cassandra datastax驱动程序抛出写入超时

Question

在进行批量加载数据时,根据日志数据递增计数器,我遇到了超时异常.我使用Datastax 2.0-rc2 java驱动程序.

这是服务器无法跟上的问题(即服务器端配置问题),还是客户端厌倦等待服务器响应的问题？无论哪种方式,是否有一个简单的配置更改我可以做到这将解决这个问题？

Exception in thread "main" com.datastax.driver.core.exceptions.WriteTimeoutException: Cassandra timeout during write query at consistency ONE (1 replica were required but only 0 acknowledged the write)
    at com.datastax.driver.core.exceptions.WriteTimeoutException.copy(WriteTimeoutException.java:54)
    at com.datastax.driver.core.ResultSetFuture.extractCauseFromExecutionException(ResultSetFuture.java:271)
    at com.datastax.driver.core.ResultSetFuture.getUninterruptibly(ResultSetFuture.java:187)
    at com.datastax.driver.core.Session.execute(Session.java:126)
    at jason.Stats.analyseLogMessages(Stats.java:91)
    at jason.Stats.main(Stats.java:48)
Caused by: com.datastax.driver.core.exceptions.WriteTimeoutException: Cassandra timeout during write query at consistency ONE (1 replica were required but only 0 acknowledged the write)
    at com.datastax.driver.core.exceptions.WriteTimeoutException.copy(WriteTimeoutException.java:54)
    at com.datastax.driver.core.Responses$Error.asException(Responses.java:92)
    at com.datastax.driver.core.ResultSetFuture$ResponseCallback.onSet(ResultSetFuture.java:122)
    at com.datastax.driver.core.RequestHandler.setFinalResult(RequestHandler.java:224)
    at com.datastax.driver.core.RequestHandler.onSet(RequestHandler.java:373)
    at com.datastax.driver.core.Connection$Dispatcher.messageReceived(Connection.java:510)
    at org.jboss.netty.channel.SimpleChannelUpstreamHandler.handleUpstream(SimpleChannelUpstreamHandler.java:70)
    at org.jboss.netty.channel.DefaultChannelPipeline.sendUpstream(DefaultChannelPipeline.java:564)
    at org.jboss.netty.channel.DefaultChannelPipeline$DefaultChannelHandlerContext.sendUpstream(DefaultChannelPipeline.java:791)
    at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:296)
    at org.jboss.netty.handler.codec.oneone.OneToOneDecoder.handleUpstream(OneToOneDecoder.java:70)
    at org.jboss.netty.channel.DefaultChannelPipeline.sendUpstream(DefaultChannelPipeline.java:564)
    at org.jboss.netty.channel.DefaultChannelPipeline$DefaultChannelHandlerContext.sendUpstream(DefaultChannelPipeline.java:791)
    at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:296)
    at org.jboss.netty.handler.codec.frame.FrameDecoder.unfoldAndFireMessageReceived(FrameDecoder.java:462)
    at org.jboss.netty.handler.codec.frame.FrameDecoder.callDecode(FrameDecoder.java:443)
    at org.jboss.netty.handler.codec.frame.FrameDecoder.messageReceived(FrameDecoder.java:303)
    at org.jboss.netty.channel.SimpleChannelUpstreamHandler.handleUpstream(SimpleChannelUpstreamHandler.java:70)
    at org.jboss.netty.channel.DefaultChannelPipeline.sendUpstream(DefaultChannelPipeline.java:564)
    at org.jboss.netty.channel.DefaultChannelPipeline.sendUpstream(DefaultChannelPipeline.java:559)
    at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:268)
    at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:255)
    at org.jboss.netty.channel.socket.nio.NioWorker.read(NioWorker.java:88)
    at org.jboss.netty.channel.socket.nio.AbstractNioWorker.process(AbstractNioWorker.java:109)
    at org.jboss.netty.channel.socket.nio.AbstractNioSelector.run(AbstractNioSelector.java:312)
    at org.jboss.netty.channel.socket.nio.AbstractNioWorker.run(AbstractNioWorker.java:90)
    at org.jboss.netty.channel.socket.nio.NioWorker.run(NioWorker.java:178)
    at org.jboss.netty.util.ThreadRenamingRunnable.run(ThreadRenamingRunnable.java:108)
    at org.jboss.netty.util.internal.DeadLockProofWorker$1.run(DeadLockProofWorker.java:42)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:744)
Caused by: com.datastax.driver.core.exceptions.WriteTimeoutException: Cassandra timeout during write query at consistency ONE (1 replica were required but only 0 acknowledged the write)
    at com.datastax.driver.core.Responses$Error$1.decode(Responses.java:53)
    at com.datastax.driver.core.Responses$Error$1.decode(Responses.java:33)
    at com.datastax.driver.core.Message$ProtocolDecoder.decode(Message.java:165)
    at org.jboss.netty.handler.codec.oneone.OneToOneDecoder.handleUpstream(OneToOneDecoder.java:66)
    ... 21 more

其中一个节点大致在发生时报告:

ERROR [Native-Transport-Requests:12539] 2014-02-16 23:37:22,191 ErrorMessage.java (line 222) Unexpected exception during request
java.io.IOException: Connection reset by peer
    at sun.nio.ch.FileDispatcherImpl.read0(Native Method)
    at sun.nio.ch.SocketDispatcher.read(Unknown Source)
    at sun.nio.ch.IOUtil.readIntoNativeBuffer(Unknown Source)
    at sun.nio.ch.IOUtil.read(Unknown Source)
    at sun.nio.ch.SocketChannelImpl.read(Unknown Source)
    at org.jboss.netty.channel.socket.nio.NioWorker.read(NioWorker.java:64)
    at org.jboss.netty.channel.socket.nio.AbstractNioWorker.process(AbstractNioWorker.java:109)
    at org.jboss.netty.channel.socket.nio.AbstractNioSelector.run(AbstractNioSelector.java:312)
    at org.jboss.netty.channel.socket.nio.AbstractNioWorker.run(AbstractNioWorker.java:90)
    at org.jboss.netty.channel.socket.nio.NioWorker.run(NioWorker.java:178)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)

Answer 1

虽然我不明白这个问题的根本原因,但我能够通过增加conf/cassandra.yaml文件中的超时值来解决问题.

write_request_timeout_in_ms: 20000

Answer 2

我们在连接了SAN存储的ESX群集中的单个节点上遇到类似问题(数据存档不推荐这种情况,但此时我们没有其他选项).

注意: 下面的设置可能对Cassandra可以实现的最大性能有很大影响,但我们选择了稳定的系统而不是高性能.

在运行时,iostat -xmt 1我们发现WriteTimeoutExceptions同时出现了高w_await时间.事实证明,memtable无法在默认write_request_timeout_in_ms: 2000设置下写入磁盘.

我们将memtable大小从512Mb(默认为堆空间的25%,在我们的情况下为2Gb)显着减少到32Mb:

# Total permitted memory to use for memtables. Cassandra will stop
# accepting writes when the limit is exceeded until a flush completes,
# and will trigger a flush based on memtable_cleanup_threshold
# If omitted, Cassandra will set both to 1/4 the size of the heap.
# memtable_heap_space_in_mb: 2048
memtable_offheap_space_in_mb: 32

我们还将写入超时略微增加到3秒:

write_request_timeout_in_ms: 3000

如果IO等待时间过长,还要确保定期写入磁盘:

#commitlog_sync: batch
#commitlog_sync_batch_window_in_ms: 2
#
# the other option is "periodic" where writes may be acked immediately
# and the CommitLog is simply synced every commitlog_sync_period_in_ms
# milliseconds.
commitlog_sync: periodic
commitlog_sync_period_in_ms: 10000

这些设置允许记忆保持较小并经常书写.异常得以解决,我们在系统上运行的压力测试中幸存下来.