support classloader metaspace stat#3188
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| event.getLong("classCount"), | ||
| event.getLong("chunkSize"), | ||
| event.getLong("blockSize"), | ||
| event.getLong("hiddenBlockSize")); |
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StatsRow.from unconditionally reads hiddenBlockSize, but jdk.ClassLoaderStatistics on older supported runtimes (e.g. JDK 11) does not expose that field, so event.getLong("hiddenBlockSize") throws at runtime and the whole classloader-metaspace command fails. Because the command is registered whenever JFR is present, this turns into a hard failure on those JDKs instead of degraded output; the parser should tolerate version differences (for example, fallback to unsafeAnonymousBlockSize or 0).
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Pull request overview
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This PR introduces a new classloader-metaspace command to report metaspace / class metadata memory per ClassLoader using JFR, along with terminal rendering, tests, and documentation.
Changes:
- Add
classloader-metaspacecommand implementation backed by JFRjdk.ClassLoaderStatistics - Add result model + view, register them in the command pack and view resolver
- Add English/Chinese docs and unit tests for parsing/sorting and table rendering
Reviewed changes
Copilot reviewed 11 out of 11 changed files in this pull request and generated 5 comments.
Show a summary per file
| File | Description |
|---|---|
| site/docs/en/doc/commands.md | Adds the new command to the English command index |
| site/docs/en/doc/classloader-metaspace.md | New English documentation page for classloader-metaspace |
| site/docs/doc/commands.md | Adds the new command to the Chinese command index |
| site/docs/doc/classloader-metaspace.md | New Chinese documentation page for classloader-metaspace |
| core/src/test/java/com/taobao/arthas/core/command/view/ClassLoaderMetaspaceViewTest.java | Tests rendering for default/verbose columns and narrow terminals |
| core/src/test/java/com/taobao/arthas/core/command/klass100/ClassLoaderMetaspaceCommandTest.java | Tests time parsing, display-name fallback, sorting/limit behavior |
| core/src/main/java/com/taobao/arthas/core/command/view/ResultViewResolver.java | Registers the new view for rendering |
| core/src/main/java/com/taobao/arthas/core/command/view/ClassLoaderMetaspaceView.java | Implements terminal table rendering for the command output |
| core/src/main/java/com/taobao/arthas/core/command/model/ClassLoaderMetaspaceModel.java | Adds a structured model for classloader-metaspace output |
| core/src/main/java/com/taobao/arthas/core/command/klass100/ClassLoaderMetaspaceCommand.java | Implements the new command using JFR recording + mapping event |
| core/src/main/java/com/taobao/arthas/core/command/BuiltinCommandPack.java | Registers the new command when JFR is available |
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| | Name | Specification | | ||
| | --------------------: | :-------------------------------------------------------------------------------------------------------------- | | ||
| | `[c:]` | ClassLoader hashcode, same format as `classloader -c` | | ||
| | `[classLoaderClass:]` | Filter by full ClassLoader class name | | ||
| | `[duration:]` | JFR sampling duration, `2500ms` by default; supports `ms`, `s`, `m`; a plain number means milliseconds | | ||
| | `[period:]` | `jdk.ClassLoaderStatistics` period, `500ms` by default; supports `ms`, `s`, `m` | | ||
| | `[limit:]` | Show only the first N rows after sorting by `chunkSize` descending | | ||
| | `[verbose:]` | Show full diagnostic columns, including `classLoaderData`, `hiddenBlockSize` and `type`; `-v` is also supported | |
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| | 参数名称 | 参数说明 | | ||
| | --------------------: | :--------------------------------------------------------------------------------- | | ||
| | `[c:]` | ClassLoader 的 hashcode，格式和 `classloader -c` 一致 | | ||
| | `[classLoaderClass:]` | 按 ClassLoader 完整类名过滤 | | ||
| | `[duration:]` | JFR 采样时长，默认 `2500ms`，支持 `ms`、`s`、`m`，裸数字按毫秒处理 | | ||
| | `[period:]` | `jdk.ClassLoaderStatistics` 采样周期，默认 `500ms`，支持 `ms`、`s`、`m` | | ||
| | `[limit:]` | 只输出按 `chunkSize` 降序排序后的前 N 行 | | ||
| | `[verbose:]` | 输出完整诊断列，包括 `classLoaderData`、`hiddenBlockSize` 和 `type`；也可使用 `-v` | |
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| long millis = Long.parseLong(text) * multiplier; | ||
| if (millis <= 0) { | ||
| throw new IllegalArgumentException(optionName + " must be greater than 0."); | ||
| } | ||
| return millis; | ||
| } catch (NumberFormatException e) { | ||
| throw new IllegalArgumentException(optionName + " is invalid: " + value); |
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| private static StatsRow from(RecordedEvent event) { | ||
| RecordedClassLoader loader = event.getValue("classLoader"); | ||
| long loaderId = loader == null ? 0 : loader.getId(); | ||
| String name = loader == null ? "BootstrapClassLoader" : loader.getName(); | ||
| return new StatsRow( | ||
| event.getStartTime(), | ||
| loaderId, | ||
| loader == null ? "null" : null, | ||
| name, | ||
| typeName(loader), | ||
| event.getLong("classLoaderData"), | ||
| event.getLong("classCount"), | ||
| event.getLong("chunkSize"), | ||
| event.getLong("blockSize"), | ||
| event.getLong("hiddenBlockSize")); | ||
| } |
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| private RecordingData readRecording(Path recording) throws IOException { | ||
| Map<Long, LoaderMapping> mappingByLoaderId = new HashMap<Long, LoaderMapping>(); | ||
| Map<Long, StatsRow> latestStatsByLoaderId = new HashMap<Long, StatsRow>(); | ||
| RecordingFile file = new RecordingFile(recording); | ||
| try { | ||
| while (file.hasMoreEvents()) { | ||
| RecordedEvent event = file.readEvent(); | ||
| String eventName = event.getEventType().getName(); | ||
| if (MAPPING_EVENT_NAME.equals(eventName)) { | ||
| RecordedClass anchorClass = event.getClass("anchorClass"); | ||
| RecordedClassLoader loader = anchorClass == null ? null : anchorClass.getClassLoader(); | ||
| if (loader != null) { | ||
| mappingByLoaderId.put(loader.getId(), LoaderMapping.from(event)); | ||
| } | ||
| } else if (STATS_EVENT_NAME.equals(eventName)) { | ||
| StatsRow row = StatsRow.from(event); | ||
| StatsRow previous = latestStatsByLoaderId.get(row.loaderId); | ||
| if (previous == null || row.startTime.isAfter(previous.startTime)) { | ||
| latestStatsByLoaderId.put(row.loaderId, row); | ||
| } | ||
| } | ||
| } | ||
| } finally { | ||
| file.close(); | ||
| } | ||
| return new RecordingData(mappingByLoaderId, latestStatsByLoaderId.values()); | ||
| } |
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