Maysam Yabandeh created KAFKA-4039:
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Summary: Exit Strategy: using exceptions instead of inline
invocation of exit/halt
Key: KAFKA-4039
URL: https://issues.apache.org/jira/browse/KAFKA-4039
Project: Kafka
Issue Type: Bug
Components: core
Affects Versions: 0.10.0.0
Reporter: Maysam Yabandeh
The current practice is to directly invoke halt/exit right after the line that
intends to terminate the execution. In the case of System.exit this could cause
deadlocks if the thread invoking System.exit is holding a lock that will be
requested by the shutdown hook threads that will be started by System.exit. An
example is reported by [~aozeritsky] in KAFKA-3924. This would also makes
testing more difficult as it would require mocking static methods of System and
Runtime classes, which is not natively supported in Java.
One alternative suggested
[here|https://issues.apache.org/jira/browse/KAFKA-3924?focusedCommentId=15420269&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-15420269]
would be to throw some dedicated exceptions that will eventually invoke
exit/halt:
{quote} it would be great to move away from executing `System.exit` inline in
favour of throwing an exception (two examples, but maybe we can find better
names: FatalExitException and FatalHaltException) that is caught by some
central code that then does the `System.exit` or `Runtime.getRuntime.halt`.
This helps in a couple of ways:
(1) Avoids issues with locks being held as in this issue
(2) It makes it possible to abstract the action, which is very useful in tests.
At the moment, we can't easily test for these conditions as they cause the
whole test harness to exit. Worse, these conditions are sometimes triggered in
the tests and it's unclear why.
(3) We can have more consistent logging around these actions and possibly
extended logging for tests
{quote}
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