liang xie created HDFS-4359:
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Summary: remove an unnecessary synchronized keyword in
BPOfferService.java
Key: HDFS-4359
URL: https://issues.apache.org/jira/browse/HDFS-4359
Project: Hadoop HDFS
Issue Type: Bug
Components: datanode
Affects Versions: 2.0.2-alpha, 3.0.0
Reporter: liang xie
Assignee: liang xie
we encountered a NN&DN hung issue, the DN hung was caused by no NN response for
heartbeat. Per DN thread dump, i think we can have a little improvement on this
detail code :
synchronized List<BPServiceActor> getBPServiceActors() {
return Lists.newArrayList(bpServices);
}
the bpServices is declared as :
private List<BPServiceActor> bpServices =
new CopyOnWriteArrayList<BPServiceActor>();
It's a thread-safe variant indead, so we can remove the above synchronized
keyword safely, IMHO.
Here is a simple statistic for thread dump:
xieliang@xieliang:/tmp$ grep 0x00000007b00289f0 dn.jstack |wc -l
252
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