ep-engine: data race on Flusher::taskId / Flusher::_state

      WARNING: ThreadSanitizer: data race (pid=13527)

        Write of size 8 at 0x7d4400009650 by thread T14 (mutexes: write M5523):

          #0 Flusher::step(GlobalTask*) couchbase/ep-engine/src/flusher.cc:200 (ep.so+0x0000000e78ae)

          #1 FlusherTask::run() couchbase/ep-engine/src/tasks.cc:61 (ep.so+0x0000001202e2)

          #2 ExecutorThread::run() couchbase/ep-engine/src/executorthread.cc:124 (ep.so+0x0000000e2e05)

          #3 launch_executor_thread(void*) couchbase/ep-engine/src/executorthread.cc:34 (ep.so+0x0000000e28b9)

          #4 platform_thread_wrap .ccache/tmp/cb_pthread.tmp.7e5bc917ff0e.45579.i:0 (libplatform.so.0.1.0+0x000000003891)

        Previous read of size 8 at 0x7d4400009650 by main thread:

          #0 Flusher::wait() couchbase/ep-engine/src/flusher.cc:41 (ep.so+0x0000000e66cf)

          #1 EventuallyPersistentStore::~EventuallyPersistentStore() couchbase/ep-engine/src/ep.cc:514 (ep.so+0x000000071386)

          #2 EventuallyPersistentEngine::~EventuallyPersistentEngine() couchbase/ep-engine/src/ep_engine.cc:6201 (ep.so+0x0000000bfeea)

          #3 EvpDestroy(engine_interface*, bool) couchbase/ep-engine/src/ep_engine.cc:141 (ep.so+0x0000000a0e9c)

          #4 mock_destroy(engine_interface*, bool) couchbase/memcached/programs/engine_testapp/engine_testapp.cc:98 (engine_testapp+0x0000000c4b87)

          #5 execute_test(test, char const*, char const*) couchbase/memcached/programs/engine_testapp/engine_testapp.cc:995 (engine_testapp+0x0000000c4076)

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

WARNING: ThreadSanitizer: data race (pid=10664)

          Read of size 4 at 0x7d4400009888 by main thread (mutexes: write M18321):

            #0 Flusher::stateName() const /home/vagrant/couchbase-server/ep-engine/src/flusher.cc:119 (ep.so+0x0000001fc22e)

            #1 EventuallyPersistentEngine::doEngineStats(void const*, void (*)(char const*, unsigned short, char const*, unsigned int, void const*)) /home/vagrant/couchbase-server/ep-engine/src/ep_engine.cc:3025 (ep.so+0x000000180649)

            #2 EventuallyPersistentEngine::getStats(void const*, char const*, int, void (*)(char const*, unsigned short, char const*, unsigned int, void const*)) /home/vagrant/couchbase-server/ep-engine/src/ep_engine.cc:4374 (ep.so+0x00000018d960)

            #3 EvpGetStats(engine_interface*, void const*, char const*, int, void (*)(char const*, unsigned short, char const*, unsigned int, void const*)) /home/vagrant/couchbase-server/ep-engine/src/ep_engine.cc:214 (ep.so+0x000000174062)

            #4 mock_get_stats /home/vagrant/couchbase-server/memcached/programs/engine_testapp/engine_testapp.c:196 (exe+0x0000000a741d)

            #5 get_int_stat(engine_interface*, engine_interface_v1*, char const*, char const*) /home/vagrant/couchbase-server/ep-engine/tests/ep_test_apis.cc:799 (ep_testsuite.so+0x0000000dae46)

            #6 verify_curr_items(engine_interface*, engine_interface_v1*, int, char const*) /home/vagrant/couchbase-server/ep-engine/tests/ep_test_apis.cc:834 (ep_testsuite.so+0x0000000e1d31)

            #7 test_dcp_producer_stream_req_disk(engine_interface*, engine_interface_v1*) /home/vagrant/couchbase-server/ep-engine/tests/ep_testsuite.cc:3589 (ep_testsuite.so+0x000000094c9a)

            #8 execute_test /home/vagrant/couchbase-server/memcached/programs/engine_testapp/engine_testapp.c:1055 (exe+0x0000000a3e83)

            #9 main /home/vagrant/couchbase-server/memcached/programs/engine_testapp/engine_testapp.c:1313 (exe+0x0000000a1d84)

          Previous write of size 4 at 0x7d4400009888 by thread T5:

            #0 Flusher::transition_state(flusher_state) /home/vagrant/couchbase-server/ep-engine/src/flusher.cc:114 (ep.so+0x0000001fb7df)

            #1 Flusher::step(GlobalTask*) /home/vagrant/couchbase-server/ep-engine/src/flusher.cc:167 (ep.so+0x0000001fc9d1)

            #2 FlusherTask::run() /home/vagrant/couchbase-server/ep-engine/src/tasks.cc:44 (ep.so+0x00000027870e)

            #3 ExecutorThread::run() /home/vagrant/couchbase-server/ep-engine/src/executorthread.cc:110 (ep.so+0x0000002160ff)

            #4 launch_executor_thread(void*) /home/vagrant/couchbase-server/ep-engine/src/executorthread.cc:34 (ep.so+0x00000021560a)

            #5 platform_thread_wrap /home/vagrant/couchbase-server/platform/src/cb_pthreads.c:19 (libplatform.so.0.1.0+0x0000000033f4)