Marshall Schor created UIMA-3619:
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Summary: improve Cas FS to JCas cover instance map
Key: UIMA-3619
URL: https://issues.apache.org/jira/browse/UIMA-3619
Project: UIMA
Issue Type: Improvement
Components: Core Java Framework
Affects Versions: 2.5.0SDK
Reporter: Marshall Schor
Assignee: Marshall Schor
Priority: Minor
Fix For: 2.5.1SDK
In highly parallel environments running on multiple cores, profiling shows that
the JCas map has performance issues due to volatile and atomic operations that
are unneeded, but happen due to the use of the built-in Java Random function
(which uses volatile and atomic operations, internally). This map doesn't need
to support multi-threading operations - it is always used in a single-thread
manner. Other optimizations are possible, due to the limited way this table is
used. One of the common cases is an iterator fetching an existing FS from the
CAS, and needing to supply the corresponding JCas object (if it exists). This
operation first looks up in the Map using the address as the key, and if not
found, then makes the JCas object, and then adds it to the map - an operation
which repeats the same lookup in order to find the "empty slot" where it can
store the item. This extra lookup can be eliminated.
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