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https://issues.apache.org/jira/browse/HBASE-12943?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15246374#comment-15246374
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Gary Helmling commented on HBASE-12943:
---------------------------------------
Recent versions of JDK 7 and 8 that I've seen only set this to "forever" when a
SecurityManager is in use. Otherwise the default seems to be 30 seconds:
{quote}
#
# The Java-level namelookup cache policy for successful lookups:
#
# any negative value: caching forever
# any positive value: the number of seconds to cache an address for
# zero: do not cache
#
# default value is forever (FOREVER). For security reasons, this
# caching is made forever when a security manager is set. When a security
# manager is not set, the default behavior in this implementation
# is to cache for 30 seconds.
#
# NOTE: setting this to anything other than the default value can have
# serious security implications. Do not set it unless
# you are sure you are not exposed to DNS spoofing attack.
#
#networkaddress.cache.ttl=-1
{quote}
Given this, the overhead in added lookups from HBASE-13067 can be pretty
severe. Should we set {{networkadress.cache.ttl}} to a longer value in HBase,
or maybe consider changing the default setting for
{{hbase.resolve.hostnames.on.failure}}? As far as I can see, HBASE-13067 is
otherwise triggering a hostname lookup on every call, not just on failure.
> Set sun.net.inetaddr.ttl in HBase
> ---------------------------------
>
> Key: HBASE-12943
> URL: https://issues.apache.org/jira/browse/HBASE-12943
> Project: HBase
> Issue Type: Bug
> Reporter: Liu Shaohui
> Assignee: Liu Shaohui
> Fix For: 2.0.0, 1.3.0, 1.2.2
>
> Attachments: 12943-1-master.txt
>
>
> The default value of config: sun.net.inetaddr.ttl is -1 and the java
> processes will cache the mapping of hostname to ip address forever, See:
> http://docs.oracle.com/javase/7/docs/technotes/guides/net/properties.html
> But things go wrong when a regionserver with same hostname and different ip
> address rejoins the hbase cluster. The HMaster will get wrong ip address of
> the regionserver from this cache and every region assignment to this
> regionserver will be blocked for a time because the HMaster can't communicate
> with the regionserver.
> A tradeoff is to set the sun.net.inetaddr.ttl to 10m or 1h and make the wrong
> cache expired.
> Suggestions are welcomed. Thanks~
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