MongoDB 3.2 was recently released with WiredTiger as the default storage engine.

In just over five years, MongoDB has evolved into a popular database. MongoDB 3.0 supported “pluggable storage engines.” The B-Tree-based WiredTiger should outperform IO-optimized RocksDB and PerconaFT in in-memory workloads, but it demonstrates performance degradation when we move into IO workloads.

There are reports that WiredTiger 3.2 comes with improved performance, so I ran a quick benchmark against WiredTiger 3.0.

My interest is not only in the absolute performance, but also how it performs during checkpointing. In my previous test we saw periodic drops: https://www.percona.com/blog/2015/07/14/mongodb-benchmark-sysbench-mongodb-io-bound-workload-comparison/.

For this test I am using iiBench by Mark Callaghan: https://github.com/mdcallag/iibench-mongodb.

WiredTiger command line:

numactl --interleave=all ./mongod --dbpath=/mnt/i3600/mongo/ --storageEngine=wiredTiger --syncdelay=900 --wiredTigerCacheSizeGB=10 --wiredTigerJournalCompressor=none

Storage: Intel SSD DC P3600 SSD 1.6TB
Server: Bare Metal powered by Intel(R) Xeon(R) CPU E5-2680

For workload, I inserted 200 million records with 1 index.

The results:

WiredTiger 3.2 is indeed faster. It finished in 31 min (compared to 51 min for WiredTiger 3.0).

However, the performance stalls are still there. There are periods of one minute or longer when WiredTiger refuses to process data.