ElasticSearch gives error about queue size

Question

RemoteTransportException[[Death][inet[/172.18.0.9:9300]][bulk/shard]]; nested: EsRejectedExecutionException[rejected execution (queue capacity 50) on org.elasticsearch.action.support.replication.TransportShardReplicationOperationAction$AsyncShardOperationAction$1@12ae9af];

Does this mean I'm doing too many operations in one bulk at one time, or too many bulks in a row, or what? Is there a setting I should be increasing or something I should be doing differently?

One thread suggests "I think you need to increase your 'threadpool.bulk.queue_size' (and possibly 'threadpool.index.queue_size') setting due to recent defaults." However, I don't want to arbitrarily increase a setting without understanding the fault.

Answer 1

I lack the reputation to reply to the comment as a comment.

It's not exactly the number of bulk requests made, it is actually the total number of shards that will be updated on a given node by the bulk calls. This means the contents of the actual bulk operations inside the bulk request actually matter. For instance, if you have a single node, with a single index, running on an 8 core box, with 60 shards and you issue a bulk request that has indexing operations that affects all 60 shards, you will get this error message with a single bulk request.

If anyone wants to change this, you can see the splitting happening inside of org.elasticsearch.action.bulk.TransportBulkAction.executeBulk() near the comment "go over all the request and create a ShardId". The individual requests happen a few lines down around line 293 on version 1.2.1.

Answer 2

You want to up the number of bulk threads available in the thread pool. ES sets aside threads in several named pools for use on various tasks. These pools have a few settings; type, size, and queue size.

from the docs:

The queue_size allows to control the size of the queue of pending requests that have no threads to execute them. By default, it is set to -1 which means its unbounded. When a request comes in and the queue is full, it will abort the request.

To me that means you have more bulk requests queued up waiting for a thread from the pool to execute one of them than your current queue size. The documentation seems to indicate the queue size is defaulted to both -1 (the text above says that) and 50 (the call out for bulk in the doc says that). You could take a look at the source to be sure for your version of es OR set the higher number and see if your bulk issues simply go away.

ES thread pool settings doco