Prevent classloader memory leak in ScratchBytes/ScratchChars#804
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garydgregory merged 1 commit intomasterfrom Oct 19, 2025
Merged
Prevent classloader memory leak in ScratchBytes/ScratchChars#804garydgregory merged 1 commit intomasterfrom
ScratchBytes/ScratchChars#804garydgregory merged 1 commit intomasterfrom
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Commit 0698bd9 introduced convenient `AutoCloseable` usage for `ScratchBytes` and `ScratchChars`. However, it also introduced a **classloader memory leak risk** in application server environments by storing custom wrapper instances directly in a `ThreadLocal`. This PR keeps the ergonomic `AutoCloseable` pattern while eliminating the classloader leak risk: * Store **only primitive buffers** (`byte[]` / `char[]`) in the `ThreadLocal`, not custom classes. * Introduce two types of `ScratchBytes` / `ScratchChars` instances: * **Global instance** (`buffer == null`) that fetches its buffer from the `ThreadLocal`. * **Reentrant instances** (`buffer != null`) for nested usage without interfering with shared buffers. **Note:** While this revision keeps the readability of using the `AutoCloseable` API, it also introduces a performance regression compared to the original #801 design: retrieving a buffer now requires two `ThreadLocal` lookups: once in `get()` and once in `array()`. The original design avoided this overhead intentionally. Since these classes are package-private and used in performance-sensitive paths, we should carefully weigh the trade-off between API convenience and runtime cost.
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Commit 0698bd9 introduced convenient
AutoCloseableusage forScratchBytesandScratchChars. However, it also introduced a classloader memory leak risk in application server environments by storing custom wrapper instances directly in aThreadLocal.This PR keeps the ergonomic
AutoCloseablepattern while eliminating the classloader leak risk:Store only primitive buffers (
byte[]/char[]) in theThreadLocal, not custom classes.Introduce two types of
ScratchBytes/ScratchCharsinstances:buffer == null) that fetches its buffer from theThreadLocal.buffer != null) for nested usage without interfering with shared buffers.Note: While this revision keeps the readability of using the
AutoCloseableAPI, it also introduces a performance regression compared to the original #801 design: retrieving a buffer now requires twoThreadLocallookups: once inget()and once inarray(). The original design avoided this overhead intentionally. Since these classes are package-private and used in performance-sensitive paths, we should carefully weigh the trade-off between API convenience and runtime cost.