Question

我正在使用以下组件运行Web应用程序：

Python 3.5.2
uWSGI 2.0.11.2
cassandra-driver 3.6.0
cassandra 3.7

使用Cassandra集群（3个节点）：

节点1 - IP： 172.17.0.4
节点2 - IP： 172.17.0.5
节点3 - IP： 172.17.0.6

使用配置 NetworkTopologyStrategy 和 GossipingPropertyFileSnitch 。

我已关注uWSGI connection example from cqlengine：

from cqlengine import connection
from cassandra.io.libevreactor import LibevConnection
from cqlengine.connection import (
    cluster as cql_cluster, 
    session as cql_session
)


try:
    from uwsgidecorators import postfork
except ImportError:
    # We're not in a uWSGI context, no need to hook Cassandra session
    # initialization to the postfork event.
    pass
else:
    @postfork
    def cassandra_init():
        """ Initialize a new Cassandra session in the context.

        Ensures that a new session is returned for every new request.
        """
        if cql_cluster is not None:
            cql_cluster.shutdown()
        if cql_session is not None:
            cql_session.shutdown()

        connection.setup(
            ['172.0.4'],
            'my_keyspace',
            port=9042,
            connection_class=LibevConnection
        )

但我收到错误＆＃34; 无法为新主机x.x.x.x创建连接池＆＃34;在所有cassandra节点上（ 172.17.0.4 ， 172.17.0.5 和 172.17.0.6 ）：

Respawned uWSGI worker 2 (new pid: 90)
mapping worker 2 to CPUs: 3 4 5
2016-09-14 21:00:47,434 WARNI [cassandra.cluster][Thread-2] Failed to create connection pool for new host 172.17.0.4:
Traceback (most recent call last):
    File "cassandra/cluster.py", line 2232, in cassandra.cluster.Session.add_or_renew_pool.run_add_or_renew_pool (cassandra/cluster.c:38826)
    File "cassandra/pool.py", line 328, in cassandra.pool.HostConnection.__init__ (cassandra/pool.c:6243)
    File "cassandra/cluster.py", line 1107, in cassandra.cluster.Cluster.connection_factory (cassandra/cluster.c:14943)
    File "cassandra/connection.py", line 330, in cassandra.connection.Connection.factory (cassandra/connection.c:5766)
cassandra.OperationTimedOut: errors=Timed out creating connection (5 seconds), last_host=None
2016-09-14 21:00:47,437 WARNI [cassandra.cluster][Thread-1] Failed to create connection pool for new host 172.17.0.6:
Traceback (most recent call last):
    File "cassandra/cluster.py", line 2232, in cassandra.cluster.Session.add_or_renew_pool.run_add_or_renew_pool (cassandra/cluster.c:38826)
    File "cassandra/pool.py", line 328, in cassandra.pool.HostConnection.__init__ (cassandra/pool.c:6243)
    File "cassandra/cluster.py", line 1107, in cassandra.cluster.Cluster.connection_factory (cassandra/cluster.c:14943)
    File "cassandra/connection.py", line 330, in cassandra.connection.Connection.factory (cassandra/connection.c:5766)
cassandra.OperationTimedOut: errors=Timed out creating connection (5 seconds), last_host=None
...The work of process 19 is done. Seeya!
worker 7 killed successfully (pid: 19)

根据日志，它能够连接到节点但由于某种原因它接缝断开并抛出以前的错误：

2016-09-15 23:23:03,786 DEBUG [cassandra.pool][Thread-2] Initializing connection for host 172.17.0.4
2016-09-15 23:23:03,787 DEBUG [cassandra.connection][Thread-2] Not sending options message for new connection(139905425534704) to 172.17.0.4 because compression is disabled and a cql version was not specified
2016-09-15 23:23:03,787 DEBUG [cassandra.connection][Thread-2] Sending StartupMessage on <LibevConnection(139905425534704) 172.17.0.4:9042>
2016-09-15 23:23:03,787 DEBUG [cassandra.connection][Thread-2] Sent StartupMessage on <LibevConnection(139905425534704) 172.17.0.4:9042>
2016-09-15 23:23:03,788 DEBUG [cassandra.connection][event_loop] Got ReadyMessage on new connection (139905425534704) from 172.17.0.4
2016-09-15 23:23:03,788 DEBUG [cassandra.pool][Thread-2] Finished initializing connection for host 172.17.0.4
2016-09-15 23:23:03,788 DEBUG [cassandra.cluster][Thread-2] Added pool for host 172.17.0.4 to session
2016-09-15 22:24:29,239 DEBUG [cassandra.io.libevreactor][Thread-2] Closing connection (139945376028152) to 172.17.0.4
2016-09-15 22:24:29,240 DEBUG [cassandra.io.libevreactor][Thread-2] Closed socket to 172.17.0.4
2016-09-15 22:24:29,240 DEBUG [cassandra.connection][Thread-2] Connection to 172.17.0.4 was closed during the startup handshake
2016-09-15 22:24:29,242 WARNI [cassandra.cluster][Thread-2] Failed to create connection pool for new host 172.17.0.4:

已编辑（已添加有关此问题的更多调试信息）

该应用可以ping通端口9042上的任何节点，因此它不是连接问题。如果我运行nodetool status，集群中的三个节点似乎没问题：

--  Address     Load       Tokens       Owns (effective)  Host ID                               Rack
UN  172.17.0.5  111.72 KiB  256          67.3%             fdd4740d-1ce5-4deb-9a3e-5c18c80ee63e  rack1
UN  172.17.0.4  98.96 KiB  256          66.8%             4fe5a60c-2b6a-4d57-ab6a-e4176ce69b68  rack1
UN  172.17.0.6  94.67 KiB  256          66.0%             5e2675e3-c2a7-4af1-80f0-4cb9573ecf2b  rack1

我尝试过使用Cassandra 3.7 和 2.2.7 ，但结果相同。但是，如果我尝试使用 Node1 运行应用程序，它就可以运行！

Cassandra节点中的日志显示以下内容：

INFO  22:14:33 Unexpected exception during request; channel = [id: 0xd6d3c9ae, L:/172.17.0.6:9042 ! R:/172.17.0.5:42944]
io.netty.channel.unix.Errors$NativeIoException: syscall:read(...)() failed: Connection reset by peer
INFO  22:16:26 Unexpected exception during request; channel = [id: 0x2cfa996f, L:/172.17.0.6:9042 - R:/172.17.0.5:42954]
io.netty.channel.unix.Errors$NativeIoException: syscall:read(...)() failed: Connection reset by peer
INFO  22:54:13 Unexpected exception during request; channel = [id: 0x4134ec0f, L:/172.17.0.6:9042 ! R:/172.17.0.5:42992]

有人知道这里发生了什么吗？任何帮助将不胜感激。

Answer 1

请注意，ping实际上不是TCP，因此您可能还希望使用nc -nz <ip> 9042来验证TCP。但是，由于您正在获得超时而不是“连接被拒绝”，我将认为它不是连接。

您应该检查的主要事项是您的uWSGI配置是否启用了任何类型的猴子修补（例如，gevent）。示例中使用的libevreactor使用标准库并假定没有修补。

我认为您可以通过禁用修补或删除显式connection_class参数来解决此问题，在这种情况下，驱动程序将检测修补并相应地默认反应器实现。

Cassandra无法为新主机创建连接池

1 个答案: