philwebb commented on issue #143: Apply deduplication to certain loaded and created Strings URL: https://github.com/apache/tomcat/pull/143#issuecomment-470145284 Sure. I discovered these by using the "Inspections" feature from [YourKit](https://www.yourkit.com/) on an [embedded Tomcat application](https://github.com/spring-projects/spring-boot/tree/87d696d6971c8bbd28be4fa885f9cf5719309c99/spring-boot-samples/spring-boot-sample-tomcat). Without the change YourKit reports 2192 duplicate Strings, with the change it's 1126 (so a saving of 1066). It's hard to get the exact memory saving but scanning the UI for the top hitters we have: | String | Duplicates | Waste | --- | --- | -- | "java.lang.String" | 2192 | 149112 | "ACTION" | 542 | 38952 | "boolean" | 191 | 10640 | "void" | 204 | 9744 | "Introspected parameter param0" | 80 | 8216 | "int" | 155 | 7392 | "[Ljava.lang.String;" | 42 | 3280 | So it looks like at least 227336 bytes can be saved. One other thing to consider is that I think these Strings are retained for the life of the application. They can't be GC'd because references remain until shutdown.
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