Yu Lin created UIMA-4197:
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Summary: Using non-blocking "Future" instead of blocking
"Future.get" to improve performance?
Key: UIMA-4197
URL: https://issues.apache.org/jira/browse/UIMA-4197
Project: UIMA
Issue Type: Improvement
Components: DUCC
Reporter: Yu Lin
Priority: Minor
Hi, I'm doing research on asynchronous programming. I found at some places, the
code in uima-ducc ("trunk" branch) invokes "Future.get()" immediately after
starting a future task. Because "Future.get()" is a blocking call, the code
will block immediately.
For example, in "startAgents" method of "DuccAdmin" class (line 296), you
invoke "result.get()", where "result" is a Future, immediately after starting
future tasks, so the code blocks immediately. Such code has the same effect as
sequential code.
Why not use Guava ListenableFuture or Java8 CompletableFuture and avoid
"Future.get()"? These two new constructs provide callbacks to listen to the
Future's result:
http://docs.guava-libraries.googlecode.com/git/javadoc/com/google/common/util/concurrent/ListenableFuture.html
https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/CompletableFuture.html
For example, in "DuccAdmin" class, you may put the code after "result.get()"
(such as lines 301-307) into "CompletableFuture.thenRunAsync" method.
Then make "startAgents" method return this CompletableFuture, and in the
callers (such as "DuccAdmin.process()" or "DuccAdmin.main" method) you can put
more continuations into "CompletableFuture.thenRunAsync". And you can also
invoke "Future.get" somewhere in the callers (for example in
"DuccAdmin.process()" method), instead of immediately.
Do you think such kind of change is correct and can improve the code?
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