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https://issues.apache.org/jira/browse/IGNITE-4477?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15976852#comment-15976852
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ASF GitHub Bot commented on IGNITE-4477:
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GitHub user dkarachentsev opened a pull request:
https://github.com/apache/ignite/pull/1844
IGNITE-4477 - Fix IgniteFuture.listen() and IgniteFuture.chain() semantics
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/gridgain/apache-ignite ignite-4477-1
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/ignite/pull/1844.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #1844
----
----
> Fix IgniteFuture.listen() and IgniteFuture.chain() semantics
> ------------------------------------------------------------
>
> Key: IGNITE-4477
> URL: https://issues.apache.org/jira/browse/IGNITE-4477
> Project: Ignite
> Issue Type: Task
> Components: general
> Affects Versions: 1.8
> Reporter: Vladimir Ozerov
> Assignee: Dmitry Karachentsev
> Labels: important
> Fix For: 2.1
>
>
> *Problem*
> We allow users to pass continuations to {{IgniteFuture}} which will be
> executed on future completion. This can be done through {{listen}} or
> {{chain}} methods.
> However, continuation semantics is broken intrinsically:
> 1) If future is already completed, user code executed in the same thread;
> 2) If future is not completed yet, it will be executed in completion thread.
> Neither of this options are valid because it easily leads to starvation. E.g.:
> {code}
> IgniteFuture fut = cache.getAsync(key2);
> fut.listen(fut0 -> {
> cache.put(key2, val2); // Possible deadlock, because invoked in sys pool;
> });
> {code}
> *Solution*
> 1) By default callbacks must be executed asynchronously in some common pool
> (public pool? new "callback pool"? FJP?)
> 2) It should be possible to specify where to execute a callback explicitly:
> {code}
> IgniteFuture.listen(IgniteClosure, ExecutorService);
> {code}
> 3) We may want to expose our public pool on API for convenience.
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