placeholder_db_name's content is garbled, ObjectId::Invalid: 'Infinity' is an invalid ObjectId

[aimailei]

After a period of normal execution, the following error occurs:

MongoDB Input threw an exception, restarting: exception=>#<BSON::ObjectId::Invalid: 'Infinity' is an invalid ObjectID.>

placeholder_db_name's content like this:

..............@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@1^A^C9=logstash_si!^A^C9^Glogstash_since_Message^?^@^@^@^@^@^@

Anyone else get this exception??
Please help.