bench tool: write latency overflow issue when enable latency

[Lin,Xiang]

numactl --cpunodebind=0 --membind=0 ./bench -latency=1 -populate=1 -value_size=4096 -threads=128 -time=10 -path=/mnt/pmem0/kvdk -num=26163299 -space=536870912000 -max_write_threads=128 -fill=1 -type=string > ./results/string_vs4096_fill_thread128
Write latency overflow: 10266872 us
sh: line 1: 45103 Segmentation fault (core dumped) numactl --cpunodebind=0 --membind=0 ./bench -latency=1 -populate=1 -value_size=4096 -threads=128 -time=10 -path=/mnt/pmem0/kvdk -num=26163299 -space=536870912000 -max_write_threads=128 -fill=1 -type=string > ./results/string_vs4096_fill_thread128
EMON collector successfully stopped.
Read string-type kv
EMON collector successfully stopped.
Insert new string-type kv
EMON collector successfully stopped.
Batch write string-type kv
EMON collector successfully stopped.
Update string-type kv
EMON collector successfully stopped.
Mixed read/update string-type kv
EMON collector successfully stopped.
Fill string-type kv
numactl --cpunodebind=0 --membind=0 ./bench -latency=1 -populate=1 -value_size=4096 -threads=256 -time=10 -path=/mnt/pmem0/kvdk -num=26163299 -space=536870912000 -max_write_threads=256 -fill=1 -type=string > ./results/string_vs4096_fill_thread256
Write latency overflow: 10097061 us
sh: line 1: 46877 Segmentation fault (core dumped) numactl --cpunodebind=0 --membind=0 ./bench -latency=1 -populate=1 -value_size=4096 -threads=256 -time=10 -path=/mnt/pmem0/kvdk -num=26163299 -space=536870912000 -max_write_threads=256 -fill=1 -type=string > ./results/string_vs4096_fill_thread256
EMON collector successfully stopped.
Read string-type kv
EMON collector successfully stopped.
Insert new string-type kv
Write latency overflow: 11150634 us
sh: line 1: 47928 Segmentation fault (core dumped) numactl --cpunodebind=0 --membind=0 ./bench -latency=1 -populate=1 -value_size=4096 -threads=256 -time=10 -path=/mnt/pmem0/kvdk -num=26163299 -space=536870912000 -max_write_threads=256 -fill=0 -type=string -read_ratio=0 -existing_keys_ratio=0 > ./results/string_vs4096_insert_thread256
EMON collector successfully stopped.
Batch write string-type kv
EMON collector successfully stopped.
Update string-type kv
Write latency overflow: 11173244 us
sh: line 1: 48963 Segmentation fault (core dumped) numactl --cpunodebind=0 --membind=0 ./bench -latency=1 -populate=1 -value_size=4096 -threads=256 -time=10 -path=/mnt/pmem0/kvdk -num=26163299 -space=536870912000 -max_write_threads=256 -fill=0 -type=string -read_ratio=0 > ./results/string_vs4096_update_thread256
EMON collector successfully stopped.
Mixed read/update string-type kv
EMON collector successfully stopped.