How To Solve Issues Related to Log – Version; pid; build/

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Updated: Feb-20

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Troubleshooting background

To troubleshoot Elasticsearch log “Version; pid; build/” it’s important to understand common problems related to Elasticsearch concepts: node. See detailed explanations below complete with common problems, examples and useful tips.

Nodes in Elasticsearch

What it is

Simply explained a node is a single server that is part of a cluster. Each node is assigned with one or more roles, which describes the node responsibility and operations – Data nodes stores the data, and participates in the cluster’s indexing and search capabilities, while master nodes are responsible for managing the cluster activities and storing the cluster state, including the metadata.

While it’s possible to run several Node instances of Elasticsearch on the same hardware, it’s considered a best practice to limit a server to a single running instance of Elasticsearch.

Nodes connect to each other and form a cluster by using a discovery method. 

Roles
Master node

Master nodes are in charge of cluster-wide settings and changes  – deleting or creating indices and fields, adding or removing nodes and allocating shards to nodes. Each cluster has a single master node that is elected from the master eligible nodes using a distributed consensus algorithm and is reelected if the current master node fails.

Coordinator Node (aka client node)

Coordinator Node – is a node that does not hold any configured role. It doesn’t hold data, not part of the master eligible group nor execute ingest pipelines. Coordinator node serves incoming search requests and is acting as the query coordinator – running the query and fetch phases, sending requests to every node which holds a shard being queried. The client node also distributes bulk indexing operations and route queries to shards copies based on the nodes responsiveness.

Version in Elasticsearch


A version corresponds to the Elasticsearch built-in tracking system that tracks the changes in each document’s update. When a document is indexed for the first time, it is assigned a version 1 using _version key. When the same document gets a subsequent update, the _version is incremented by 1 with every index, update or delete API call.

What it is used for

A version is used to handle the concurrency issues in Elasticsearch which come into play during simultaneous accessing of an index by multiple users. Elasticsearch handles this issue with an optimistic locking concept using the _version parameter to avoid letting multiple users edit the same document at the same time and protects users from generating incorrect data.

Notes

You cannot see the history of the document using _version. That means Elasticsearch does not use _version to keep a track of original changes that had been performed on the document. For example, if a document has been updated 10 times, it’s _version would be marked by Elasticsearch as 11, but you cannot go back and see what version 5 of the document looked like. This has to be implemented independently.

Common Problems

If optimistic locking is not implemented while making updates to a document, Elasticsearch may return a conflict error with the 409 status code, which means that multiple users are trying to update the same version of the document at the same time.

POST /ratings/123?version=50
{
    "name": "Joker",
    "rating": 50
}

To help troubleshoot related issues we have gathered selected Q&A from the community and issues from Github , please review the following for further information :

1 Github Issue Number 26080  

2Elasticsearch 7 0 Recent Installed  


Log Context

Log ”version[{}]; pid[{}]; build[{}/{}]” classname is Node.java
We have extracted the following from Elasticsearch source code to get an in-depth context :

         Settings tmpSettings = settingsBuilder().put(tmpEnv.settings())
                .put(Client.CLIENT_TYPE_SETTING; CLIENT_TYPE).build();
        tmpSettings = TribeService.processSettings(tmpSettings);

        ESLogger logger = Loggers.getLogger(Node.class; tmpSettings.get("name"));
        logger.info("version[{}]; pid[{}]; build[{}/{}]"; version; JvmInfo.jvmInfo().pid(); Build.CURRENT.hashShort(); Build.CURRENT.timestamp());

        logger.info("initializing ...");

        if (logger.isDebugEnabled()) {
            logger.debug("using config [{}]; data [{}]; logs [{}]; plugins [{}]";






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