[jira] [Commented] (MESOS-6484) Memory leak in `Future::after()`

["Jie Yu (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/MESOS-6484?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15608946#comment-15608946 ] 

Jie Yu commented on MESOS-6484:
-------------------------------

This looks pretty scary...  [~arojas], do you plan to take a look at this?

> Memory leak in `Future<T>::after()`
> -----------------------------------
>
>                 Key: MESOS-6484
>                 URL: https://issues.apache.org/jira/browse/MESOS-6484
>             Project: Mesos
>          Issue Type: Bug
>          Components: libprocess
>    Affects Versions: 1.1.0
>            Reporter: Alexander Rojas
>              Labels: libprocess, mesosphere
>
> The problem arises when one tries to associate an {{after()}} call to copied futures. The following test case is enough to reproduce the issue:
> {code}
> class Policy
> {
> public:
>   virtual Try<Duration> timeout() = 0;
>   virtual Duration totalTimeout() = 0;
>   virtual ~Policy() {}
> };
> class MockPolicy : public Policy
> {
> public:
>   virtual ~MockPolicy() {}
>   MOCK_METHOD0(timeout, Try<Duration>());
>   MOCK_METHOD0(totalTimeout, Duration());
> };
> template <typename ResultType>
> process::Future<ResultType> retry(
>     const std::function<Future<ResultType>()>& action,
>     const std::shared_ptr<Policy>& policy)
> {
>   CHECK(policy != nullptr);
>   Try<Duration> timeout = policy->timeout();
>   if (timeout.isError()) {
>     return Future<ResultType>::failed(timeout.error());
>   }
>   return action()
>     .after(timeout.get(), [action, policy](const Future<ResultType>&) {
>       return retry<ResultType>(action, policy);
>     });
> }
> TEST(FutureTest, Retry)
> {
>   auto policy = std::make_shared<MockPolicy>();
>   EXPECT_CALL(*policy, timeout())
>       .WillRepeatedly(Return(Milliseconds(1)));
>   unsigned callCount = 0;
>   auto future = retry<Nothing>([&callCount]() -> Future<Nothing> {
>       ++callCount;
>       if (callCount < 4) {
>         return Future<Nothing>();
>       }
>       return Nothing();
>     },
>     policy);
>   AWAIT_READY(future);
>   EXPECT_EQ(1, policy.use_count());
> {code}
> In the test, one would expect that there is only one active reference to {{policy}}, therefore the expectation {{EXPECT_EQ(1, policy.use_count())}}. However, if after is triggered more than once, each extra call adds one undeleted reference to {{policy}}.



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