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mohankishore / python_dynamodb_lock

Python package that emulates the dynamodb-lock-client java library from awslabs
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expiry_period does not expire locks #2793

Open malcolmtank opened 4 weeks ago

malcolmtank commented 4 weeks ago

Description

I'm trying to auto-delete locks after server crashes. To accomplish this, I set a relatively short expiry_period. After crashes, long after the expiry_time reported by dynamodb, I still see lock acquisition timeouts.

What I Did

I have tried to acquire expired locks and observed lock acquisition timeouts. I would like to make a change like the following to acquire_lock:

# if the record_version_number has not changed for more than _lease_duration period,
# it basically means that the owner thread/process has died.
now = time.monotonic()
last_version_elapsed_time = now - last_version_fetch_time
if last_version_elapsed_time > existing_lock.lease_duration or now > existing_lock.expiry_time:  # key change here
    logger.warning('Existing lock\'s lease has expired: %s', str(existing_lock))
    self._overwrite_existing_lock_in_dynamodb(new_lock, last_record_version_number)
    logger.debug('Added to the DDB. Adding to in-memory map: %s', new_lock.unique_identifier)
    new_lock.status = DynamoDBLock.LOCKED
    self._locks[new_lock.unique_identifier] = new_lock
    logger.info('Successfully updated with the new lock: %s', str(new_lock))
    return new_lock