Crash seen in phosphor::ChunkLock::lockMaster (this=0x7ffb264e12e0) at .../phosphor/src/chunk_lock.cc:72

Core was generated by `/opt/couchbase/bin/memcached -C /opt/couchbase/var/lib/couchbase/config/memcach'.

 #0  0x00007ffb2f0b1c99 in compare_exchange_weak (__f=<optimized out>, __s=std::memory_order_seq_cst, __i=phosphor::ChunkLock::MasterLocked, __e=<synthetic pointer>, this=0x7ffb264e12e0) at /usr/local/include/c++/7.3.0/atomic:291

 291						 true, __s, __f);

 #0  0x00007ffb2f0b1c99 in compare_exchange_weak (__f=<optimized out>, __s=std::memory_order_seq_cst, __i=phosphor::ChunkLock::MasterLocked, __e=<synthetic pointer>, this=0x7ffb264e12e0) at /usr/local/include/c++/7.3.0/atomic:291

 #1  compare_exchange_weak (__m=std::memory_order_seq_cst, __i=phosphor::ChunkLock::MasterLocked, __e=<synthetic pointer>, this=0x7ffb264e12e0) at /usr/local/include/c++/7.3.0/atomic:308

 #2  phosphor::ChunkLock::lockMaster (this=0x7ffb264e12e0) at /home/couchbase/jenkins/workspace/couchbase-server-unix/phosphor/src/chunk_lock.cc:72

 #3  0x00007ffb2f0b1d05 in phosphor::MasterChunkLock::lock (this=<optimized out>) at /home/couchbase/jenkins/workspace/couchbase-server-unix/phosphor/src/chunk_lock.cc:105

 #4  0x00007ffb2f0b907c in phosphor::TraceLog::evictThreads (this=this@entry=0x7ffb2f2c4620 <phosphor::TraceLog::getInstance()::log_instance>, lh=...) at /home/couchbase/jenkins/workspace/couchbase-server-unix/phosphor/src/trace_log.cc:309

 #5  0x00007ffb2f0b90ea in phosphor::TraceLog::stop (this=0x7ffb2f2c4620 <phosphor::TraceLog::getInstance()::log_instance>, lh=..., shutdown=<optimized out>) at /home/couchbase/jenkins/workspace/couchbase-server-unix/phosphor/src/trace_log.cc:93

 #6  0x00007ffb2f0b917e in phosphor::TraceLog::stop (this=0x7ffb2f2c4620 <phosphor::TraceLog::getInstance()::log_instance>, shutdown=shutdown@entry=false) at /home/couchbase/jenkins/workspace/couchbase-server-unix/phosphor/src/trace_log.cc:70

 #7  0x00000000004938b7 in deinitializeTracing () at /home/couchbase/jenkins/workspace/couchbase-server-unix/kv_engine/daemon/tracing.cc:107

 #8  0x0000000000449734 in memcached_main (argc=<optimized out>, argv=<optimized out>) at /home/couchbase/jenkins/workspace/couchbase-server-unix/kv_engine/daemon/memcached.cc:1566

 #9  0x00007ffb2c763555 in __libc_start_main () from /lib64/libc.so.6

 #10 0x00000000004418d5 in _start ()