[PATCH] SFTP repositories become very slow after a while
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Key: IVY-973
URL: https://issues.apache.org/jira/browse/IVY-973
Project: Ivy
Issue Type: Improvement
Components: Core
Affects Versions: 2.0-RC2
Reporter: Johannes Rudolph
Attachments: faster-sftp.patch
If many versions of a module live in a folder of an SFTP repository each
resolve for dynamic versions becomes dreadfully slow because a roundtrip to the
server is made to the server for every version which lies on the server.
The call sequence goes like that:
org.apache.ivy.plugins.resolver.util.ResolverHelper.findAll calls
1. org.apache.ivy.plugins.resolver.util.ResolverHelper.listTokenValues which
calls
SFTPRepository.list with the directory of the module as parameter (1.
roundtrip)
2. for every found file matching the pattern
SFTPRepository.getResource(path).exists()
In turn SFTPResource tries to initialize itself and calls
SFTPRepository.resolveResource which does the second roundtrip to the server -
for every version of the file
Example: Having 20 versions of a module in a repository which is a roundtrip of
150ms away, leads to a lag of 20 * 150ms = 3s . Multiply that with any module
having a dynamic version.
The solution is to cache all the resources in SFTPRepository. You can use the
information retrieved when calling SFTPRepository.list to fill the cache in
advance.
The disadvantage is that you may have stale data. IMO this is mostly no problem
because every call to list updates the cache and files already available in the
repository won't hopefully change any metadata in the time between.
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