Adding a close() method

This a request that came up many times on the old pyrocksdb repo, but was never implemented. The reasoning seemed off to me. Without a close() method, there really is no way to guarantee a lock is released as Python’s garbage collection can’t fully be relied on for this.

If you’re consistently recreating databases from scratch (as I am in my use-case), this really complicates things. Any chance such a method can be added?

[ask]

I’d say this is a pretty important issue for anybody who require graceful shutdown of processes. Relying on del is a horrible practice that should be avoided if possible, and IMHO if necessary even warrants a backward incompatible change.

Doing del(self._db) may work for that specific application, but in general you’d have to carefully del() any other references to the object as well, and who knows what happens if there are circular references.

NOTE: Using a weakref callback you could possibly set a flag to ensure the database was closed (well, implicitly by side effect of being garbage collected, trying to be an optimist here:) pseudocode:

class RocksDBWrapper:
    _db_collected = False

    def open(self):
        self._db = rocksdb.DB(...)
        self._dbref = weakref.ref(self._db, self._on_db_collected)
       
    def _on_db_collected(self, ref):
        self._db_collected = True

    def close(self):
        while not self._db_collected:
            try:
                del(self.db)
            except AttributeError:
                pass
            gc.collect()

I think this is a pretty serious issue that needs to be resolved. Hopefully I, or someone else get some time to look into it.

[twmht]

closed due to fix by #40