python - 无法使用 gremlinpython 进行查询

Question

我正在使用 gremlinpython 访问 Janusgraph 中的数据，但它抛出异常，而数据可从 Gremlin shell 访问。

这是我远程运行的 Python 代码:

from gremlin_python import statics
from gremlin_python.structure.graph import Graph
from gremlin_python.process.graph_traversal import __
from gremlin_python.process.strategies import *
from gremlin_python.driver.driver_remote_connection import DriverRemoteConnection

graph = Graph()
g = graph.traversal().withRemote(DriverRemoteConnection('ws://<IP>:8182/gremlin','g', 
username="janusgraph"))
print g.V().has('name', 'saturn').next()

这是我遇到的异常:

Traceback (most recent call last):
  File "test.py", line 10, in <module>
    print g.V().has('name', 'saturn').next()
  File "/root/venv/lib/python2.7/site-packages/gremlin_python/process/traversal.py", line 70, in next
    return self.__next__()
  File "/root/venv/lib/python2.7/site-packages/gremlin_python/process/traversal.py", line 43, in __next__
    self.traversal_strategies.apply_strategies(self)
  File "/root/venv/lib/python2.7/site-packages/gremlin_python/process/traversal.py", line 346, in apply_strategies
    traversal_strategy.apply(traversal)
  File "/root/venv/lib/python2.7/site-packages/gremlin_python/driver/remote_connection.py", line 143, in apply
    remote_traversal = self.remote_connection.submit(traversal.bytecode)
  File "/root/venv/lib/python2.7/site-packages/gremlin_python/driver/driver_remote_connection.py", line 54, in submit
    results = result_set.all().result()
  File "/root/venv/lib/python2.7/site-packages/concurrent/futures/_base.py", line 462, in result
    return self.__get_result()
  File "/root/venv/lib/python2.7/site-packages/concurrent/futures/_base.py", line 414, in __get_result
    raise exception_type, self._exception, self._traceback
KeyError: None

Gremlin shell 的输出:

gremlin> graph = JanusGraphFactory.open('conf/janusgraph-hbase-es.properties')
==>standardjanusgraph[hbase:[slv-01, slv-02, slv-03]]
gremlin> GraphOfTheGodsFactory.load(graph)
==>null
gremlin> g = graph.traversal()
==>graphtraversalsource[standardjanusgraph[hbase:[slv-01, slv-02, slv-03]], standard]
gremlin> saturn = g.V().has('name', 'saturn').next()
==>v[4152]
gremlin> g.V(saturn).valueMap()
==>[name:[saturn],age:[10000]]

Gremlin 服务器的配置文件:

gremlin-server.yaml

host: <IP>
port: 8182
scriptEvaluationTimeout: 30000
channelizer: org.apache.tinkerpop.gremlin.server.channel.WebSocketChannelizer
graphs: {
  graph: conf/gremlin-server/janusgraph-hbase-es.properties
}
plugins:
  - janusgraph.imports
scriptEngines: {
  gremlin-groovy: {
    imports: [java.lang.Math],
    staticImports: [java.lang.Math.PI],
    scripts: [scripts/empty-sample.groovy]}}
serializers:
  - { className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV1d0, config: { ioRegistries: [org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistry] }}
  - { className: org.apache.tinkerpop.gremlin.driver.ser.GryoLiteMessageSerializerV1d0, config: {ioRegistries: [org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistry] }}
  - { className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV1d0, config: { serializeResultToString: true }}
  - { className: org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerGremlinV1d0, config: { ioRegistries: [org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistryV1d0] }}
  - { className: org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerGremlinV2d0, config: { ioRegistries: [org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistry] }}
  - { className: org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerV1d0, config: { ioRegistries: [org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistryV1d0] }}
processors:
  - { className: org.apache.tinkerpop.gremlin.server.op.session.SessionOpProcessor, config: { sessionTimeout: 28800000 }}
  - { className: org.apache.tinkerpop.gremlin.server.op.traversal.TraversalOpProcessor, config: { cacheExpirationTime: 600000, cacheMaxSize: 1000 }}
metrics: {
  consoleReporter: {enabled: true, interval: 180000},
  csvReporter: {enabled: true, interval: 180000, fileName: /tmp/gremlin-server-metrics.csv},
  jmxReporter: {enabled: true},
  slf4jReporter: {enabled: true, interval: 180000},
  gangliaReporter: {enabled: false, interval: 180000, addressingMode: MULTICAST},
  graphiteReporter: {enabled: false, interval: 180000}}
maxInitialLineLength: 4096
maxHeaderSize: 8192
maxChunkSize: 8192
maxContentLength: 65536
maxAccumulationBufferComponents: 1024
resultIterationBatchSize: 64
writeBufferLowWaterMark: 32768
writeBufferHighWaterMark: 65536

janusgraph-hbase-es.properties

# JanusGraph configuration sample: HBase and Elasticsearch
#
# This file connects to HBase using a Zookeeper quorum
# (storage.hostname) consisting solely of localhost.  It also connects
# to Elasticsearch running on localhost over Elasticsearch's native "Transport"
# protocol.  Zookeeper, the HBase services, and Elasticsearch must already 
# be running and available before starting JanusGraph with this file.

# The primary persistence provider used by JanusGraph.  This is required. 
# It should be set one of JanusGraph's built-in shorthand names for its
# standard storage backends (shorthands: berkeleyje, cassandrathrift,
# cassandra, astyanax, embeddedcassandra, cql, hbase, inmemory) or to the
# full package and classname of a custom/third-party StoreManager
# implementation.
#
# Default:    (no default value)
# Data Type:  String
# Mutability: LOCAL

gremlin.graph=org.janusgraph.core.JanusGraphFactory

storage.backend=hbase
storage.hbase.ext.zookeeper.znode.parent=/hbase-unsecure
storage.hbase.table = janusgraph

# The hostname or comma-separated list of hostnames of storage backend
# servers.  This is only applicable to some storage backends, such as
# cassandra and hbase.
#
# Default:    127.0.0.1
# Data Type:  class java.lang.String[]
# Mutability: LOCAL
storage.hostname=slv-01,slv-02,slv-03

# Whether to enable JanusGraph's database-level cache, which is shared
# across all transactions. Enabling this option speeds up traversals by
# holding hot graph elements in memory, but also increases the likelihood
# of reading stale data.  Disabling it forces each transaction to
# independently fetch graph elements from storage before reading/writing
# them.
#
# Default:    false
# Data Type:  Boolean
# Mutability: MASKABLE
cache.db-cache = true

# How long, in milliseconds, database-level cache will keep entries after
# flushing them.  This option is only useful on distributed storage
# backends that are capable of acknowledging writes without necessarily
# making them immediately visible.
#
# Default:    50
# Data Type:  Integer
# Mutability: GLOBAL_OFFLINE
#
# Settings with mutability GLOBAL_OFFLINE are centrally managed in
# JanusGraph's storage backend.  After starting the database for the first
# time, this file's copy of this setting is ignored.  Use JanusGraph's
# Management System to read or modify this value after bootstrapping.
cache.db-cache-clean-wait = 20

# Default expiration time, in milliseconds, for entries in the
# database-level cache. Entries are evicted when they reach this age even
# if the cache has room to spare. Set to 0 to disable expiration (cache
# entries live forever or until memory pressure triggers eviction when set
# to 0).
#
# Default:    10000
# Data Type:  Long
# Mutability: GLOBAL_OFFLINE
#
# Settings with mutability GLOBAL_OFFLINE are centrally managed in
# JanusGraph's storage backend.  After starting the database for the first
# time, this file's copy of this setting is ignored.  Use JanusGraph's
# Management System to read or modify this value after bootstrapping.
cache.db-cache-time = 180000

# Size of JanusGraph's database level cache.  Values between 0 and 1 are
# interpreted as a percentage of VM heap, while larger values are
# interpreted as an absolute size in bytes.
#
# Default:    0.3
# Data Type:  Double
# Mutability: MASKABLE
cache.db-cache-size = 0.5

# The indexing backend used to extend and optimize JanusGraph's query
# functionality. This setting is optional.  JanusGraph can use multiple
# heterogeneous index backends.  Hence, this option can appear more than
# once, so long as the user-defined name between "index" and "backend" is
# unique among appearances.Similar to the storage backend, this should be
# set to one of JanusGraph's built-in shorthand names for its standard
# index backends (shorthands: lucene, elasticsearch, es, solr) or to the
# full package and classname of a custom/third-party IndexProvider
# implementation.
#
# Default:    elasticsearch
# Data Type:  String
# Mutability: GLOBAL_OFFLINE
#
# Settings with mutability GLOBAL_OFFLINE are centrally managed in
# JanusGraph's storage backend.  After starting the database for the first
# time, this file's copy of this setting is ignored.  Use JanusGraph's
# Management System to read or modify this value after bootstrapping.
index.search.backend=elasticsearch

# The hostname or comma-separated list of hostnames of index backend
# servers.  This is only applicable to some index backends, such as
# elasticsearch and solr.
#
# Default:    127.0.0.1
# Data Type:  class java.lang.String[]
# Mutability: MASKABLE
index.search.hostname=<ES IP>:9201
index.search.index-name = search

有人可以帮忙吗？谢谢。

Answer 1

问题出在 gremlinpython 的最新版本 (3.3.3) 上。使用 3.2.6 作为 gremlinpython 的版本将解决这个问题。查看this blog获取使用 Python 连接到 Janusgraph 的完整指南。