hadoop-yarn-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Chris Trezzo (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (YARN-5767) Fix the order that resources are cleaned up from the local Public/Private caches
Date Fri, 28 Oct 2016 17:17:59 GMT

    [ https://issues.apache.org/jira/browse/YARN-5767?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15615991#comment-15615991
] 

Chris Trezzo commented on YARN-5767:
------------------------------------

I have filed a followup jira for the metrics: YARN-5797

> Fix the order that resources are cleaned up from the local Public/Private caches
> --------------------------------------------------------------------------------
>
>                 Key: YARN-5767
>                 URL: https://issues.apache.org/jira/browse/YARN-5767
>             Project: Hadoop YARN
>          Issue Type: Bug
>    Affects Versions: 2.6.0, 2.7.0, 3.0.0-alpha1
>            Reporter: Chris Trezzo
>            Assignee: Chris Trezzo
>              Labels: oct16-easy
>             Fix For: 2.8.0, 3.0.0-alpha2
>
>         Attachments: YARN-5767-trunk-v1.patch, YARN-5767-trunk-v2.patch, YARN-5767-trunk-v3.patch,
YARN-5767-trunk-v4.patch
>
>
> If you look at {{ResourceLocalizationService#handleCacheCleanup}}, you can see that public
resources are added to the {{ResourceRetentionSet}} first followed by private resources:
> {code:java}
> private void handleCacheCleanup(LocalizationEvent event) {
>   ResourceRetentionSet retain =
>     new ResourceRetentionSet(delService, cacheTargetSize);
>   retain.addResources(publicRsrc);
>   if (LOG.isDebugEnabled()) {
>     LOG.debug("Resource cleanup (public) " + retain);
>   }
>   for (LocalResourcesTracker t : privateRsrc.values()) {
>     retain.addResources(t);
>     if (LOG.isDebugEnabled()) {
>       LOG.debug("Resource cleanup " + t.getUser() + ":" + retain);
>     }
>   }
>   //TODO Check if appRsrcs should also be added to the retention set.
> }
> {code}
> Unfortunately, if we look at {{ResourceRetentionSet#addResources}} we see that this means
public resources are deleted first until the target cache size is met:
> {code:java}
> public void addResources(LocalResourcesTracker newTracker) {
>   for (LocalizedResource resource : newTracker) {
>     currentSize += resource.getSize();
>     if (resource.getRefCount() > 0) {
>       // always retain resources in use
>       continue;
>     }
>     retain.put(resource, newTracker);
>   }
>   for (Iterator<Map.Entry<LocalizedResource,LocalResourcesTracker>> i =
>          retain.entrySet().iterator();
>        currentSize - delSize > targetSize && i.hasNext();) {
>     Map.Entry<LocalizedResource,LocalResourcesTracker> rsrc = i.next();
>     LocalizedResource resource = rsrc.getKey();
>     LocalResourcesTracker tracker = rsrc.getValue();
>     if (tracker.remove(resource, delService)) {
>       delSize += resource.getSize();
>       i.remove();
>     }
>   }
> }
> {code}
> The result of this is that resources in the private cache are only deleted in the cases
where:
> # The cache size is larger than the target cache size and the public cache is empty.
> # The cache size is larger than the target cache size and everything in the public cache
is being used by a running container.
> For clusters that primarily use the public cache (i.e. make use of the shared cache),
this means that the most commonly used resources can be deleted before old resources in the
private cache. Furthermore, the private cache can continue to grow over time causing more
and more churn in the public cache.
> Additionally, the same problem exists within the private cache. Since resources are added
to the retention set on a user by user basis, resources will get cleaned up one user at a
time in the order that privateRsrc.values() returns the LocalResourcesTracker. So if user1
has 10MB in their cache and user2 has 100MB in their cache and the target size of the cache
is 50MB, user1 could potentially have their entire cache removed before anything is deleted
from the user2 cache.



--
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


Mime
View raw message