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https://issues.apache.org/jira/browse/HDFS-4417?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13559116#comment-13559116
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Todd Lipcon commented on HDFS-4417:
-----------------------------------
{code}
- private Peer newPeer(InetSocketAddress addr) throws IOException {
+ private Peer newRemotePeer(InetSocketAddress addr) throws IOException {
{code}
How about {{newTcpPeer}}? Remote is kind of vague.
----
{code}
+ public static DomainSocket getClosedSocket() {
+ return new DomainSocket("", -1);
+ }
{code}
This doesn't seem like a reasonable thing to expose. Instead, since it's just
used from tests, could you just create a mock DomainSocket object which throws
ClosedChannelException on write?
----
I think the changes to PeerCache are a little over-complicated... why not just
have two separate PeerCaches, one for each type of peer?
> HDFS-347: fix case where local reads get disabled incorrectly
> -------------------------------------------------------------
>
> Key: HDFS-4417
> URL: https://issues.apache.org/jira/browse/HDFS-4417
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: datanode, hdfs-client, performance
> Reporter: Todd Lipcon
> Assignee: Colin Patrick McCabe
> Attachments: HDFS-4417.002.patch, hdfs-4417.txt
>
>
> In testing HDFS-347 against HBase (thanks [~jdcryans]) we ran into the
> following case:
> - a workload is running which puts a bunch of local sockets in the PeerCache
> - the workload abates for a while, causing the sockets to go "stale" (ie the
> DN side disconnects after the keepalive timeout)
> - the workload starts again
> In this case, the local socket retrieved from the cache failed the
> newBlockReader call, and it incorrectly disabled local sockets on that host.
> This is similar to an earlier bug HDFS-3376, but not quite the same.
> The next issue we ran into is that, once this happened, it never tried local
> sockets again, because the cache held lots of TCP sockets. Since we always
> managed to get a cached socket to the local node, it didn't bother trying
> local read again.
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