GeorgeJahad commented on code in PR #3653:
URL: https://github.com/apache/ozone/pull/3653#discussion_r954992484
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hadoop-ozone/ozone-manager/src/main/java/org/apache/hadoop/ozone/om/OzoneManager.java:
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@@ -710,6 +703,8 @@ private void instantiateServices(boolean withNewSnapshot)
throws IOException {
prefixManager = new PrefixManagerImpl(metadataManager, isRatisEnabled);
keyManager = new KeyManagerImpl(this, scmClient, configuration,
omStorage.getOmId());
Review Comment:
It is true that the writes are atomic. The problem is that Java makes no
guarantee that the writes will be visible to other threads, if they aren't
properly "synchronized", either with the volatile keyword or by using
synchronized blocks.
Here is a relatively short blog post explaining the issue:
https://www.logicbig.com/tutorials/core-java-tutorial/java-multi-threading/visibility-volatile.html
The best explanation I've found is in my favorite java book, "Java
Concurrency In Practice", chapter three, but it is a bit long:
https://leon-wtf.github.io/doc/java-concurrency-in-practice.pdf#%5B%7B%22num%22%3A63%2C%22gen%22%3A0%7D%2C%7B%22name%22%3A%22XYZ%22%7D%2C-6%2C466%2C1%5D
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