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https://issues.apache.org/jira/browse/HDFS-14074?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
guangyi lu updated HDFS-14074:
------------------------------
Release Note: (was: this.completedChecks = new ReferenceMap(1, 1);
or
this.completedChecks = new HashMap<>();)
Description:
In ThrottledAsyncChecker class，it members of the completedChecks is
WeakHashMap, its definition is as follows：
this.completedChecks = new WeakHashMap<>();
and one of its uses is as follows in schedule method:
if (completedChecks.containsKey(target)) {
// here may be happen garbage collection，and result may be null.
final LastCheckResult<V> result = completedChecks.get(target);
final long msSinceLastCheck = timer.monotonicNow() - result.completedAt;
。。。。
}
after "completedChecks.containsKey(target)"， may be happen garbage
collection， and result may be null.
the solution is：
this.completedChecks = new ReferenceMap(1, 1);
or
this.completedChecks = new HashMap<>();
was:
In ThrottledAsyncChecker class，it members of the completedChecks is
WeakHashMap, its definition is as follows：
this.completedChecks = new WeakHashMap<>();
and one of its uses is as follows in schedule method:
if (completedChecks.containsKey(target)) {
// here may be happen garbage collection，and result may be null.
final LastCheckResult<V> result = completedChecks.get(target);
final long msSinceLastCheck = timer.monotonicNow() -
result.completedAt;
}
after "completedChecks.containsKey(target)"， may be happen garbage
collection， and result may be null.
!image-2018-11-13-20-23-26-813.png!
> DataNode runs async disk checks maybe throws NullPointerException, and
> DataNode failed to register to NameSpace.
> ------------------------------------------------------------------------------------------------------------------
>
> Key: HDFS-14074
> URL: https://issues.apache.org/jira/browse/HDFS-14074
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: hdfs
> Affects Versions: 2.8.0, 3.0.0
> Environment: hadoop-2.7.3, hadoop-2.8.0
> Reporter: guangyi lu
> Priority: Major
> Original Estimate: 48h
> Remaining Estimate: 48h
>
> In ThrottledAsyncChecker class，it members of the completedChecks is
> WeakHashMap, its definition is as follows：
> this.completedChecks = new WeakHashMap<>();
> and one of its uses is as follows in schedule method:
> if (completedChecks.containsKey(target)) {
> // here may be happen garbage collection，and result may be null.
> final LastCheckResult<V> result = completedChecks.get(target);
>
> final long msSinceLastCheck = timer.monotonicNow() -
> result.completedAt;
> 。。。。
> }
> after "completedChecks.containsKey(target)"， may be happen garbage
> collection， and result may be null.
> the solution is：
> this.completedChecks = new ReferenceMap(1, 1);
> or
> this.completedChecks = new HashMap<>();
>
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