用于并行搜索的Elasticsearch中的EsRejectedExecutionException

Question

我正在使用我的应用程序中的单个传输客户端实例在Elasticsearch中查询多个并行请求。

对于并行执行，我得到了以下异常。如何克服这个问题。

org.elasticsearch.common.util.concurrent.EsRejectedExecutionException: rejected execution (queue capacity 1000) on org.elasticsearch.search.action.SearchServiceTransportAction$23@5f804c60
    at org.elasticsearch.common.util.concurrent.EsAbortPolicy.rejectedExecution(EsAbortPolicy.java:62)
    at java.util.concurrent.ThreadPoolExecutor.reject(ThreadPoolExecutor.java:821)
    at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1372)
    at org.elasticsearch.search.action.SearchServiceTransportAction.execute(SearchServiceTransportAction.java:509)
    at org.elasticsearch.search.action.SearchServiceTransportAction.sendExecuteScan(SearchServiceTransportAction.java:441)
    at org.elasticsearch.action.search.type.TransportSearchScanAction$AsyncAction.sendExecuteFirstPhase(TransportSearchScanAction.java:68)
    at org.elasticsearch.action.search.type.TransportSearchTypeAction$BaseAsyncAction.performFirstPhase(TransportSearchTypeAction.java:171)
    at org.elasticsearch.action.search.type.TransportSearchTypeAction$BaseAsyncAction.start(TransportSearchTypeAction.java:153)
    at org.elasticsearch.action.search.type.TransportSearchScanAction.doExecute(TransportSearchScanAction.java:52)
    at org.elasticsearch.action.search.type.TransportSearchScanAction.doExecute(TransportSearchScanAction.java:42)
    at org.elasticsearch.action.support.TransportAction.execute(TransportAction.java:63)
    at org.elasticsearch.action.search.TransportSearchAction.doExecute(TransportSearchAction.java:107)
    at org.elasticsearch.action.search.TransportSearchAction.doExecute(TransportSearchAction.java:43)
    at org.elasticsearch.action.support.TransportAction.execute(TransportAction.java:63)
    at org.elasticsearch.action.search.TransportSearchAction$TransportHandler.messageReceived(TransportSearchAction.java:124)
    at org.elasticsearch.action.search.TransportSearchAction$TransportHandler.messageReceived(TransportSearchAction.java:113)
    at org.elasticsearch.transport.netty.MessageChannelHandler.handleRequest(MessageChannelHandler.java:212)
    at org.elasticsearch.transport.netty.MessageChannelHandler.messageReceived(MessageChannelHandler.java:109)
    at org.elasticsearch.common.netty.channel.SimpleChannelUpstreamHandler.handleUpstream(SimpleChannelUpstreamHandler.java:70)
    at org.elasticsearch.common.netty.channel.DefaultChannelPipeline.sendUpstream(DefaultChannelPipeline.java:564)
    at org.elasticsearch.common.netty.channel.DefaultChannelPipeline$DefaultChannelHandlerContext.sendUpstream(DefaultChannelPipeline.java:791)
    at org.elasticsearch.common.netty.channel.Channels.fireMessageReceived(Channels.java:296)
    at org.elasticsearch.common.netty.handler.codec.frame.FrameDecoder.unfoldAndFireMessageReceived(FrameDecoder.java:462)
    at org.elasticsearch.common.netty.handler.codec.frame.FrameDecoder.callDecode(FrameDecoder.java:443)
    at org.elasticsearch.common.netty.handler.codec.frame.FrameDecoder.messageReceived(FrameDecoder.java:303)
    at org.elasticsearch.common.netty.channel.SimpleChannelUpstreamHandler.handleUpstream(SimpleChannelUpstreamHandler.java:70)
    at org.elasticsearch.common.netty.channel.DefaultChannelPipeline.sendUpstream(DefaultChannelPipeline.java:564)
    at org.elasticsearch.common.netty.channel.DefaultChannelPipeline$DefaultChannelHandlerContext.sendUpstream(DefaultChannelPipeline.java:791)
    at org.elasticsearch.common.netty.OpenChannelsHandler.handleUpstream(OpenChannelsHandler.java:74)
    at org.elasticsearch.common.netty.channel.DefaultChannelPipeline.sendUpstream(DefaultChannelPipeline.java:564)
    at org.elasticsearch.common.netty.channel.DefaultChannelPipeline.sendUpstream(DefaultChannelPipeline.java:559)
    at org.elasticsearch.common.netty.channel.Channels.fireMessageReceived(Channels.java:268)
    at org.elasticsearch.common.netty.channel.Channels.fireMessageReceived(Channels.java:255)
    at org.elasticsearch.common.netty.channel.socket.nio.NioWorker.read(NioWorker.java:88)
    at org.elasticsearch.common.netty.channel.socket.nio.AbstractNioWorker.process(AbstractNioWorker.java:108)
    at org.elasticsearch.common.netty.channel.socket.nio.AbstractNioSelector.run(AbstractNioSelector.java:318)
    at org.elasticsearch.common.netty.channel.socket.nio.AbstractNioWorker.run(AbstractNioWorker.java:89)
    at org.elasticsearch.common.netty.channel.socket.nio.NioWorker.run(NioWorker.java:178)
    at org.elasticsearch.common.netty.util.ThreadRenamingRunnable.run(ThreadRenamingRunnable.java:108)
    at org.elasticsearch.common.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:745)

Answer 1

Elasticsearch有一个线程池和一个用于每个节点搜索的队列。线程池将具有N个准备就绪的工作者来处理请求。当请求到来且工作人员空闲时，由工作人员处理。现在默认情况下，工作程序数量等于该CPU上的内核数量。当工作人员忙碌并且有更多搜索请求时，该请求将进入队列。队列的大小也受到限制。如果默认大小为100，并且如果发生的并行请求多于此，那么这些请求将被拒绝，正如您在错误日志中看到的那样。

解决方案：

1. 对此的直接解决方案是增加搜索队列的大小。我们还可以增加线程池的大小，但这可能会严重影响单个查询的性能。因此，增加队列可能是一个好主意。但是请记住，此队列位于内存中，过多增加队列大小可能会导致内存不足问题。（更多信息）

2. 增加节点和副本的数量-请记住，每个节点都有自己的搜索线程池/队列。此外，搜索可以在主分片或副本上进行。