https://bz.apache.org/bugzilla/show_bug.cgi?id=66178
Bug ID: 66178
Summary: Garbage from strings in
AbstractArchiveResourceSet.getResource
Product: Tomcat 8
Version: 8.5.x-trunk
Hardware: Macintosh
Status: NEW
Severity: normal
Priority: P2
Component: Catalina
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ----
Created attachment 38343
--> https://bz.apache.org/bugzilla/attachment.cgi?id=38343&action=edit
possible patch to reduce garbage
If you have a large-ish number of jars (something like 1200 in my case) then we
end up calling the getResource method of AbstractArchiveResourceSet for each
jar every time that we load a new resource. This code does a few substrings and
string concatenation that ends up generating a lot of garbage due to the fact
that it's called constantly.
This happens even if the resource is cached because of the code in
Cache.getResource()
If the entry is found in the cache we call it here
if (cacheEntry != null &&
!cacheEntry.validateResource(useClassLoaderResources)) {
Using JFR to capture some profiling data I was able to see that replacing the
string concatenation with a StringBuilder reduced the garbage by about 3x - 4x.
In the original, it created something like 20 mb when loading a page that
serves multiple resources and after the change, it only allocated about 7 mb.
Attached is a git patch showing a possible fix. I'd be happy to make a PR as
well.
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