Exception while handling packet

[xoriole]

ERROR   1523354803.66       community:299   Exception occurred while handling packet!
Traceback (most recent call last):
  File "/home/sandip/tudelft/tribler/Tribler/pyipv8/ipv8/deprecated/community.py", line 296, in on_packet
    self.decode_map[data[22]](source_address, data)
  File "/home/sandip/tudelft/tribler/Tribler/pyipv8/ipv8/attestation/trustchain/community.py", line 33, in wrapper
    return f(self, *args, **kwargs)
  File "/home/sandip/tudelft/tribler/Tribler/pyipv8/ipv8/attestation/trustchain/community.py", line 168, in received_half_block
    self.process_half_block(block, peer)
  File "/home/sandip/tudelft/tribler/Tribler/pyipv8/ipv8/attestation/trustchain/community.py", line 33, in wrapper
    return f(self, *args, **kwargs)
  File "/home/sandip/tudelft/tribler/Tribler/pyipv8/ipv8/attestation/trustchain/community.py", line 227, in process_half_block
    validation = self.validate_persist_block(blk)
  File "/home/sandip/tudelft/tribler/Tribler/pyipv8/ipv8/attestation/trustchain/community.py", line 211, in validate_persist_block
    validation = block.validate(self.persistence)
  File "/home/sandip/tudelft/tribler/Tribler/pyipv8/ipv8/attestation/trustchain/block.py", line 156, in validate
    blk = database.get(self.public_key, self.sequence_number)
  File "/home/sandip/tudelft/tribler/Tribler/pyipv8/ipv8/attestation/trustchain/database.py", line 63, in get
    return self._get(u"WHERE public_key = ? AND sequence_number = ?", (buffer(public_key), sequence_number))
  File "/home/sandip/tudelft/tribler/Tribler/pyipv8/ipv8/attestation/trustchain/database.py", line 49, in _get
    db_result = list(self.execute(self.get_sql_header() + query, params, fetch_all=False))
  File "/home/sandip/tudelft/tribler/Tribler/pyipv8/ipv8/database.py", line 40, in wrapper
    return f(self, *args, **kwargs)
  File "/home/sandip/tudelft/tribler/Tribler/pyipv8/ipv8/database.py", line 302, in execute
    result = self._cursor.execute(statement, bindings)
AttributeError: 'NoneType' object has no attribute 'execute'

[qstokkink]

The cursor does not exist. This probably happens while shutting down. Is this correct @xoriole ?

[qstokkink]

It seems this line:

py-ipv8/ipv8/attestation/trustchain/community.py

Lines 399 to 400 in 6c4f728

	# Close the persistence layer
	self.persistence.close()

Should be executed after the parent (superclass) is unloaded, instead of before the super is unloaded.

[xoriole]

@qstokkink yes, correct, it happens during shutdown.

...
Should be executed after the parent (superclass) is unloaded, instead of before the super is unloaded.

seems right.