ruby - 每行有大量列的Cassandra

Question

我在干净的 AWS 实例中使用默认配置设置 cassandra，并将 10000 列插入一行，每列有 1MB 数据。我使用这个 ruby​​(版本 1.9.3)脚本:

10000.times do
    key = rand(36**8).to_s(36)
    value = rand(36**1024).to_s(36) * 1024
    Cas_client.insert(TestColumnFamily,TestRow,{key=>value})
end

每次我运行这个脚本，它都会崩溃:

/usr/local/lib/ruby/gems/1.9.1/gems/thrift-0.8.0/lib/thrift/transport/socket.rb:109:in `read': CassandraThrift::Cassandra::Client::TransportException        from /usr/local/lib/ruby/gems/1.9.1/gems/thrift-0.8.0/lib/thrift/transport/base_transport.rb:87:in `read_all'
    from /usr/local/lib/ruby/gems/1.9.1/gems/thrift-0.8.0/lib/thrift/transport/framed_transport.rb:104:in `read_frame'
    from /usr/local/lib/ruby/gems/1.9.1/gems/thrift-0.8.0/lib/thrift/transport/framed_transport.rb:69:in `read_into_buffer'
    from /usr/local/lib/ruby/gems/1.9.1/gems/thrift-0.8.0/lib/thrift/client.rb:45:in `read_message_begin'
    from /usr/local/lib/ruby/gems/1.9.1/gems/thrift-0.8.0/lib/thrift/client.rb:45:in `receive_message'
    from /usr/local/lib/ruby/gems/1.9.1/gems/cassandra-0.15.0/vendor/0.8/gen-rb/cassandra.rb:251:in `recv_batch_mutate'
    from /usr/local/lib/ruby/gems/1.9.1/gems/cassandra-0.15.0/vendor/0.8/gen-rb/cassandra.rb:243:in `batch_mutate'
    from /usr/local/lib/ruby/gems/1.9.1/gems/thrift_client-0.8.1/lib/thrift_client/abstract_thrift_client.rb:150:in `handled_proxy'        from /usr/local/lib/ruby/gems/1.9.1/gems/thrift_client-0.8.1/lib/thrift_client/abstract_thrift_client.rb:60:in `batch_mutate'
    from /usr/local/lib/ruby/gems/1.9.1/gems/cassandra-0.15.0/lib/cassandra/protocol.rb:7:in `_mutate'
    from /usr/local/lib/ruby/gems/1.9.1/gems/cassandra-0.15.0/lib/cassandra/cassandra.rb:463:in `insert'
    from a.rb:6:in `block in <main>'
    from a.rb:3:in `times'
    from a.rb:3:in `<main>'

但 cassandra 执行正常，然后我运行另一个 ruby​​ 脚本来获取我插入了多少列:

p cas_client.count_columns(TestColumnFamily,TestRow)

此脚本再次崩溃，同样的错误信息。并且 cassandra 进程保持 100% 的 cpu 使用率。

AWS m1.xlarge type instance (15GB mem,800GB harddisk, 4cores cpu)
cassandra-1.1.2
ruby-1.9.3-p194
jdk-7u6-linux-x64
ruby-gems:
    cassandra (0.15.0)
    thrift (0.8.0)
    thrift_client (0.8.1)

问题是什么？

Answer 1

10,000 列，每列 1 MB 是 10 GB 的数据。

Cassandra rpc 使用 thrift，这要求 rpc 调用的整个返回值必须适合内存，因此尝试读取所有列将需要您将 10 gig thrift 对象加载到内存中，这是不切实际的，尤其是在 ruby​​ 中.