Details
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Bug
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Status: Resolved
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Normal
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Resolution: Invalid
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None
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None
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None
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Normal
Description
We're backporting CDC feature and bug fixes to 3.0. There is potential visibility issue with two variables CDCSizeTracker.sizeInProgress and DirectorySizeCalculator.size . They're declared as volatile however there are cases that when assigning new values to them, the new values depend on the current value. For example:
https://github.com/apache/cassandra/blob/e9da85723a8dd40872c4bca087a03b655bd2cacb/src/java/org/apache/cassandra/db/commitlog/CommitLogSegmentManagerCDC.java#L285
https://github.com/apache/cassandra/blob/e9da85723a8dd40872c4bca087a03b655bd2cacb/src/java/org/apache/cassandra/db/commitlog/CommitLogSegmentManagerCDC.java#L297
In rare cases we'll not be able to calculate CDC data size correctly. We should change these two variables back to AtomicLong, as the simplest fix. Java Concurrency In Practice section 3.1.3 explains well why we shouldn't use volatile in these two cases. I'll provide patch shortly.