[jira] [Comment Edited] (YARN-4757) [Umbrella] Simplified discovery of services via DNS mechanisms

["Jian He (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/YARN-4757?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15315054#comment-15315054 ] 

Jian He edited comment on YARN-4757 at 6/3/16 10:59 PM:
--------------------------------------------------------

Hi [~jmaron],  thanks for working on this.  I went through the patch and have a few questions:

- Here, it’s using the ‘description’ filed for constructing the DNS name. is this expected ? seems not mentioned in the doc
{code}
protected Name getContainerName()
    throws PathNotFoundException, TextParseException {
  String service = RegistryPathUtils.lastPathEntry(
      RegistryPathUtils.parentOf(RegistryPathUtils.parentOf(getPath())));
  String description = getRecord().description.toLowerCase();
  String user = getUsername(getPath());
  return Name.fromString(MessageFormat.format("{0}.{1}.{2}.{3}",
      description,
      service,
      user,
      domain));
{code}
- we can close the CuratorService#treeCache when stop the service?
- only readLock is being used. wondering whether these locks are needed.
{code}
private ReentrantReadWriteLock zoneLock = new ReentrantReadWriteLock();
private CloseableLock readLock = new CloseableLock(zoneLock.readLock());
private CloseableLock writeLock = new CloseableLock(zoneLock.writeLock());
{code}
- question about the dnsEnabled config, if the dnsEnabled is false, what else does the RegistryDNSServer do ? Asking this because I'm wondering whether this config is actually needed. 
- RecordCreatorFactory: The RecordCreatroFactory#getRecordCreator is instantiating the creator instance every time this method gets called. May be singleton pattern could be useful to avoid creating a new instance every time.   
- DNSManagementOperations class is not used anywhere , can be removed?
- a few unused methods in RegistryDNS, e.g. addDSRecord, signZones. is this intended ?
- what does the RegistryDNS#primaryDNS do ? 


was (Author: jianhe):
Hi [~jmaron],  thanks for working on this.  I went through the patch and have a few questions:

- Here, it’s using the ‘description’ filed for constructing the DNS name. is this expected ? seems not mentioned in the doc
{code}
protected Name getContainerName()
    throws PathNotFoundException, TextParseException {
  String service = RegistryPathUtils.lastPathEntry(
      RegistryPathUtils.parentOf(RegistryPathUtils.parentOf(getPath())));
  String description = getRecord().description.toLowerCase();
  String user = getUsername(getPath());
  return Name.fromString(MessageFormat.format("{0}.{1}.{2}.{3}",
      description,
      service,
      user,
      domain));
{code}
- we can close the CuratorService#treeCache when stop the service?
- only readLock is being used. wondering whether these locks are needed.
{code}
private ReentrantReadWriteLock zoneLock = new ReentrantReadWriteLock();
private CloseableLock readLock = new CloseableLock(zoneLock.readLock());
private CloseableLock writeLock = new CloseableLock(zoneLock.writeLock());
{code}
- question about the dnsEnabled config, if the dnsEnabled is false, what else does the RegistryDNSServer do ?
- RecordCreatorFactory: The RecordCreatroFactory#getRecordCreator is instantiating the creator instance every time this method gets called. May be singleton pattern could be useful to avoid creating a new instance every time.   
- DNSManagementOperations class is not used anywhere , can be removed?
- a few unused methods in RegistryDNS, e.g. addDSRecord, signZones. is this intended ?
- what does the RegistryDNS#primaryDNS do ? 

> [Umbrella] Simplified discovery of services via DNS mechanisms
> --------------------------------------------------------------
>
>                 Key: YARN-4757
>                 URL: https://issues.apache.org/jira/browse/YARN-4757
>             Project: Hadoop YARN
>          Issue Type: New Feature
>            Reporter: Vinod Kumar Vavilapalli
>            Assignee: Jonathan Maron
>         Attachments: 0001-YARN-4757-Initial-code-submission-for-DNS-Service.patch, YARN-4757- Simplified discovery of services via DNS mechanisms.pdf, YARN-4757-YARN-4757.001.patch, YARN-4757-YARN-4757.002.patch, YARN-4757-YARN-4757.003.patch
>
>
> [See overview doc at YARN-4692, copying the sub-section (3.2.10.2) to track all related efforts.]
> In addition to completing the present story of service­-registry (YARN-913), we also need to simplify the access to the registry entries. The existing read mechanisms of the YARN Service Registry are currently limited to a registry specific (java) API and a REST interface. In practice, this makes it very difficult for wiring up existing clients and services. For e.g, dynamic configuration of dependent end­points of a service is not easy to implement using the present registry­-read mechanisms, *without* code-changes to existing services.
> A good solution to this is to expose the registry information through a more generic and widely used discovery mechanism: DNS. Service Discovery via DNS uses the well-­known DNS interfaces to browse the network for services. YARN-913 in fact talked about such a DNS based mechanism but left it as a future task. (Task) Having the registry information exposed via DNS simplifies the life of services.



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

---------------------------------------------------------------------
To unsubscribe, e-mail: yarn-issues-unsubscribe@hadoop.apache.org
For additional commands, e-mail: yarn-issues-help@hadoop.apache.org