If configured every read request schedules a Future task to send speculative reads on speculativeReadTimeout. When the read is completed successfully, this task must be canceled otherwise it leads to memory consumption and under heavy load the tasks get accumulated which forces lengthy GC cycles. These lengthy GC cycles may cause ZK lease expiry and all other sorts of problems eventually resulting in application errors.
This fix makes sure that the scheduled Futures are cancelled at the end of read task. Signed-off-by: Venkateswararao Jujjuri (JV) <[email protected]> (@ref Andrey@) Descriptions of the changes in this PR: ### Motivation (Explain: why you're making that change, what is the problem you're trying to solve) ### Changes (Describe: what changes you have made) Master Issue: #<master-issue-number> > --- > In order to uphold a high standard for quality for code contributions, Apache > BookKeeper runs various precommit > checks for pull requests. A pull request can only be merged when it passes > precommit checks. However running all > the precommit checks can take a long time, some trivial changes don't need to > run all the precommit checks. You > can check following list to skip the tests that don't need to run for your > pull request. Leave them unchecked if > you are not sure, committers will help you: > > - [ ] [skip bookkeeper-server bookie tests]: skip testing > `org.apache.bookkeeper.bookie` in bookkeeper-server module. > - [ ] [skip bookkeeper-server client tests]: skip testing > `org.apache.bookkeeper.client` in bookkeeper-server module. > - [ ] [skip bookkeeper-server replication tests]: skip testing > `org.apache.bookkeeper.replication` in bookkeeper-server module. > - [ ] [skip bookkeeper-server tls tests]: skip testing > `org.apache.bookkeeper.tls` in bookkeeper-server module. > - [ ] [skip bookkeeper-server remaining tests]: skip testing all other tests > in bookkeeper-server module. > - [ ] [skip integration tests]: skip docker based integration tests. if you > make java code changes, you shouldn't skip integration tests. > - [ ] [skip build java8]: skip build on java8. *ONLY* skip this when *ONLY* > changing files under documentation under `site`. > - [ ] [skip build java9]: skip build on java9. *ONLY* skip this when *ONLY* > changing files under documentation under `site`. > --- > --- > Be sure to do all of the following to help us incorporate your contribution > quickly and easily: > > If this PR is a BookKeeper Proposal (BP): > > - [ ] Make sure the PR title is formatted like: > `<BP-#>: Description of bookkeeper proposal` > `e.g. BP-1: 64 bits ledger is support` > - [ ] Attach the master issue link in the description of this PR. > - [ ] Attach the google doc link if the BP is written in Google Doc. > > Otherwise: > > - [ ] Make sure the PR title is formatted like: > `<Issue #>: Description of pull request` > `e.g. Issue 123: Description ...` > - [ ] Make sure tests pass via `mvn clean apache-rat:check install > spotbugs:check`. > - [ ] Replace `<Issue #>` in the title with the actual Issue number. > > --- [ Full content available at: https://github.com/apache/bookkeeper/pull/1665 ] This message was relayed via gitbox.apache.org for [email protected]
