tandraschko opened a new pull request, #1030:
URL: https://github.com/apache/tomcat/pull/1030
## What
A set of internal, behavior-preserving optimizations that reduce web
application
deployment/startup time. There are **no changes to defaults, configuration,
public API, parsing output, or threading model** — outputs are identical;
only
redundant work and allocations are removed.
## Changes
**Annotation / JAR scanning (`ContextConfig`)**
- Index the `@HandlesTypes` types by name (class-file descriptor form for
annotations, binary name for classes) so matching a scanned class is an
O(1)
lookup instead of a linear scan of all handled types plus a per-annotation
string conversion.
- Record whether a fragment JAR contains `META-INF/resources/` during the
annotation scan (which already iterates every entry), so
`processResourceJARs`
no longer re-opens and re-scans each JAR.
- Check the cached default `web.xml` freshness with `File.lastModified()` for
`file:` URIs instead of opening a `URLConnection`.
- Use `Collections.singleton` for the per-fragment annotation merge.
**Mapper (`Mapper` / batch registration)**
- Register a context's servlet mappings into the copy-on-write wrapper
arrays in
a single merge per mapping category instead of reallocating the array once
per
mapping (previously O(n²)). Verified equivalent to the old sequential
`insertMap` behaviour (sorted order, existing-wins dedup, wildcard
`nesting`)
over 300k randomized cases.
**Web resources**
- `JarWarResourceSet`: build the `META-INF` bloom filter once when the
entries
are read rather than rebuilding it on every resource lookup.
- `AbstractSingleArchiveResourceSet`: pre-size the entry map from the JAR
entry
count.
- `StandardRoot`: hoist a loop invariant in `listResources`;
`Collections.addAll`
instead of `Arrays.asList` wrapper.
**Misc internal**
- `StandardJarScanner`: hoist loop-invariant `getJarFileURL()/toURI()` out
of the
manifest `Class-Path` loop; `Collections.addAll` for the class-path URLs.
- `Digester.updateAttributes`: resolve the class loader once per call.
- `FragmentJarScannerCallback`: single map lookup for duplicate detection.
- `StandardContext.mergeParameters`: iterate `entrySet()` directly.
- `LifecycleBase.fireLifecycleEvent`: skip allocating the event when there
are no
listeners.
- `AbstractProtocol.init`: compute the (built/quoted) name once.
- `MbeansDescriptorsIntrospectionSource`: `Set` membership test instead of a
linear array scan.
## Correctness
All changes preserve observable behaviour. The `Mapper` change was
fuzz-checked
against the original sequential implementation (identical arrays and
nesting).
`TestContextConfigAnnotation` is updated to build the new derived index
(mirroring
the normal `processClasses` flow). Please run at least `TestMapper*`,
`TestContextConfig*`, and the webresources tests.
## Performance
Measured on a build from source (JDK 25), median of 8 start/stop cycles, same
webapp set both sides. The gains scale with application size:
- Mapping-heavy app (~8000 classes, 20000 servlet mappings): server startup
~560 ms → ~483 ms (**~14%**).
- Small/typical apps: low single-digit %, near run-to-run noise.
Changelog entries are included.
Co-Authored-By: Claude Opus 4.8 <[email protected]>
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