[hibernate-issues] [Hibernate-JIRA] Issue Comment Edited: (HHH-5927) Performance risk: Suboptimal synchronization in org.hibernate.engine.query.QueryPlanCache.getHQLQueryPlan
[
https://hibernate.onjira.com/browse/HHH-5927?page=com.atlassian.jira.plug...
]
Strong Liu edited comment on HHH-5927 at 2/28/12 10:52 AM:
-----------------------------------------------------------
https://github.com/hibernate/hibernate-orm/pull/283
1. remove commons-collections dependency.
2. moved org.hibernate.internal.util.collections.ConcurrentReferenceHashMap from
envers module to core, and change it to doesn't allow null key / value.
3. Using ConcurrentReferenceHashMap this to replace old ReferenceMap (from
commons-collections) which used in StatefulPersistenceContext.
4. copied org.hibernate.internal.util.collections.BoundedConcurrentHashMap from
infinispan code base.
5. deprecate properties QUERY_PLAN_CACHE_MAX_STRONG_REFERENCES and
QUERY_PLAN_CACHE_MAX_SOFT_REFERENCES
6. add two new properties QUERY_PLAN_CACHE_PARAMETER_METADATA_MAX_SIZE and
QUERY_PLAN_CACHE_MAX_SIZE
7. remove LRUMap, SimpleMRUCache and SoftLimitMRUCache
was (Author: stliu):
https://github.com/hibernate/hibernate-orm/pull/283
1. remove commons-collections dependency.
2. moved org.hibernate.internal.util.collections.ConcurrentReferenceHashMap
3. Using ConcurrentReferenceHashMap this to replace old ReferenceMap (from c
4. copied org.hibernate.internal.util.collections.BoundedConcurrentHashMap f
5. deprecate properties QUERY_PLAN_CACHE_MAX_STRONG_REFERENCES and QUERY_PLA
6. add two new properties QUERY_PLAN_CACHE_PARAMETER_METADATA_MAX_SIZE and Q
7. remove LRUMap, SimpleMRUCache and SoftLimitMRUCache
Performance risk: Suboptimal synchronization in
org.hibernate.engine.query.QueryPlanCache.getHQLQueryPlan
---------------------------------------------------------------------------------------------------------
Key: HHH-5927
URL: https://hibernate.onjira.com/browse/HHH-5927
Project: Hibernate ORM
Issue Type: Improvement
Components: core
Reporter: Strong Liu
Assignee: Strong Liu
Attachments: hotspot.png
with Order Demo (real-life simulation attempt test app) I have noticed that there is
thread contention on createNamesQuery() which sounds suspicious.
After investigation it boils down to
org.hibernate.engine.query.QueryPlanCache.getHQLQueryPlan. It serves as a cache (internal,
not replacable) for queries using LRU algorithm (supplied from Apache utils).
Generally speaking, blocking threads in any sort of caches indicates a problem. From
about 2000 calls, 700 got blocked (which is also not nice for context switching).
I guess, one of the problems is that there is exclusive synchronization in get method:
public synchronized Object get(Object key) {...}
which could be replaced by a more granular read-write lock.
org/hibernate/engine/query/QueryPlanCache.java
org/hibernate/util/SoftLimitMRUCache.java
--
This message is automatically generated by JIRA.
For more information on JIRA, see: http://www.atlassian.com/software/jira