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From "Junping Du (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (YARN-4576) Pluggable blacklist/whitelist policies in launching AM to protect AM failed multiple times on problematic nodes
Date Wed, 13 Jan 2016 17:02:39 GMT

     [ https://issues.apache.org/jira/browse/YARN-4576?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Junping Du updated YARN-4576:
-----------------------------
    Description: 
Before YARN-2005, YARN blacklist mechanism is to track the bad nodes by AM:  If AM tried to
launch containers on a specific node get failed for several times, AM will blacklist this
node in future resource asking. This mechanism works fine for normal containers. However,
from our observation on behaviors of several clusters: if this problematic node launch AM
failed, then RM could pickup this problematic node to launch next AM attempts again and again
that cause application failure in case other functional nodes are busy. In normal case, the
customized healthy checker script cannot be so sensitive to mark node as unhealthy when one
or two containers get launched failed. 

After YARN-2005, we can have a BlacklistManager in each RMapp, so those nodes who launching
AM attempts failed for specific application before will get blacklisted. To get rid of potential
risks that all nodes being blacklisted by BlacklistManager, a disable-failure-threshold is
involved to stop adding more nodes into blacklist if hit certain ratio already. 

There are already some enhancements for this AM blacklist mechanism: YARN-4284 is to address
the more wider case for AM container get launched failure and YARN-4389 tries to make configuration
settings available for change by App to meet app specific requirement. However, there are
still several gaps to address more scenarios:
1. We may need a global blacklist instead of each app maintain a separated one. The reason
is: AM could get more chance to fail if other AM get failed before. A quick example is: in
a busy cluster, all nodes are busy except two problematic nodes: node a and node b, app1 already
submit and get failed in two AM attempts on a and b. app2 and other apps should wait for other
busy nodes rather than waste attempts on these two problematic nodes.
2. If AM container failure is recognized as global event instead app own issue, we should
consider the blacklist is not a permanent thing but with a specific time window. 
3. We could have user defined black list polices to address more possible cases and scenarios,
so it reasonable to make blacklist policy pluggable.
4. For some test scenario, we could have whitelist mechanism for AM launching.
5. Some minor issues: it sounds like NM reconnect won't refresh blacklist so far.
Will try to address all issues here.

  was:Current YARN blacklist mechanism is to track the bad nodes by AM: If AM tried to launch
containers on a specific node get failed for several times, AM will blacklist this node in
future resource asking. This mechanism works fine for normal containers. However, from our
observation on behaviors of several clusters: if this problematic node launch AM failed, then
RM could pickup this problematic node to launch next AM attempts again and again that cause
application failure in case other functional nodes are busy. In normal case, the customized
healthy checker script cannot be so sensitive to mark node as unhealthy when one or two containers
get launched failed. However, in RM side, we can blacklist these nodes for launching AM for
a certain time if launching AMs get failed before.


> Pluggable blacklist/whitelist policies in launching AM to protect AM failed multiple
times on problematic nodes
> ---------------------------------------------------------------------------------------------------------------
>
>                 Key: YARN-4576
>                 URL: https://issues.apache.org/jira/browse/YARN-4576
>             Project: Hadoop YARN
>          Issue Type: Improvement
>          Components: resourcemanager
>            Reporter: Junping Du
>            Assignee: Junping Du
>            Priority: Critical
>
> Before YARN-2005, YARN blacklist mechanism is to track the bad nodes by AM:  If AM tried
to launch containers on a specific node get failed for several times, AM will blacklist this
node in future resource asking. This mechanism works fine for normal containers. However,
from our observation on behaviors of several clusters: if this problematic node launch AM
failed, then RM could pickup this problematic node to launch next AM attempts again and again
that cause application failure in case other functional nodes are busy. In normal case, the
customized healthy checker script cannot be so sensitive to mark node as unhealthy when one
or two containers get launched failed. 
> After YARN-2005, we can have a BlacklistManager in each RMapp, so those nodes who launching
AM attempts failed for specific application before will get blacklisted. To get rid of potential
risks that all nodes being blacklisted by BlacklistManager, a disable-failure-threshold is
involved to stop adding more nodes into blacklist if hit certain ratio already. 
> There are already some enhancements for this AM blacklist mechanism: YARN-4284 is to
address the more wider case for AM container get launched failure and YARN-4389 tries to make
configuration settings available for change by App to meet app specific requirement. However,
there are still several gaps to address more scenarios:
> 1. We may need a global blacklist instead of each app maintain a separated one. The reason
is: AM could get more chance to fail if other AM get failed before. A quick example is: in
a busy cluster, all nodes are busy except two problematic nodes: node a and node b, app1 already
submit and get failed in two AM attempts on a and b. app2 and other apps should wait for other
busy nodes rather than waste attempts on these two problematic nodes.
> 2. If AM container failure is recognized as global event instead app own issue, we should
consider the blacklist is not a permanent thing but with a specific time window. 
> 3. We could have user defined black list polices to address more possible cases and scenarios,
so it reasonable to make blacklist policy pluggable.
> 4. For some test scenario, we could have whitelist mechanism for AM launching.
> 5. Some minor issues: it sounds like NM reconnect won't refresh blacklist so far.
> Will try to address all issues here.



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