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https://issues.apache.org/jira/browse/GROOVY-8097?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15900349#comment-15900349
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Jochen Theodorou commented on GROOVY-8097:
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Ok, so if I got you all right, there actually two issues here, that are
related. One is about internal API of Ivy not actually supporting multiple
threads. But actually you also have a problem with multiple JVMs trying to
download and write the same artefact into the disc cache at the same time.
Frankly, sounds "artifact-lock-nio" strategy could be part of the solution. It
is unclear to me why this decreased resolution times... and since this is using
file locks to me as if you get a kind of global "artifact-lock-nio" already.
Of course if you have 10 JVMs trying to download the same library at the same
time you get decreased resolution times, since it means they all have to wait
for this to be complete. But if you just start downloading the same artefact 10
times in parallel, you can easily corrupt the cache. This very much sounds to
me like the prize to pay in this case.
> Add an argument to set the resolution cache path in @Grab
> ---------------------------------------------------------
>
> Key: GROOVY-8097
> URL: https://issues.apache.org/jira/browse/GROOVY-8097
> Project: Groovy
> Issue Type: New Feature
> Components: Grape
> Affects Versions: 2.4.8
> Reporter: Ion Alberdi
> Priority: Minor
>
> Ivy does not support concurrent access to its resolution cache
> https://issues.apache.org/jira/browse/IVY-654
> Grape relies on Ivy. For this reason, Grape cannot support concurrent access
> to its resolution cache neither.
> When using the @Grab annotation in jenkins groovyCommand or
> systemGroovyCommand, the related code is vulnerable to race conditions. When
> the race condition appears in a systemGroovyCommand, we have no choice but to
> reboot jenkins as all consecutive calls to @Grab fail.
> Among the two solutions we tried:
> - Protect the calls to grab with a lock similar to ivy's "artifact-lock-nio"
> strategy. Works but slow.
> - Set Ivy's lock on the repository cache and setup Grab to use a different
> cache resolution cache for each concurrent jobs. The following code permits
> to fix a test we did to reproduce the race condition.
> {code}
> static IvySettings createIvySettings(String resolutionPath, boolean
> dumpSettings) {
> // Copy/Paste/Purged from GrapeIvy.groovy
> IvySettings settings = new IvySettings()
> settings.load(new File(GROOVY_HOME, "grapeConfig.xml"))
> // set up the cache dirs
> settings.defaultCache = new File(GRAPES_HOME)
> settings.setVariable("ivy.default.configuration.m2compatible", "true")
> settings.setDefaultResolutionCacheBasedir(resolutionPath)
> return settings
> }
> static GrapeIvy ivyWithCustomResolutionPath(String resolutionPath) {
> Class<?> grapeIvyClass = Class.forName("groovy.grape.GrapeIvy");
> Object instance = grapeIvyClass.newInstance()
> Field field = grapeIvyClass.getDeclaredField("ivyInstance");
> field.setAccessible(true);
> field.set(instance,
> Ivy.newInstance(createIvySettings(resolutionPath)));
> return ((GrapeIvy)instance)
> }
> {code}
> We'd like to propose to add an additional argument to Grab to setup Ivy's
> resolution cache directory.
> Note that this solution seems to have been adopted by these users too
> https://rbcommons.com/s/twitter/r/3436/
> Would you agree on such a feature ? We'd be glad to propose a PR.
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