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This is the fourth part of the JVM Inside Out series. For your convenience you can find other parts in the table of contents in Part 1 — Getting object address Typical locking pattern in Java (and other languages, even outside them JVM ecosystem) looks like this: Simple enough, nothing should break here. However, there … Continue reading JVM Inside Out Part 4 — Locks and out of band exceptions
This is the third part of the JVM Inside Out series. For your convenience you can find other parts in the table of contents in Part 1 — Getting object address Erasure in Java seems pretty easy but sometimes it has unexpected consequences. One of them is erasure of whole class content, not only the … Continue reading JVM Inside Out Part 3 — Java raw type trickery
We know that to compare floating point values we should use epsilon and not just compare bits. We may run into similar issues when comparing BigDecimal in Java: What is the output? Of course it is false, otherwise I wouldn’t write this post. This is because BigDecimal includes scale: So we should use this: and … Continue reading Comparing numbers is hard
Recently I was debugging the following crash in Spark: Disabling Kryo solves the issue. To do that just set spark.serializer to org.apache.spark.serializer.JavaSerializer. Other workaround is to change Kryo’s reference management, as explained on Github:
Recently I was debugging a NullPointerException in Spark. The stacktrace was indicating this: After some digging I found out that the following query causes the problem: If I commented out the line with the comment the NPE was no longer there. Also, when I replaced either df2(“ref”) or df1(“ref”) with lit(“ref”) it was not crashing … Continue reading Spark and NullPointerException in UTF8String.contains