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https://issues.apache.org/jira/browse/HDFS-17030?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17728169#comment-17728169
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ASF GitHub Bot commented on HDFS-17030:
---------------------------------------
xinglin commented on code in PR #5700:
URL: https://github.com/apache/hadoop/pull/5700#discussion_r1212423619
##########
hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/server/namenode/ha/ObserverReadProxyProvider.java:
##########
@@ -213,6 +241,13 @@ public ObserverReadProxyProvider(
observerProbeRetryPeriodMs = conf.getTimeDuration(
OBSERVER_PROBE_RETRY_PERIOD_KEY,
OBSERVER_PROBE_RETRY_PERIOD_DEFAULT, TimeUnit.MILLISECONDS);
+ namenodeHAStateProbeTimeoutSec = conf.getTimeDuration(
+ NAMENODE_HA_STATE_PROBE_TIMEOUT,
+ NAMENODE_HA_STATE_PROBE_TIMEOUT_DEFAULT, TimeUnit.SECONDS);
+ // Disallow negative values for namenodeHAStateProbeTimeoutSec
+ if (namenodeHAStateProbeTimeoutSec < 0) {
+ namenodeHAStateProbeTimeoutSec = NAMENODE_HA_STATE_PROBE_TIMEOUT_DEFAULT;
+ }
Review Comment:
It is unfortunate that Future in Java uses two separate APIs when waiting to
get the result: get(timeout) and get(), which waits without a timeout.
Changed the code with an if case, to support the case where
namenodeHAStateProbeTimeoutSec is less or equal to 0 (no timeout).
> Limit wait time for getHAServiceState in ObserverReaderProxy
> ------------------------------------------------------------
>
> Key: HDFS-17030
> URL: https://issues.apache.org/jira/browse/HDFS-17030
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: hdfs
> Affects Versions: 3.4.0
> Reporter: Xing Lin
> Assignee: Xing Lin
> Priority: Minor
> Labels: pull-request-available
>
> When namenode HA is enabled and a standby NN is not responsible, we have
> observed it would take a long time to serve a request, even though we have a
> healthy observer or active NN.
> Basically, when a standby is down, the RPC client would (re)try to create
> socket connection to that standby for _ipc.client.connect.timeout_ _*
> ipc.client.connect.max.retries.on.timeouts_ before giving up. When we take a
> heap dump at a standby, the NN still accepts the socket connection but it
> won't send responses to these RPC requests and we would timeout after
> _ipc.client.rpc-timeout.ms._ This adds a significantly latency. For clusters
> at Linkedin, we set _ipc.client.rpc-timeout.ms_ to 120 seconds and thus a
> request takes more than 2 mins to complete when we take a heap dump at a
> standby. This has been causing user job failures.
> We could set _ipc.client.rpc-timeout.ms to_ a smaller value when sending
> getHAServiceState requests in ObserverReaderProxy (for user rpc requests, we
> still use the original value from the config). However, that would double the
> socket connection between clients and the NN (which is a deal-breaker).
> The proposal is to add a timeout on getHAServiceState() calls in
> ObserverReaderProxy and we will only wait for the timeout for an NN to
> respond its HA state. Once we pass that timeout, we will move on to probe the
> next NN.
>
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