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https://issues.apache.org/jira/browse/JCR-3541?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
angela resolved JCR-3541.
-------------------------
Resolution: Incomplete
> Non-negligible probability of deadlock between
> AbstractCompiledPermissions.monitor and other actors
> ---------------------------------------------------------------------------------------------------
>
> Key: JCR-3541
> URL: https://issues.apache.org/jira/browse/JCR-3541
> Project: Jackrabbit Content Repository
> Issue Type: Bug
> Components: jackrabbit-core
> Affects Versions: 2.5.3
> Reporter: Lukas Eder
>
> There is a high probability of a deadlock between
> org.apache.jackrabbit.core.security.authorization.AbstractCompiledPermissions
> and other actors in jackrabbit-core's internals. The problem lies in the fact
> that AbstractCompiledPermissions.getResult() holds the monitor for quite a
> long time:
> synchronized (monitor) {
> result = cache.get(absPath);
> if (result == null) {
> if (absPath == null) {
> result = buildRepositoryResult();
> } else {
> result = buildResult(absPath); // Slow operation
> }
> cache.put(absPath, result);
> }
> }
> Implementations might run lots of code within buildResult(), which may
> eventually invoke the synchronized ItemManager methods, for instance, which
> themselves have a significant probability of passing through the
> AbstractCompiledPermissions again.
> I wonder whether synchronization should be limited to cache access, applying
> double-checked locking as such:
> Result result;
> synchronized (monitor) {
> result = cache.get(absPath);
> }
> if (result == null) {
> if (absPath == null) {
> result = buildRepositoryResult();
> } else {
> result = buildResult(absPath);
> }
> synchronized (monitor) {
> Result r = cache.get(absPath);
> if (r == null) {
> cache.put(absPath, result);
> }
> }
> }
> return result;
> Alternatively, to make things a bit more readable, the cache could be
> implemented using a ConcurrentHashMap.
> Note, the actual deadlock that I've got was probably due to abusing the
> Jackrabbit APIs in a custom AccessControlProvider
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