Neo4j python API 在多个查询中崩溃

Question

我正在尝试使用 neo4j docker 图像从 neo4j python API 创建边缘。基本上我启动以下脚本：

from neo4j import GraphDatabase
server='bolt://localhost:7687'
usr="neo4j"
pwd="jdl"

driver = GraphDatabase.driver(server, auth=(usr, pwd))
for line in tqdm.tqdm(big_mat[0:1000]):
        query_line=f"""MATCH (s:Sample)-[r]->(m:Mineral)
        WHERE s.id='{line[0]}' AND m.name='{line[2]}'
        SET r.amount_weighted={line[1]}
        """
        driver.session().run(query_line)

并且出于某种原因它进行了一系列迭代（在大约 70 到 100 之间变化）然后崩溃并输出这个我无法真正理解的错误..

---------------------------------------------------------------------------
ClientError                               Traceback (most recent call last)
Input In [257], in <cell line: 6>()
      6 for line in tqdm.tqdm(big_mat[0:1000]):
      7         query_line=f"""MATCH (s:Sample)-[r]->(m:Mineral)
      8         WHERE s.id='{line[0]}' AND m.name='{line[2]}'
      9         SET r.amount_weighted={line[1]}
     10         """
---> 11         driver.session().run(query_line)

File ~/anaconda3/envs/Jdl_geochemical/lib/python3.9/site-packages/neo4j/work/simple.py:204, in Session.run(self, query, parameters, **kwparameters)
    201     self._autoResult._buffer_all()  # This will buffer upp all records for the previous auto-transaction
    203 if not self._connection:
--> 204     self._connect(self._config.default_access_mode)
    205 cx = self._connection
    206 protocol_version = cx.PROTOCOL_VERSION

File ~/anaconda3/envs/Jdl_geochemical/lib/python3.9/site-packages/neo4j/work/simple.py:108, in Session._connect(self, access_mode)
    106 if access_mode is None:
    107     access_mode = self._config.default_access_mode
--> 108 super()._connect(access_mode)

File ~/anaconda3/envs/Jdl_geochemical/lib/python3.9/site-packages/neo4j/work/__init__.py:79, in Workspace._connect(self, access_mode)
     66     else:
     67         # This is the first time we open a connection to a server in a
     68         # cluster environment for this session without explicitly
   (...)
     71         # we shall use this database explicitly for all subsequent
     72         # actions within this session.
     73         self._pool.update_routing_table(
     74             database=self._config.database,
     75             imp_user=self._config.impersonated_user,
     76             bookmarks=self._bookmarks,
     77             database_callback=self._set_cached_database
     78         )
---> 79 self._connection = self._pool.acquire(
     80     access_mode=access_mode,
     81     timeout=self._config.connection_acquisition_timeout,
     82     database=self._config.database,
     83     bookmarks=self._bookmarks
     84 )
     85 self._connection_access_mode = access_mode

File ~/anaconda3/envs/Jdl_geochemical/lib/python3.9/site-packages/neo4j/io/__init__.py:842, in BoltPool.acquire(self, access_mode, timeout, database, bookmarks)
    840 def acquire(self, access_mode=None, timeout=None, database=None, bookmarks=None):
    841     # The access_mode and database is not needed for a direct connection, its just there for consistency.
--> 842     return self._acquire(self.address, timeout)

File ~/anaconda3/envs/Jdl_geochemical/lib/python3.9/site-packages/neo4j/io/__init__.py:715, in IOPool._acquire(self, address, timeout)
    710     # if timed out, then we throw error. This time
    711     # computation is needed, as with python 2.7, we
    712     # cannot tell if the condition is notified or
    713     # timed out when we come to this line
    714     if not time_remaining():
--> 715         raise ClientError("Failed to obtain a connection from pool "
    716                           "within {!r}s".format(timeout))
    717 else:
    718     raise ClientError("Failed to obtain a connection from pool "
    719                       "within {!r}s".format(timeout))

ClientError: {code: None} {message: None}

我是否尝试以错误的方式上传边缘？

编辑：

我发现在 for 循环之外定义会话查询成功结束。在大多数示例中，我找到了运行查询的前一种形式，所以也许看到这个可以帮助某人。

from neo4j import GraphDatabase
server='bolt://localhost:7687'
usr="neo4j"
pwd="jdl"

driver = GraphDatabase.driver(server, auth=(usr, pwd))
session=driver.session()
for line in tqdm.tqdm(big_mat[0:1000]):
        query_line=f"""MATCH (s:Sample)-[r]->(m:Mineral)
        WHERE s.id='{line[0]}' AND m.name='{line[2]}'
        SET r.amount_weighted={line[1]}
        """
        session.run(query_line)

Answer 1

问题是会话，就像驱动程序一样，有一个你必须管理的生命周期，就像 opening 文件一样。如果你打开一个驱动程序，你必须在之后关闭它。会话也是如此。

您的代码可能如下所示

from neo4j import GraphDatabase


uri = "neo4j://localhost:7687"
user = "neo4j"
password = "jdl"

driver = GraphDatabase.driver(uri, auth=(user, password))
try:
    for line in tqdm.tqdm(big_mat[0:1000]):
        query_line = f"""MATCH (s:Sample)-[r]->(m:Mineral)
        WHERE s.id='{line[0]}' AND m.name='{line[2]}'
        SET r.amount_weighted={line[1]}
        """
        session = driver.session()
        try:
            session.run(query_line)
        finally:
            session.close()
finally:
    driver.close()

或更整洁：

...

with GraphDatabase.driver(uri, auth=(user, password)) as driver:
    for line in tqdm.tqdm(big_mat[0:1000]):
        query_line = ...
        with driver.session() as session:
            session.run(query_line)

更 in-depth 级别：打开一个会话并在其上执行工作将使它从驱动程序为您维护的连接池中借用一个连接。如果你一直打开会话而不关闭它们，你会在某个时候耗尽池，因为每个会话最多只能保持一个连接。然后，下一个从池中请求连接的会话将超时。

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