h:1625 (ep.so+0x000000069fa7)

00:06:47.595     #1 AtomicUnorderedMap<unsigned short, Stream, SingleThreadedRCPtr<Stream>, std::hash<unsigned short>, std::equal_to<unsigned short>, std::allocator<std::pair<unsigned short const, SingleThreadedRCPtr<Stream> > > >::insert(std::pair<unsigned short const, SingleThreadedRCPtr<Stream> > const&) /usr/bin/../lib/gcc/x86_64-linux-gnu/4.9/../../../../include/c++/4.9/bits/hashtable.h:1724 (ep.so+0x0000000613e9)

00:06:47.595     #2 EvpDcpStreamReq(engine_interface*, void const*, unsigned int, unsigned int, unsigned short, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long*, ENGINE_ERROR_CODE (*)(vbucket_failover_t*, unsigned long, void const*)) /home/couchbase/jenkins/workspace/ep-engine-threadsanitizer-master/ep-engine/src/ep_engine.cc:1512 (ep.so+0x0000000b3737)

00:06:47.595     #3 mock_dcp_stream_req(engine_interface*, void const*, unsigned int, unsigned int, unsigned short, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long*, ENGINE_ERROR_CODE (*)(vbucket_failover_t*, unsigned long, void const*)) /home/couchbase/jenkins/workspace/ep-engine-threadsanitizer-master/memcached/programs/engine_testapp/engine_testapp.cc:453 (engine_testapp+0x0000004cf617)

00:06:47.595     #4 TestDcpConsumer::openStreams(engine_interface*, engine_interface_v1*) /home/couchbase/jenkins/workspace/ep-engine-threadsanitizer-master/ep-engine/tests/ep_testsuite_dcp.cc:549 (ep_testsuite_dcp.so+0x00000000b211)

00:06:47.595     #5 TestDcpConsumer::run(engine_interface*, engine_interface_v1*) /home/couchbase/jenkins/workspace/ep-engine-threadsanitizer-master/ep-engine/tests/ep_testsuite_dcp.cc:233 (ep_testsuite_dcp.so+0x000000005ec5)

00:06:47.595     #6 continuous_dcp_thread(void*) /home/couchbase/jenkins/workspace/ep-engine-threadsanitizer-master/ep-engine/tests/ep_testsuite_dcp.cc:851 (ep_testsuite_dcp.so+0x000000038899)

00:06:47.595     #7 platform_thread_wrap(void*) /home/couchbase/jenkins/workspace/ep-engine-threadsanitizer-master/platform/src/cb_pthreads.cc:54 (libplatform.so.0.1.0+0x0000000056fb)

00:06:47.595 

00:06:47.595   Previous read of size 8 at 0x7d580002fc50 by main thread (mutexes: write M14188, write M20259, write M14598):

00:06:47.595     #0 DcpProducer::addStats(void (*)(char const*, unsigned short, char const*, unsigned int, void const*), void const*) /usr/bin/../lib/gcc/x86_64-linux-gnu/4.9/../../../../include/c++/4.9/bits/hashtable.h:500 (ep.so+0x0000000640f4)

00:06:47.595     #1 ConnStatBuilder::operator()(SingleThreadedRCPtr<ConnHandler>&) /home/couchbase/jenkins/workspace/ep-engine-threadsanitizer-master/ep-engine/src/ep_engine.cc:3859 (ep.so+0x0000000e02c1)

00:06:47.595     #2 EventuallyPersistentEngine::doDcpStats(void const*, void (*)(char const*, unsigned short, char const*, unsigned int, void const*)) /home/couchbase/jenkins/workspace/ep-engine-threadsanitizer-master/ep-engine/src/ep_engine.cc:4116 (ep.so+0x0000000bf61a)

00:06:47.595     #3 EventuallyPersistentEngine::getStats(void const*, char const*, int, void (*)(char const*, unsigned short, char const*, unsigned int, void const*)) /home/couchbase/jenkins/workspace/ep-engine-threadsanitizer-master/ep-engine/src/ep_engine.cc:4551 (ep.so+0x0000000c3114)

00:06:47.595     #4 EvpGetStats(engine_interface*, void const*, char const*, int, void (*)(char const*, unsigned short, char const*, unsigned int, void const*)) /home/couchbase/jenkins/workspace/ep-engine-threadsanitizer-master/ep-engine/src/ep_engine.cc:221 (ep.so+0x0000000b27de)

00:06:47.595     #5 std::_Function_handler<ENGINE_ERROR_CODE (), std::_Bind<ENGINE_ERROR_CODE (*(engine_interface*, void const*, char const*, int, void (*)(char const*, unsigned short, char const*, unsigned int, void const*)))(engine_interface*, void const*, char const*, int, void (*)(char const*, unsigned short, char const*, unsigned int, void const*))> >::_M_invoke(std::_Any_data const&) /usr/bin/../lib/gcc/x86_64-linux-gnu/4.9/../../../../include/c++/4.9/functional:1263 (engine_testapp+0x0000004f6f22)

00:06:47.595     #6 std::function<ENGINE_ERROR_CODE ()>::operator()() const /usr/bin/../lib/gcc/x86_64-linux-gnu/4.9/../../../../include/c++/4.9/functional:2439 (engine_testapp+0x0000004ce9a7)

00:06:47.595     #7 get_str_stat(engine_interface*, engine_interface_v1*, char const*, char const*) /home/couchbase/jenkins/workspace/ep-engine-threadsanitizer-master/ep-engine/tests/ep_test_apis.cc:1161 (ep_testsuite_dcp.so+0x0000000486b4)

00:06:47.595     #8 get_int_stat(engine_interface*, engine_interface_v1*, char const*, char const*) /home/couchbase/jenkins/workspace/ep-engine-threadsanitizer-master/ep-engine/tests/ep_test_apis.cc:1136 (ep_testsuite_dcp.so+0x00000004494b)

00:06:47.595     #9 wait_for_stat_to_be(engine_interface*, engine_interface_v1*, char const*, int, char const*, long) /home/couchbase/jenkins/workspace/ep-engine-threadsanitizer-master/ep-engine/tests/ep_test_apis.cc:1336 (ep_testsuite_dcp.so+0x00000004abb2)

00:06:47.595     #10 test_dcp_producer_keep_stream_open(engine_interface*, engine_interface_v1*) /home/couchbase/jenkins/workspace/ep-engine-threadsanitizer-master/ep-engine/tests/ep_testsuite_dcp.cc:1854 (ep_testsuite_dcp.so+0x00000001af62)

00:06:47.595     #11 execute_test(test, char const*, char const*) /home/couchbase/jenkins/workspace/ep-engine-threadsanitizer-master/memcached/programs/engine_testapp/engine_testapp.cc:982 (engine_testapp+0x0000004cc830)

00:06:47.595     #12 __libc_start_main /build/buildd/eglibc-2.15/csu/libc-start.c:226 (libc.so.6+0x00000002176c)

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