RocksIOError during bulk_search

[tolot27]

I have configured my rocksdb.yaml with nproc: 4' as shown in the example config at step 2 of https//bigsi.readme.io/docs/your-first-bigsi. If I do a bulk_searchI run intoRocksIOError`. The stack trace is:

multiprocessing.pool.RemoteTraceback: 
"""
Traceback (most recent call last):
  File "/usr/lib/python3.6/multiprocessing/pool.py", line 119, in worker
    result = (True, func(*args, **kwds))
  File "/usr/lib/python3.6/multiprocessing/pool.py", line 44, in mapstar
    return list(map(*args))
  File "/usr/local/lib/python3.6/dist-packages/bigsi/__main__.py", line 76, in search_bigsi_parallel
    bigsi = BIGSI(l[0][0])
  File "/usr/local/lib/python3.6/dist-packages/bigsi/graph/bigsi.py", line 134, in __init__
    self.storage = get_storage(config)
  File "/usr/local/lib/python3.6/dist-packages/bigsi/storage/__init__.py", line 19, in get_storage
    return STORAGE_DICT[config["storage-engine"]](config["storage-config"])
  File "/usr/local/lib/python3.6/dist-packages/bigsi/storage/rocksdb.py", line 49, in __init__
    read_only=self.storage_config.get("read_only", False),
  File "rocksdb/_rocksdb.pyx", line 1636, in rocksdb._rocksdb.DB.__cinit__
  File "rocksdb/_rocksdb.pyx", line 85, in rocksdb._rocksdb.check_status
rocksdb.errors.RocksIOError: b'IO error: While lock file: bigsi.rocks/LOCK: Resource temporarily unavailable'
"""

If I lower nproc to one, the error is gone, obviously. It looks like search_bigsi_parallel is the entry point to fix this error.