koo.taejin aa1447571b [CASSANDRA-21536] Profile pollution in AbstractType.writeValue makes serialization slow for all column types ... Description: AbstractType.writeValue() is one shared method. All column types use it. Inside writeValue(), it calls valueLengthIfFixed(). This is a virtual call. Many types override this method (Int32Type, LongType, UTF8Type, ...). In a real cluster, many column types pass through writeValue(). So the profile always sees lots types. Because of this, the JIT cannot inline the call. It stays as a vtable call. Also, the compiled body of writeValue() becomes big, so the JIT refuses to inline writeValue() itself ("already compiled into a big method"). We also see the same itable/vtable stubs in async-profiler output from a real cluster, running with default production options and a normal workload. How to solve: Add a final int field to AbstractType. Set it in the constructor. writeValue() reads this field instead of calling valueLengthIfFixed(). A field read needs no type profile. So profile pollution has no effect on it. The valueLengthIfFixed() method is not changed. Only the write path uses the field. Result: Production is always the polluted state, so this is the real-world comparison JMH, JDK 17 / arm64, 1 thread, 10 x 1s warmup and measurement: before after improvement readValue 49.99M ops/s 56.44M ops/s +12.90% writeValue 99.63M ops/s 114.46M ops/s +14.88% patch by Koo Taejin; reviewed by Dmitry Konstantinov, Francisco Guerrero for CASSANDRA-21536		2026-07-29 14:16:15 -05:00
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com/datastax/driver/core	Remove remaining driver dependencies from server code	2025-03-17 21:55:38 +01:00
org	[CASSANDRA-21536] Profile pollution in AbstractType.writeValue makes serialization slow for all column types	2026-07-29 14:16:15 -05:00