Hello,

I'm new to SPDK and am benchmarking RocksDB with BlobFS on an NVMe SSD. 

When I tried to run a fillseq db_bench workload for 500M keys, db_bench gets stuck after processing some 100M keys. After playing with the db_bench options I was using, I found out that it only gets stuck when WAL is enabled. When I disabled WAL, the entire workload completed properly.

With WAL enabled, the issue occurs consistently on each run. Using gdb and some extra print statements, I saw that this happened when RocksDB calls sync on one of the MANIFEST files. The sync call waits on a semaphore in this line,

https://github.com/spdk/spdk/blob/master/lib/blobfs/blobfs.c#L2169

I have not yet properly debugged which is the piece of code that is not calling sem_post, but it looks to be this section (though I'm not quite certain about this),

https://github.com/spdk/spdk/blob/master/lib/blobfs/blobfs.c#L1756

Any ideas what is happening here? Is this a known issue or a bug? (Just to note, the run_tests.sh db_bench test script in the repository runs the fillseq workload with WAL disabled).

Thanks
Swami